CA2179464A1 - Apparatus and method for sensing motionlessness in a vehicle - Google Patents
Apparatus and method for sensing motionlessness in a vehicleInfo
- Publication number
- CA2179464A1 CA2179464A1 CA002179464A CA2179464A CA2179464A1 CA 2179464 A1 CA2179464 A1 CA 2179464A1 CA 002179464 A CA002179464 A CA 002179464A CA 2179464 A CA2179464 A CA 2179464A CA 2179464 A1 CA2179464 A1 CA 2179464A1
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- Canada
- Prior art keywords
- vehicle
- operational
- sample
- motion state
- motion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
- G01C21/10—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
- G01C21/12—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning
- G01C21/16—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
- G01C21/18—Stabilised platforms, e.g. by gyroscope
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
- B61L25/00—Recording or indicating positions or identities of vehicles or vehicle trains or setting of track apparatus
- B61L25/02—Indicating or recording positions or identities of vehicles or vehicle trains
- B61L25/021—Measuring and recording of train speed
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P13/00—Indicating or recording presence, absence, or direction, of movement
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- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Mechanical Engineering (AREA)
- Gyroscopes (AREA)
- Navigation (AREA)
- Indicating Or Recording The Presence, Absence, Or Direction Of Movement (AREA)
Abstract
An apparatus and method for sensing motionlessness for sensing motionlessness in a land-based vehicle is provided. The apparatus can include an inertial measurement unit (IMU) mounted in a predetermined orientation on the vehicle and a programmable computer. The IMU can have an inertial sensor which generates a plurality of motion signals. More than one inertial sensor can be used and, in that case, each of the sensors can be mounted in a second predetermined orientation with respect to the others, such as an orthogonal orientation, thereby creating a selected spatial reference frame. The inertial sensor can be one or more accelerometers, or one or more gyroscopes, or an accelerometer-gyroscope combination. The computer receives the motion signals and determining a motion state of the vehicle therefrom. The computer provides the motion state to a target application which acts in accordance therewith. The method can include sensing a reference sample of motion signals during a reference period; extracting a reference characteristic signal from the reference sample; sensing an operational sample during an operational period; extracting an operational characteristic signal from the operational sample; determining the current motion state by comparing the operational characteristic signal to the reference characteristic signal; reporting the motion state to a target application in the vehicle, the application acting in accordance therewith.
Description
TITLE
APPARATUS AND METIIOD FOR
SENSING MOTIONLESSNESS IN A VEHICLE
B~CKGROUNn OF THF mYENTlON
1. Fi~ of ' I
The invention herein relates to vehicle sensors, particularly, to vehicle motion sensors, and more ~ iculally, to sensors for ~ " ~; ~ "~ when a vehicle is at rest, or mn~h~ e 2. ~ of the r Art It is often desirable to know when a venicle is at rest, i.e., be ellhst~ntisllly m~-~ionlr~ For example, a light-rail commuter vehicle can require accurate detection of the vehicle's IIIV~ `` 50 that the vehicle control system or the vehicle operator can open the vehicle doors to permit passengers to enter and depart. Typically, many land-based vehicle ~rFIirsltil~nc employ ~ ..,.. t- ~ to measure vehicle velocity. A
tachometer is an clc~ I angular speed transducer that can produce an output, e.g., a series of pulses, that is ~culc ~ ive of the vehicle's speed. However, at very low speeds, the tachometer output may not be detected or be properly int.orrr~tc~l leading to an erroneous irldication of the vehicle being m-~th-nl~
Inertial sensors, for example, gyroscopes and dCl,~ ulll~,t~ are often used in military and aerospace ~ such as rlavigation, guidance, and weapon fire control. More recently, inertial sensors have been used for guiding vehicle motion in P~ "C such as Ul~l~ an ~ ,.. , delivery robot through hospital 2~ 7~4~4 .
corridors, guiding an emergency vehicle deployed in an urban Cll`filUlllll~.~L, navigating an automated forklift in a warehouse, and so on.
Inertial sensors are useful in land-based ~ because, when a land-based vehicle travels between two points, a . ., ~ l f change in the vehicle's ~IrcPlPr~tinn vector can occur. This S~rcrlrrptinn vector can be ~i~....,.I,n~ irlto three directions, i.e., forward, lateral, and downward. These three directions are generally orthogonal and can form a spatial reference frame. The change in the forward direction is typically due to variations in the vehicle's desired speed which can result from factors such as land traction, joint stiction, and friction. The change in lateral ~rr~-lPr:~tinn can be due to turns, roughness of the land surface, roll in a vehicle, and the like.
FUI IIlClIIIUlC, changes in the downward ~... 1.... 1 ;1., . may result from vehicle vibration, in the vehicle path topology, vehicle pitch and roll, and the like. Thus, whenever the vehicle is not at rest, even if the vehicle speed is essentially constant, the df ~ -1 ;"' . vector usually reflects motions due to the ~ru-l -, .- - .1 ;- , .~ d effects, as sensed by an inertial sensor. An ac~f L IUl.l~,.Cl can measure the intensit,v and direction of an , .-produced force, from this, the magnitude and direction of the ~ ~ f 1 ,~
vector can be ~' ' A gyroscope can measure the intensity and direction of angular motion from which velocity vectors can be fif-tPrrnirrfi By integrating the outputs from an inertial sensor over time, one can determine the sensor's angular .i~ -- ....... and the sensor's linear velocity, I~,i,u. ~ ly.
Using time int~gr~tinn one can determine veloeity ;" r.., ...~ and, using an additional time int~rs~tir,n, can determine position ;.. r(.. ~;.. Practieally, however, it is diffieult ~ . 2~79~64 to exactly measure a specific vector, for example angular velocitv, without il~LIudu~ g or receiving some error. Over time, the errors can a- ' and the reported angular position and linear velocity are likely to diverge. Thus, velocity errors in a system will frequently be ~ ;dl,lc and the inertial n~lvi~diùll~l system may be unable to 1y .li~,, between the vehicle having a small velocity and the vehicle being at rest. Indeed, apparatus employing inertial sensors typically are employed to measure a vehicle's motion, and not m--tif~nl.-een.-ee due in part to such cumulative errors.
What is needed then is an apparatus and method for accurately sensing when a vehicle is m~tinnlFee In addition, other motion related ;. . r. " ., .~ .. . such as pitch, roll, yaw and speed also may be provided.
SUl~l~ARY OF Tl~li INVF~TION
The invention provides an apparatus and methûd for sensing .... ,l;..,.1 ~.,. -~ for sensing ,....~ in a land-based vehicle. The apparatus can include an inertial ll~ unit (IMU) mounted in a u.~ ~. . I l l;l lFCi orientation on the vehicle and a ~ a~ F computer. The IMU can have an inertial sensor which generates a plurality of motion signals. More than one inertial sensor can be used and, in that case, each of the sensors can be mounted in a second ~ ,1f ~ d orientation with respect to the others, thereby creating a selected spatial reference frame. In one ,I-û~l; I I- 11 the second ~ ;"~ I orientation is an orthogonal oriFntoti~n The inertial sensor can be one or more dCC~ I~ lUlll. t~l~, or one or more gyroscopes, or an a~c~ l, lUlll~ gyroscope c~.",l.;.. -:;....
2~79~4 The ~ A~ computer }eceives the motion signals and .11 a motion state of the vehicle therefrom. The motion state can include stopped and moving, where the stopped motion state is indicative of . . .~ .1;. .. ,1 ~. ,. ~ In one ..... I.o.l;-,,.. ,I,mntinnl~een~eeisrelativetoaL,I~,l. '~-.,.;-,~daxisofmovement,for example, the downward direction. The ~ computer provides the motion state to a target application which æts in accordance therewith. Where the land-based vehicle is a rail vehicle, the target application can be a rail vehicle control system.
A method for præticing the invention in a land-based vehicle having inertial sensors which provide motion signals can include sensing a reference sample c~l, d~ive of the motion signals during a reference period; extracting a reference ..1, --,,. t. . ;~ signal from the reference sample which can be lc~ llldlive of motinnl~ een~ ee sensing an operational sarnple Ic~ llaLive of the motion signals during am operational period; extracting an operational .1. --r. t- ,~1;. signal from the operational sample which can be Ic~l~ocll~alive of a current motion state; .1. t- . ,,.;1,;l,~ the current motion state from the operational I I~r r- 1. . ;~1;~ signal relative to the reference t. .;~l;. signal; reporting the motion state to a target application in the vehicle, the application acting in accordance therewith.
If the motion state is stopped, indicative of .. ~ then the inertial sensors can be IccalilJla~e~ and the process repeated with the sensing of a new operational sample. If the motion state is moving, additional operational samples can be taken and analyzed as described until a stopped motion state is detected. The reference ;-- signal can include a first standard deviation lc~ llLaliVe Of the referenCe 2 ~ 7q464 .
- s -sample, and the operational ~1, ,.. t` . ;`1 ;r signal can include a second standard deYiation a.,lltd~iV~ of the operational sample.
RRTF.F DE~CR~PTION OF TIIF DRAYVINGS
Figure I is a diagram of a land-based vehicle having an apparatus for sensing ~ according to the invention herein.
Figure 2 is a flow diagram of one . "l)oll; ........ 1 of the method for sensing mrltif~nlf eenf ee according to the invention herein.
Figure 3a is a time-based f~ 'Al plot for measured values of forward motion coupled with the projection of gravity on forward ~cf lf rs~tirm Figure 3b is a time-based .l~f 1- ~1 l.... plot for measured values of lateral motion coupled with the projection of gravity on lateral ~
Figure3cisatime-based~fl. .~;..,.plotformeasuredvaluesofa downward motion coupled with the projection of gravity on downward -... 1....1;, ...
Figure 4a is a time-based angular velocity plot for measured values of vehicle rolling motion coupled with the earth-rate projection on the roll gyroscope.
Figure 4b is a time-based angular velocity plot for measured values of vehicle pitch motion coupled with the earth-rate projection on the pitch gyroscope.
Figure 4c is a time-based angular velocity plot for measured values of downward motion coupled with the earth-rate projection on the yaw gyroscope.
DETAll.Fn DF!~RTPTION OF TIIF. PRF.FF.RRFI~ FMRODIMF,NTS
The invention herein provides an apparatus and method for detecting " ."1 ;.. ~ in a vehicle, ~Jf, l ~i~,UI~ a land-based vehicle, for example, a rail vehicle.
As used herein, ., ...~ does not describe the complete lack of movement in a vehicle. Instead"....~ can be relative to a ,u~ - t- ~ axis of movement, such as forward movement, and can be ~ ive of 5~lhct~nti~11y zero velocity in the direction of that lulr. 1. 1.. . ~I axis. The apparatus can include an inertial IlI~,~lalllCIII~
unit (IMU) having one or more inertial sensors that are mounted in a first UIC'~l~ t ~ d orientation on the vehicle. The apparatus can also include a ,UI~ computer for receiving motion signals from the IMU and cl. ~ .. ".. g the vehicle's motion state.
Where multiple inertial sensors are used, each sensor can be mounted in a second Ar~ I orientation with respect to the other sensors within the IMU. For exarnple, where three sensors are used, each senso} can be mounted orthogonally with respect to the other sensors so that a three-axis spatial reference frame can be f-~tohlichr~l An a~ ,l.,lulll~,t~.l can be used as am inertial sensor, although the apparatus instead can employ a gyroscope. Ful Illc:llllulr~ multiple ac.,~l~lulll~t~ gyroscopes, or cu, . ,1.; 1 ,,. l ,....
thereof, also may be used as inertial sensors. Each of the inertial sensors can generate multiple motion signals which can be received by the computer. The computer can, in turn, determine a motion state of the vehicle and provide the motion state to a target ~rr~i'`S'ti"n such as a rail vehicle control system, so that the target application carl respond to the motion state. Also, the motion state can be used by the computer for realigning the spatial reference frame and rcrolihrsltine the inertial sensors. In general, the motion states determined by the computer can include stopped amd moving. The motion state can include the vehicle's speed, and other parameters respective of movement relative to a particular sensor orientation such as pitch, roll, amd yaw.
2 1 7~4~
.
Figure I illustrates one ~,,,1~1l;.,,~ .,1 of apparatus I for sensing ~""~;(",lr ~ in a Yehicle 2 which can include an inertial ~ ,a~ unit (IMU) 3 and a ~/IU~ computer 4. IMU 3 can generate multiple motion signals and can be moumted in a first ~,~.1. ~. . ", ;., ~1 orientation on vehicle 2, which can be a land-based vehicle such as, for example, a rail vehicle, a bus, a tram, and the like. Computer 4 is connected to inertial Ill~,a ~CIII~,.. unit 3 and receives multiple motion signals 9 therefrom. Computer 4 can analyze motion signals 9 to determine a motion state of vehicle 2. The motion state can be one of stopped and moving, with the stopped motion state being indicative of nnf~t - ~ Computer 4 can provide the motion state 10 to a target arr1ir:~ti~-n which cam be vehicle control system 8. IMU 3 can have one or more inertial sensors 5, 6, 7. Each of inertial sensors 5, 6, 7 can be one or more acccl.l ullleters or one or more gyroscopes. Alternately, sensors 5, 6, 7 of IMU 3 can include at least one gyroscope and at least one ac. . l~.u.~ l. Although a single inertial sensor may be used in IMU 3, multiple inertial sensors also can be used. Where multiple inertial sensors S, 6, 7 are used, each sensor can be mounted in a second ~ " ,;,.. d orientation with respect to the other sensors.
As illustrated in Figure I, when IMU 3 employs three inertial sensors 5, 6, 7, the orientation can be an orthogonal ori~nf~.tinn, i.e., where each sensor is orthogonal with respect to the others. In such a three-sensor, orthogonal ~fmfi~llr~til~n, sensor 5 is oriented to the x-axis amd can be used to detect forward motion of vehicle 2. Likewise, sensor 6 is oriented to the y-axis and cam be used to sense lateral, or side-to-side, motion in vehicle 2. Sensor 7 is oriented to the z-axis and can detect downward movement in 21 7~464 vehicle 2. When a single inertial sensor, such as an acc~h,lv~ ,l, is employed in IMU
APPARATUS AND METIIOD FOR
SENSING MOTIONLESSNESS IN A VEHICLE
B~CKGROUNn OF THF mYENTlON
1. Fi~ of ' I
The invention herein relates to vehicle sensors, particularly, to vehicle motion sensors, and more ~ iculally, to sensors for ~ " ~; ~ "~ when a vehicle is at rest, or mn~h~ e 2. ~ of the r Art It is often desirable to know when a venicle is at rest, i.e., be ellhst~ntisllly m~-~ionlr~ For example, a light-rail commuter vehicle can require accurate detection of the vehicle's IIIV~ `` 50 that the vehicle control system or the vehicle operator can open the vehicle doors to permit passengers to enter and depart. Typically, many land-based vehicle ~rFIirsltil~nc employ ~ ..,.. t- ~ to measure vehicle velocity. A
tachometer is an clc~ I angular speed transducer that can produce an output, e.g., a series of pulses, that is ~culc ~ ive of the vehicle's speed. However, at very low speeds, the tachometer output may not be detected or be properly int.orrr~tc~l leading to an erroneous irldication of the vehicle being m-~th-nl~
Inertial sensors, for example, gyroscopes and dCl,~ ulll~,t~ are often used in military and aerospace ~ such as rlavigation, guidance, and weapon fire control. More recently, inertial sensors have been used for guiding vehicle motion in P~ "C such as Ul~l~ an ~ ,.. , delivery robot through hospital 2~ 7~4~4 .
corridors, guiding an emergency vehicle deployed in an urban Cll`filUlllll~.~L, navigating an automated forklift in a warehouse, and so on.
Inertial sensors are useful in land-based ~ because, when a land-based vehicle travels between two points, a . ., ~ l f change in the vehicle's ~IrcPlPr~tinn vector can occur. This S~rcrlrrptinn vector can be ~i~....,.I,n~ irlto three directions, i.e., forward, lateral, and downward. These three directions are generally orthogonal and can form a spatial reference frame. The change in the forward direction is typically due to variations in the vehicle's desired speed which can result from factors such as land traction, joint stiction, and friction. The change in lateral ~rr~-lPr:~tinn can be due to turns, roughness of the land surface, roll in a vehicle, and the like.
FUI IIlClIIIUlC, changes in the downward ~... 1.... 1 ;1., . may result from vehicle vibration, in the vehicle path topology, vehicle pitch and roll, and the like. Thus, whenever the vehicle is not at rest, even if the vehicle speed is essentially constant, the df ~ -1 ;"' . vector usually reflects motions due to the ~ru-l -, .- - .1 ;- , .~ d effects, as sensed by an inertial sensor. An ac~f L IUl.l~,.Cl can measure the intensit,v and direction of an , .-produced force, from this, the magnitude and direction of the ~ ~ f 1 ,~
vector can be ~' ' A gyroscope can measure the intensity and direction of angular motion from which velocity vectors can be fif-tPrrnirrfi By integrating the outputs from an inertial sensor over time, one can determine the sensor's angular .i~ -- ....... and the sensor's linear velocity, I~,i,u. ~ ly.
Using time int~gr~tinn one can determine veloeity ;" r.., ...~ and, using an additional time int~rs~tir,n, can determine position ;.. r(.. ~;.. Practieally, however, it is diffieult ~ . 2~79~64 to exactly measure a specific vector, for example angular velocitv, without il~LIudu~ g or receiving some error. Over time, the errors can a- ' and the reported angular position and linear velocity are likely to diverge. Thus, velocity errors in a system will frequently be ~ ;dl,lc and the inertial n~lvi~diùll~l system may be unable to 1y .li~,, between the vehicle having a small velocity and the vehicle being at rest. Indeed, apparatus employing inertial sensors typically are employed to measure a vehicle's motion, and not m--tif~nl.-een.-ee due in part to such cumulative errors.
What is needed then is an apparatus and method for accurately sensing when a vehicle is m~tinnlFee In addition, other motion related ;. . r. " ., .~ .. . such as pitch, roll, yaw and speed also may be provided.
SUl~l~ARY OF Tl~li INVF~TION
The invention provides an apparatus and methûd for sensing .... ,l;..,.1 ~.,. -~ for sensing ,....~ in a land-based vehicle. The apparatus can include an inertial ll~ unit (IMU) mounted in a u.~ ~. . I l l;l lFCi orientation on the vehicle and a ~ a~ F computer. The IMU can have an inertial sensor which generates a plurality of motion signals. More than one inertial sensor can be used and, in that case, each of the sensors can be mounted in a second ~ ,1f ~ d orientation with respect to the others, thereby creating a selected spatial reference frame. In one ,I-û~l; I I- 11 the second ~ ;"~ I orientation is an orthogonal oriFntoti~n The inertial sensor can be one or more dCC~ I~ lUlll. t~l~, or one or more gyroscopes, or an a~c~ l, lUlll~ gyroscope c~.",l.;.. -:;....
2~79~4 The ~ A~ computer }eceives the motion signals and .11 a motion state of the vehicle therefrom. The motion state can include stopped and moving, where the stopped motion state is indicative of . . .~ .1;. .. ,1 ~. ,. ~ In one ..... I.o.l;-,,.. ,I,mntinnl~een~eeisrelativetoaL,I~,l. '~-.,.;-,~daxisofmovement,for example, the downward direction. The ~ computer provides the motion state to a target application which æts in accordance therewith. Where the land-based vehicle is a rail vehicle, the target application can be a rail vehicle control system.
A method for præticing the invention in a land-based vehicle having inertial sensors which provide motion signals can include sensing a reference sample c~l, d~ive of the motion signals during a reference period; extracting a reference ..1, --,,. t. . ;~ signal from the reference sample which can be lc~ llldlive of motinnl~ een~ ee sensing an operational sarnple Ic~ llaLive of the motion signals during am operational period; extracting an operational .1. --r. t- ,~1;. signal from the operational sample which can be Ic~l~ocll~alive of a current motion state; .1. t- . ,,.;1,;l,~ the current motion state from the operational I I~r r- 1. . ;~1;~ signal relative to the reference t. .;~l;. signal; reporting the motion state to a target application in the vehicle, the application acting in accordance therewith.
If the motion state is stopped, indicative of .. ~ then the inertial sensors can be IccalilJla~e~ and the process repeated with the sensing of a new operational sample. If the motion state is moving, additional operational samples can be taken and analyzed as described until a stopped motion state is detected. The reference ;-- signal can include a first standard deviation lc~ llLaliVe Of the referenCe 2 ~ 7q464 .
- s -sample, and the operational ~1, ,.. t` . ;`1 ;r signal can include a second standard deYiation a.,lltd~iV~ of the operational sample.
RRTF.F DE~CR~PTION OF TIIF DRAYVINGS
Figure I is a diagram of a land-based vehicle having an apparatus for sensing ~ according to the invention herein.
Figure 2 is a flow diagram of one . "l)oll; ........ 1 of the method for sensing mrltif~nlf eenf ee according to the invention herein.
Figure 3a is a time-based f~ 'Al plot for measured values of forward motion coupled with the projection of gravity on forward ~cf lf rs~tirm Figure 3b is a time-based .l~f 1- ~1 l.... plot for measured values of lateral motion coupled with the projection of gravity on lateral ~
Figure3cisatime-based~fl. .~;..,.plotformeasuredvaluesofa downward motion coupled with the projection of gravity on downward -... 1....1;, ...
Figure 4a is a time-based angular velocity plot for measured values of vehicle rolling motion coupled with the earth-rate projection on the roll gyroscope.
Figure 4b is a time-based angular velocity plot for measured values of vehicle pitch motion coupled with the earth-rate projection on the pitch gyroscope.
Figure 4c is a time-based angular velocity plot for measured values of downward motion coupled with the earth-rate projection on the yaw gyroscope.
DETAll.Fn DF!~RTPTION OF TIIF. PRF.FF.RRFI~ FMRODIMF,NTS
The invention herein provides an apparatus and method for detecting " ."1 ;.. ~ in a vehicle, ~Jf, l ~i~,UI~ a land-based vehicle, for example, a rail vehicle.
As used herein, ., ...~ does not describe the complete lack of movement in a vehicle. Instead"....~ can be relative to a ,u~ - t- ~ axis of movement, such as forward movement, and can be ~ ive of 5~lhct~nti~11y zero velocity in the direction of that lulr. 1. 1.. . ~I axis. The apparatus can include an inertial IlI~,~lalllCIII~
unit (IMU) having one or more inertial sensors that are mounted in a first UIC'~l~ t ~ d orientation on the vehicle. The apparatus can also include a ,UI~ computer for receiving motion signals from the IMU and cl. ~ .. ".. g the vehicle's motion state.
Where multiple inertial sensors are used, each sensor can be mounted in a second Ar~ I orientation with respect to the other sensors within the IMU. For exarnple, where three sensors are used, each senso} can be mounted orthogonally with respect to the other sensors so that a three-axis spatial reference frame can be f-~tohlichr~l An a~ ,l.,lulll~,t~.l can be used as am inertial sensor, although the apparatus instead can employ a gyroscope. Ful Illc:llllulr~ multiple ac.,~l~lulll~t~ gyroscopes, or cu, . ,1.; 1 ,,. l ,....
thereof, also may be used as inertial sensors. Each of the inertial sensors can generate multiple motion signals which can be received by the computer. The computer can, in turn, determine a motion state of the vehicle and provide the motion state to a target ~rr~i'`S'ti"n such as a rail vehicle control system, so that the target application carl respond to the motion state. Also, the motion state can be used by the computer for realigning the spatial reference frame and rcrolihrsltine the inertial sensors. In general, the motion states determined by the computer can include stopped amd moving. The motion state can include the vehicle's speed, and other parameters respective of movement relative to a particular sensor orientation such as pitch, roll, amd yaw.
2 1 7~4~
.
Figure I illustrates one ~,,,1~1l;.,,~ .,1 of apparatus I for sensing ~""~;(",lr ~ in a Yehicle 2 which can include an inertial ~ ,a~ unit (IMU) 3 and a ~/IU~ computer 4. IMU 3 can generate multiple motion signals and can be moumted in a first ~,~.1. ~. . ", ;., ~1 orientation on vehicle 2, which can be a land-based vehicle such as, for example, a rail vehicle, a bus, a tram, and the like. Computer 4 is connected to inertial Ill~,a ~CIII~,.. unit 3 and receives multiple motion signals 9 therefrom. Computer 4 can analyze motion signals 9 to determine a motion state of vehicle 2. The motion state can be one of stopped and moving, with the stopped motion state being indicative of nnf~t - ~ Computer 4 can provide the motion state 10 to a target arr1ir:~ti~-n which cam be vehicle control system 8. IMU 3 can have one or more inertial sensors 5, 6, 7. Each of inertial sensors 5, 6, 7 can be one or more acccl.l ullleters or one or more gyroscopes. Alternately, sensors 5, 6, 7 of IMU 3 can include at least one gyroscope and at least one ac. . l~.u.~ l. Although a single inertial sensor may be used in IMU 3, multiple inertial sensors also can be used. Where multiple inertial sensors S, 6, 7 are used, each sensor can be mounted in a second ~ " ,;,.. d orientation with respect to the other sensors.
As illustrated in Figure I, when IMU 3 employs three inertial sensors 5, 6, 7, the orientation can be an orthogonal ori~nf~.tinn, i.e., where each sensor is orthogonal with respect to the others. In such a three-sensor, orthogonal ~fmfi~llr~til~n, sensor 5 is oriented to the x-axis amd can be used to detect forward motion of vehicle 2. Likewise, sensor 6 is oriented to the y-axis and cam be used to sense lateral, or side-to-side, motion in vehicle 2. Sensor 7 is oriented to the z-axis and can detect downward movement in 21 7~464 vehicle 2. When a single inertial sensor, such as an acc~h,lv~ ,l, is employed in IMU
3, it is preferred that the sensor be oriented as sensor 7, that is, relative to the downward-, or z-, axis of movement.
The invention herein also provides a method for sensing moti~ ' in a vehicle and may be used in ~ nj-m~til~n with the existing inertial sensors on a vehicle.
'rhe method cam ~ I for dynamic defects such as vehicle and engine, vibration, and random motions such as, for example, passenger movement in the vehicle, an unlevel vehicle platform, or vehicle pathway, and the like. The method includes sensing reference and operational samples of motion signals that are taken during reference and operational periods, ~ .,ly. The samples can include the vehicle's ~f 1~ l in each of the monitored directions. 'rhe reference sample can be taken while the vehicle is at rest, i.e., where the vehicle velocity in a ~JIrfirlr ~ ;1 axis of movement is essentially zero and the vehicle is c~h~ontjolly mf~til~n~ From the reference sarnple can be extracted multiple reference signals including a reference ~ - Ir~ signal; similarly, from the operational sample can be extracted multiple operational signals including an operational . 1 - ,.. 1. . ;~1;. signal. The method then can provide comparing the operational - l ,- ,- f~ ;. signal to the reference l -, ~ f ;~ signal to deterrnine a motion state. rhe motion state can be indicative of whether the vehicle is moving or stopped, and can include selected operational signals. 'rhe reference and operational signals can include directional d~ 1. .,.1;,...-, pitch, roll, yaw, position, and speed.
In general, the arvl.... .1 ;.."~ f.. ;~1 .. signals can be indicative of the vehicle motion state, and can include the variance of the respective reference and 2~794~4 .
g operational directional Af c f lPrAAtif n vectors. If the vehicle is determined to be mfltiAInlf~e~ that is, in the stopped motion state, selected ones of the operational signals can be used to align the inertial .~ .C...~ unit to a selected spatial reference frame and calibrate the inertial sensors. In addition, the stopped motion state i , . r..., . ~ ;.." can be used by the target ~rrlif fAtif n for example, the vehicle control system, to activate other devices on the vehicle, including permitting the vehicle doors to open. On the other hand, if the vehicle is determined to be in the moving motion state, another operational sample of the motion signals can be sensed, with multiple operational signals, including l .l IA. A- 1f ' ;~1 ;l signals, being extracted therefrom, as before. The operational ..l, ~ r . ;~ ir signal again can be compared to the reference signal to determine whether the vehicle is moving or stopped.
Figure 2 illustrates the method 100 by which the mf)tiA/nlPC~Anf~A of a vehicle can be sensed. At step 102, a 1~ .y ., .., IAl .1~ computer cam sense reference sample from the motion signals generated during a reference period by an inertial IIICf~ device, such as, for example, ,Ul~lslr 1111IAIl computer 4 and IMU 3 in Figure 1. The reference sample can include reference vector IP(0), wherein reference vector IP(0) is obtained while the vehicle is - - ' Generally, vector IP can be an A. c f l . ~ vector which itself is composed of directional Af f~ ~lf rAtifm vectors~ e.g~ A~
AY, and AZ, for each of the three directions sensed by the respective ~ f 1. . ", . ,. t . ~ In addition, a reference . I~A- A- t ;~ signal vector, which can include reference deviation vector cP~ is extracted from I~(0) at step 102. A ~ I relaxation factor a can beapplied to vector ~P to reduce the effects of noise in the l~ CIA.~ CllVilUIIIII~,II~.
2179~4 .
Reference deviation vector ~1' cam include the standard deviation of the motion signals, taken while the vehicle is at rest. For example, where ,u ~ {x,y,z}, ~X, EY, ~Z can be the standard deviations of directional ~ ;. ." vector AX, AY, AZ, ~ iv~ly, taken while the vehicle is at rest. Similarly, where the inertial sensors include gyroscopes, vector ~1l also can include the standard deviation of the respective directional angular velocities sensed thereby.
After ~ " at step 102, an operational sample can be collected from the motion signals of the aforem~onti~ ' inertial I~ au~LI~ ll device during an operational period, at step 104. To reduce the influence of highmagnitude transient b upon the operational sample, a moving-window sample vector can be employed for each of directional signal vectors IX(i), IY(i) and IZ(i), at step 106. A
moving-window sample vector can be provided by deleting the oldest data, i.e., the data with the lowest time index (i) value, and adding to the vector the most recently collected operational sample, so that the total number of samples, N, is m:lint~inr~ For example, as indicated in step 106, the sample vector is the x-direction at time i is:
lX(i) = [AX(i N), AX(i-N+l),...,A (i)]
where AX(i) is the ~c ~ .. . value for the x-direction obtained when time i = (i-N), (i-N+l), and (i), . ",~ ,ly. From the moving-window sample, vector l~l(i), can be extracted an operational .1. ~ signal vector, step 108. The operational ,.. t. . ;~ signal vector can include a standard deviation vector, c~, for each of directional vectors, Ix, IY, amd IZ, in l~'; mean estimates for each vector; as well as measures of pitch, roll, yaw, speed, and position.
21 ?9464 Under typical operational conditions, i.e., when the Yehicle is moving, the magnitude of standard deviation vector c~l' of sample vector I~l can be large when compared to the reference deviation vector ~". Although the standard deviation for a single directional vector, e.g., IX(i), may be used to detect ,. .~ the standard deviations of a plurality of directional vectors e.g., IY(i), IY(i), and IZ(i), can be used to further enhance the motion state fl~ ~` .. . I .;1.- ;` " at step 110. When the operational .. 1 ,,.. f.. ;~ signal is generally less than the reference . l ,~. ,.. f.. ;~1 ;. signal, at step 110, a stopped motion state can be detected. It is desirable to use a ..l ,_. ,.. Irl ;~1 ;~ signal based on a higher-order measure, such as a standard deviation, because the mean values of vectors l~'(i) can be influenced by differences in the vehicle (platform) orientation with respect to a selected spatial reference frame at different lll.,a~al.~ times.
If the operational l.~ signal vector, e.g., cs~ is less than a reference . l, ~ signal vector, e.g., a~ll, then the operational signal vectors can be frozen, step 112, as determined at the time the current stopped state was detected, i.e., at step 110. These operational signal vectors can be used to perform . c ~l ;~,, .., ....l of the vehicle to a selected spatial reference frame, for example, levelling of the platform, step 114. Static alignment can be performed using the mean values of directional vector Ill(i).
F~ LII.,.IIIUIC, while the vehicle remains at rest, the inertial sensors can be re~ alil 1, step 116, to r- ~C ' ' current operational conditions which can vary due to physical conditions, such as, t~ ,laLulc~ pressure, humidity, and the like.
The stopped motion state can be used by the target arrliratirn for example, vehicle control system 8 in Figure 1, to perform preselected vehicle functions ~1 7~4 ~
such as opening the vehicle doors, at step 118. Selected reference variables, can be updated, step 122, as needed, to properly reflect current operational conditions. Process 100 can continue by sensing a new operational sample at step 104. Likewise, if, at step 110, the vehicle motion state is determined to be moving, process 100 continues by sensing a new sample at step 104.
~AMPl F.
A land-based vehicle, i.e., a van, was used to .1- -- the invention herein An inertial ~ t unit, similar to IMU 3 in Figure 1, was mounted in the van, and included three orthogonally-mounted ac~ .ulll~ t~L . and three orthng~nAlly-mounted gyroscopes, as illustrated in Figure 1. The x-direction inertial sensors were oriented to measure forward motion, the y-direction sensors were oriented to measure lateral or side-to-side motion, and the z-direction sensors were oriented to measure downward motion. The inertial III~ signals, here analog signals, were received by a ~JIU,~ computer, similar to ~ 1-' computer 4 in Figure 1. In the computer, IMIJ motion signals were digitized, and stored in the computer for analysis.
The van was maintained at rest for an ;I~ period, was accelerated generally smoothly for a time, and then fl~c~ rAt~l until a full stop was reached. Sampling continued for several seconds after the van can to a rest.
Figures 3a-c are graphical IC~ lL~iull ~ of the ~ forces measured in the x, y, and z directions by the respective a. ~ .,l~ l~...l~ t. .~. Figures 4a-c are graphical lI-~UI~ UIIS of the angular velocities measured in the x, y, and z directions by the respective gyroscopes. As can be seen in Figures 3a-c and 4a-c, the van was at 2~ 79~
rest during a,u~lwdl~ ,ly the first five (S) seconds of Ill~,aaUI~ ' The van âlso can be seen in Figures 3a-c and 4a-c to be at rest at about 18.5 seconds after sampling began.
Because of the substantial variances between Ill. a~lllclll~ llt~ taken while the van was moving and when it was stopped, a higher-order measure, such as a stândard deviation, can be used to detect when the vehicle is at rest.
Higher-order measures can be especially useful in rugged CllVilUIIIII.,I.~, such as those of rail vehicles, where the mâgnitude of the vehicle motion signals can be large, ual~ lally when the vehicle is moving. In such cases, motion signal variances derived from a moving vehicle can be substantially greater than variances derived from the vehicle while at rest. Thus, m~tinnl~ecnPc~ can be detected rapidly and accurately using higher-order measures, such as standard deviations, even in ~llVilUI..l.~ .lt;, more hostile than those c~u~ cd by the van in the example.
While specific ~" .I ,~.l, " ,. . " ~ of the invention have been described in detail, it will be ~.u~ ciaLc~ by those skilled in the art that various mn~lifi~tinnc and to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular " ., ,g. . ". . ,: ~ disclosed are meant to be illustrâtive only and not limited to the scope of the invention which is to be given the full breadth of the following claims and any and all ~Tnho~1im~nt~ thereof.
The invention herein also provides a method for sensing moti~ ' in a vehicle and may be used in ~ nj-m~til~n with the existing inertial sensors on a vehicle.
'rhe method cam ~ I for dynamic defects such as vehicle and engine, vibration, and random motions such as, for example, passenger movement in the vehicle, an unlevel vehicle platform, or vehicle pathway, and the like. The method includes sensing reference and operational samples of motion signals that are taken during reference and operational periods, ~ .,ly. The samples can include the vehicle's ~f 1~ l in each of the monitored directions. 'rhe reference sample can be taken while the vehicle is at rest, i.e., where the vehicle velocity in a ~JIrfirlr ~ ;1 axis of movement is essentially zero and the vehicle is c~h~ontjolly mf~til~n~ From the reference sarnple can be extracted multiple reference signals including a reference ~ - Ir~ signal; similarly, from the operational sample can be extracted multiple operational signals including an operational . 1 - ,.. 1. . ;~1;. signal. The method then can provide comparing the operational - l ,- ,- f~ ;. signal to the reference l -, ~ f ;~ signal to deterrnine a motion state. rhe motion state can be indicative of whether the vehicle is moving or stopped, and can include selected operational signals. 'rhe reference and operational signals can include directional d~ 1. .,.1;,...-, pitch, roll, yaw, position, and speed.
In general, the arvl.... .1 ;.."~ f.. ;~1 .. signals can be indicative of the vehicle motion state, and can include the variance of the respective reference and 2~794~4 .
g operational directional Af c f lPrAAtif n vectors. If the vehicle is determined to be mfltiAInlf~e~ that is, in the stopped motion state, selected ones of the operational signals can be used to align the inertial .~ .C...~ unit to a selected spatial reference frame and calibrate the inertial sensors. In addition, the stopped motion state i , . r..., . ~ ;.." can be used by the target ~rrlif fAtif n for example, the vehicle control system, to activate other devices on the vehicle, including permitting the vehicle doors to open. On the other hand, if the vehicle is determined to be in the moving motion state, another operational sample of the motion signals can be sensed, with multiple operational signals, including l .l IA. A- 1f ' ;~1 ;l signals, being extracted therefrom, as before. The operational ..l, ~ r . ;~ ir signal again can be compared to the reference signal to determine whether the vehicle is moving or stopped.
Figure 2 illustrates the method 100 by which the mf)tiA/nlPC~Anf~A of a vehicle can be sensed. At step 102, a 1~ .y ., .., IAl .1~ computer cam sense reference sample from the motion signals generated during a reference period by an inertial IIICf~ device, such as, for example, ,Ul~lslr 1111IAIl computer 4 and IMU 3 in Figure 1. The reference sample can include reference vector IP(0), wherein reference vector IP(0) is obtained while the vehicle is - - ' Generally, vector IP can be an A. c f l . ~ vector which itself is composed of directional Af f~ ~lf rAtifm vectors~ e.g~ A~
AY, and AZ, for each of the three directions sensed by the respective ~ f 1. . ", . ,. t . ~ In addition, a reference . I~A- A- t ;~ signal vector, which can include reference deviation vector cP~ is extracted from I~(0) at step 102. A ~ I relaxation factor a can beapplied to vector ~P to reduce the effects of noise in the l~ CIA.~ CllVilUIIIII~,II~.
2179~4 .
Reference deviation vector ~1' cam include the standard deviation of the motion signals, taken while the vehicle is at rest. For example, where ,u ~ {x,y,z}, ~X, EY, ~Z can be the standard deviations of directional ~ ;. ." vector AX, AY, AZ, ~ iv~ly, taken while the vehicle is at rest. Similarly, where the inertial sensors include gyroscopes, vector ~1l also can include the standard deviation of the respective directional angular velocities sensed thereby.
After ~ " at step 102, an operational sample can be collected from the motion signals of the aforem~onti~ ' inertial I~ au~LI~ ll device during an operational period, at step 104. To reduce the influence of highmagnitude transient b upon the operational sample, a moving-window sample vector can be employed for each of directional signal vectors IX(i), IY(i) and IZ(i), at step 106. A
moving-window sample vector can be provided by deleting the oldest data, i.e., the data with the lowest time index (i) value, and adding to the vector the most recently collected operational sample, so that the total number of samples, N, is m:lint~inr~ For example, as indicated in step 106, the sample vector is the x-direction at time i is:
lX(i) = [AX(i N), AX(i-N+l),...,A (i)]
where AX(i) is the ~c ~ .. . value for the x-direction obtained when time i = (i-N), (i-N+l), and (i), . ",~ ,ly. From the moving-window sample, vector l~l(i), can be extracted an operational .1. ~ signal vector, step 108. The operational ,.. t. . ;~ signal vector can include a standard deviation vector, c~, for each of directional vectors, Ix, IY, amd IZ, in l~'; mean estimates for each vector; as well as measures of pitch, roll, yaw, speed, and position.
21 ?9464 Under typical operational conditions, i.e., when the Yehicle is moving, the magnitude of standard deviation vector c~l' of sample vector I~l can be large when compared to the reference deviation vector ~". Although the standard deviation for a single directional vector, e.g., IX(i), may be used to detect ,. .~ the standard deviations of a plurality of directional vectors e.g., IY(i), IY(i), and IZ(i), can be used to further enhance the motion state fl~ ~` .. . I .;1.- ;` " at step 110. When the operational .. 1 ,,.. f.. ;~ signal is generally less than the reference . l ,~. ,.. f.. ;~1 ;. signal, at step 110, a stopped motion state can be detected. It is desirable to use a ..l ,_. ,.. Irl ;~1 ;~ signal based on a higher-order measure, such as a standard deviation, because the mean values of vectors l~'(i) can be influenced by differences in the vehicle (platform) orientation with respect to a selected spatial reference frame at different lll.,a~al.~ times.
If the operational l.~ signal vector, e.g., cs~ is less than a reference . l, ~ signal vector, e.g., a~ll, then the operational signal vectors can be frozen, step 112, as determined at the time the current stopped state was detected, i.e., at step 110. These operational signal vectors can be used to perform . c ~l ;~,, .., ....l of the vehicle to a selected spatial reference frame, for example, levelling of the platform, step 114. Static alignment can be performed using the mean values of directional vector Ill(i).
F~ LII.,.IIIUIC, while the vehicle remains at rest, the inertial sensors can be re~ alil 1, step 116, to r- ~C ' ' current operational conditions which can vary due to physical conditions, such as, t~ ,laLulc~ pressure, humidity, and the like.
The stopped motion state can be used by the target arrliratirn for example, vehicle control system 8 in Figure 1, to perform preselected vehicle functions ~1 7~4 ~
such as opening the vehicle doors, at step 118. Selected reference variables, can be updated, step 122, as needed, to properly reflect current operational conditions. Process 100 can continue by sensing a new operational sample at step 104. Likewise, if, at step 110, the vehicle motion state is determined to be moving, process 100 continues by sensing a new sample at step 104.
~AMPl F.
A land-based vehicle, i.e., a van, was used to .1- -- the invention herein An inertial ~ t unit, similar to IMU 3 in Figure 1, was mounted in the van, and included three orthogonally-mounted ac~ .ulll~ t~L . and three orthng~nAlly-mounted gyroscopes, as illustrated in Figure 1. The x-direction inertial sensors were oriented to measure forward motion, the y-direction sensors were oriented to measure lateral or side-to-side motion, and the z-direction sensors were oriented to measure downward motion. The inertial III~ signals, here analog signals, were received by a ~JIU,~ computer, similar to ~ 1-' computer 4 in Figure 1. In the computer, IMIJ motion signals were digitized, and stored in the computer for analysis.
The van was maintained at rest for an ;I~ period, was accelerated generally smoothly for a time, and then fl~c~ rAt~l until a full stop was reached. Sampling continued for several seconds after the van can to a rest.
Figures 3a-c are graphical IC~ lL~iull ~ of the ~ forces measured in the x, y, and z directions by the respective a. ~ .,l~ l~...l~ t. .~. Figures 4a-c are graphical lI-~UI~ UIIS of the angular velocities measured in the x, y, and z directions by the respective gyroscopes. As can be seen in Figures 3a-c and 4a-c, the van was at 2~ 79~
rest during a,u~lwdl~ ,ly the first five (S) seconds of Ill~,aaUI~ ' The van âlso can be seen in Figures 3a-c and 4a-c to be at rest at about 18.5 seconds after sampling began.
Because of the substantial variances between Ill. a~lllclll~ llt~ taken while the van was moving and when it was stopped, a higher-order measure, such as a stândard deviation, can be used to detect when the vehicle is at rest.
Higher-order measures can be especially useful in rugged CllVilUIIIII.,I.~, such as those of rail vehicles, where the mâgnitude of the vehicle motion signals can be large, ual~ lally when the vehicle is moving. In such cases, motion signal variances derived from a moving vehicle can be substantially greater than variances derived from the vehicle while at rest. Thus, m~tinnl~ecnPc~ can be detected rapidly and accurately using higher-order measures, such as standard deviations, even in ~llVilUI..l.~ .lt;, more hostile than those c~u~ cd by the van in the example.
While specific ~" .I ,~.l, " ,. . " ~ of the invention have been described in detail, it will be ~.u~ ciaLc~ by those skilled in the art that various mn~lifi~tinnc and to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular " ., ,g. . ". . ,: ~ disclosed are meant to be illustrâtive only and not limited to the scope of the invention which is to be given the full breadth of the following claims and any and all ~Tnho~1im~nt~ thereof.
Claims (35)
1. An apparatus for sensing motionlessness in a vehicle comprising:
(a) an inertial measurement unit mounted in a predetermined orientation on said vehicle, said inertial measurement unit having an inertial sensor, said vehicle being a land-based vehicle, said inertial sensor generating a plurality of motion signals; and (b) a programmable computer operably connected to said inertial measurement unit for receiving said plurality of motion signals and for predetermined a motion state of said vehicle therefrom, said motion state including one of stopped and moving, said stopped motion state being indicative of said motionlessness, said programmable computer providing said motion state to a target application in said vehicle.
(a) an inertial measurement unit mounted in a predetermined orientation on said vehicle, said inertial measurement unit having an inertial sensor, said vehicle being a land-based vehicle, said inertial sensor generating a plurality of motion signals; and (b) a programmable computer operably connected to said inertial measurement unit for receiving said plurality of motion signals and for predetermined a motion state of said vehicle therefrom, said motion state including one of stopped and moving, said stopped motion state being indicative of said motionlessness, said programmable computer providing said motion state to a target application in said vehicle.
2. The apparatus of claim 1 wherein determining said motion state includes:
(a) sensing a first sample from said plurality of motion signals during a reference period;
(b) extracting a reference characteristic signal from said first sample;
(c) sensing a second sample from said plurality of motion signals during a operational period, said operational period occurring after said reference period;
(d) extracting an operational characteristic signal from said second sample; and (e) determining said motion state from said operational characteristic signal relative to said reference characteristic signal.
(a) sensing a first sample from said plurality of motion signals during a reference period;
(b) extracting a reference characteristic signal from said first sample;
(c) sensing a second sample from said plurality of motion signals during a operational period, said operational period occurring after said reference period;
(d) extracting an operational characteristic signal from said second sample; and (e) determining said motion state from said operational characteristic signal relative to said reference characteristic signal.
3. The apparatus of claim 1 wherein said inertial sensor is an accelerometer.
4. The apparatus of claim 1 wherein said inertial sensor is a gyroscope.
5. The apparatus of claim 1 wherein said land-based vehicle is a rail vehicle and said target application is a rail vehicle control system.
6. The apparatus of claim 1 wherein said motionlessness is relative to a predetermined axis of movement.
7. The apparatus of claim 6 wherein said predetermined axis of movement is the downward axis.
8. An apparatus for sensing motionlessness in a vehicle comprising:
(a) an inertial measurement unit having a plurality of inertial sensors mounted in a first predetermined orientation on said vehicle, each of said plurality of inertial sensors being mounted in a second predetermined orientation with respect to others of said plurality of inertial sensors in said inertial measurement unit, each of said plurality of inertial sensors generating a plurality of motion signals, said vehicle being a land-based vehicle, said second predetermined orientation providing a selected spatial reference frame thereby; and (b) a programmable computer operably connected to said inertial measurement unit for receiving said plurality of motion signals therefrom and for determining a motion state thereby including one of stopped and moving, said stopped motion state being indicative of said motionlessness, said programmable computer providing said motion state to a target application in said vehicle.
(a) an inertial measurement unit having a plurality of inertial sensors mounted in a first predetermined orientation on said vehicle, each of said plurality of inertial sensors being mounted in a second predetermined orientation with respect to others of said plurality of inertial sensors in said inertial measurement unit, each of said plurality of inertial sensors generating a plurality of motion signals, said vehicle being a land-based vehicle, said second predetermined orientation providing a selected spatial reference frame thereby; and (b) a programmable computer operably connected to said inertial measurement unit for receiving said plurality of motion signals therefrom and for determining a motion state thereby including one of stopped and moving, said stopped motion state being indicative of said motionlessness, said programmable computer providing said motion state to a target application in said vehicle.
9. The apparatus of claim 8 wherein determining said motion state includes:
(a) sensing a first sample from said plurality of motion signals during a reference period;
(b) extracting a plurality of reference signals from said first sample;
(c) sensing a second sample from said plurality of motion signals during an operational period, said operational period occurring after said reference period;
(d) extracting a plurality of operational signals from said second sample; and (e) determining said motion state from selected ones of said plurality of operational signals relative to selected ones of said plurality of reference signals.
(a) sensing a first sample from said plurality of motion signals during a reference period;
(b) extracting a plurality of reference signals from said first sample;
(c) sensing a second sample from said plurality of motion signals during an operational period, said operational period occurring after said reference period;
(d) extracting a plurality of operational signals from said second sample; and (e) determining said motion state from selected ones of said plurality of operational signals relative to selected ones of said plurality of reference signals.
10. The apparatus of claim 8 wherein said second predetermined orientation is an orthogonal orientation.
11. The apparatus of claim 8 wherein said plurality of inertial sensors is a plurality of accelerometers.
12. The apparatus of claim 8 wherein said plurality of inertial sensors is a plurality of gyroscopes.
13. The apparatus of claim 8 wherein said plurality of inertial sensors includes at least one accelerometer and at least one gyroscope.
14. The apparatus of claim 8 wherein said land-based vehicle is a rail vehicle and said target application is a rail vehicle control system.
15. The apparatus of claim 8 wherein said motionlessness is relative to a predetermined axis of movement.
16. The apparatus of claim 15 wherein said predetermined axis of movement is the downward axis.
17. The apparatus of claim 10 wherein determining said motion state includes:
(a) sensing a first sample from said plurality of motion signals during a reference period;
(b) extracting a plurality of reference signals from said first sample;
(c) sensing a second sample from said plurality of motion signals during an operational period, said operational period occurring after said reference period;
(d) extracting a plurality of operational signals from said second sample; and (e) determining said motion state from selected ones of said plurality of operational signals relative to selected ones of said plurality of reference signals.
(a) sensing a first sample from said plurality of motion signals during a reference period;
(b) extracting a plurality of reference signals from said first sample;
(c) sensing a second sample from said plurality of motion signals during an operational period, said operational period occurring after said reference period;
(d) extracting a plurality of operational signals from said second sample; and (e) determining said motion state from selected ones of said plurality of operational signals relative to selected ones of said plurality of reference signals.
18. The apparatus of claim 15 wherein said land-based vehicle is a rail vehicle and said target application is a rail vehicle control system.
19. The apparatus of claim 17 wherein said plurality of inertial sensors is a plurality of accelerometers.
20. The apparatus of claim 17 wherein said plurality of inertial sensors is a plurality of gyroscopes.
21. The apparatus of claim 17 wherein said plurality of inertial sensors includes at least one accelerometer and at least one gyroscope.
22. The apparatus of claim 8 wherein said moving motion state further comprises at least one of pitch, roll, and yaw.
23. A method for sensing motionlessness in a land-based vehicle having inertial sensors, each of said sensors providing motion signals, comprising the steps of:
(a) sensing a reference sample representative of said motion signals during a reference period;
(b) extracting a reference characteristic signal from said reference sample, said reference characteristic signal being representative of motionlessness;
(c) sensing an operational sample representative of said motion signals during an operational period;
(d) extracting an operational characteristic signal from said operational sample, said operational characteristic signal being representative of a current motion state;
(e) determining said current motion state from said operational characteristic signal relative to said reference characteristic signal, said motion state being one of stopped and moving, said stopped state being indicative of motionlessness;
(f) reporting said motion state to a target application in said vehicle, said target application acting in accordance therewith;
(g) if said motion state is moving, then repeating steps (c) through (h);
and (h) if said motion state is stopped, then recalibrating said inertial sensors, and repeating steps (c) through (h).
(a) sensing a reference sample representative of said motion signals during a reference period;
(b) extracting a reference characteristic signal from said reference sample, said reference characteristic signal being representative of motionlessness;
(c) sensing an operational sample representative of said motion signals during an operational period;
(d) extracting an operational characteristic signal from said operational sample, said operational characteristic signal being representative of a current motion state;
(e) determining said current motion state from said operational characteristic signal relative to said reference characteristic signal, said motion state being one of stopped and moving, said stopped state being indicative of motionlessness;
(f) reporting said motion state to a target application in said vehicle, said target application acting in accordance therewith;
(g) if said motion state is moving, then repeating steps (c) through (h);
and (h) if said motion state is stopped, then recalibrating said inertial sensors, and repeating steps (c) through (h).
24. The method of claim 23 wherein said reference characteristic signal includes a first standard deviation representative of said reference sample, and said operational characteristic signal includes a second standard deviation representative of said operational sample.
25. The method of claim 23 wherein each of said inertial sensors are mounted in a predetermined orientation respective of others of said inertial sensors, said orientation providing a selected spatial reference frame thereby.
26. The method of claim 25 wherein said predetermined orientation is an orthogonal orientation.
27. The method of claim 23 wherein said motionlessness is relative to a predetermined axis of movement.
28. The method of claim 27 wherein said predetermined axis of movement is the forward axis.
29. The method of claim 27 wherein said predetermined axis of movement is the downward axis.
30. The method of claim 23 wherein said operational characteristic signal includes at least one of vehicle pitch, and vehicle roll, and vehicle yaw, and vehicle velocity and vehicle position.
31. The method of claim 25 wherein step (h) of claim 23 further comprises at least one of realigning said selected spatial reference frame and selectively revising said reference characteristic signal.
32. The method of claim 23 wherein said land-based vehicle is a rail vehicle and said target application is a rail vehicle control system.
33. The method of claim 23 wherein said inertial sensors are accelerometers.
34. The method of claim 23 wherein said inertial sensors are gyroscopes.
35. The method of claim 23 wherein said inertial sensors include at least one accelerometer and at least one gyroscope.
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|---|---|---|---|
| US500,571 | 1990-03-28 | ||
| US08/500,571 US5736923A (en) | 1995-07-11 | 1995-07-11 | Apparatus and method for sensing motionlessness in a vehicle |
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|---|---|
| CA2179464A1 true CA2179464A1 (en) | 1997-01-12 |
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| CA002179464A Abandoned CA2179464A1 (en) | 1995-07-11 | 1996-06-19 | Apparatus and method for sensing motionlessness in a vehicle |
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| US (1) | US5736923A (en) |
| EP (1) | EP0753752A1 (en) |
| KR (1) | KR970005962A (en) |
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| CA (1) | CA2179464A1 (en) |
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1995
- 1995-07-11 US US08/500,571 patent/US5736923A/en not_active Expired - Lifetime
-
1996
- 1996-06-19 CA CA002179464A patent/CA2179464A1/en not_active Abandoned
- 1996-06-25 TW TW085107647A patent/TW301711B/zh active
- 1996-06-25 AU AU56189/96A patent/AU5618996A/en not_active Abandoned
- 1996-07-02 EP EP96110681A patent/EP0753752A1/en not_active Ceased
- 1996-07-10 MX MX9602715A patent/MX9602715A/en unknown
- 1996-07-11 KR KR1019960027913A patent/KR970005962A/en not_active Application Discontinuation
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| EP0753752A1 (en) | 1997-01-15 |
| AU5618996A (en) | 1997-01-23 |
| US5736923A (en) | 1998-04-07 |
| MX9602715A (en) | 1997-01-31 |
| KR970005962A (en) | 1997-02-19 |
| TW301711B (en) | 1997-04-01 |
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