Digital automatic speed control for railway vehicles

Claim 2

A digital system for automatically controlling the sense and extent of railway vehicle traction or braking, comprising first shift register means digitally synthesizing successive linear rates of reduction of velocity of the vehicle, from normal maximum speed limit, as a function of distance traveled, to establish a stopping profile operational mode for said vehicle, second shift register means for storing digital data representative of a maximum speed limit in the zone through which said vehicle is passing, third shift register means for storing digital data representative of a vehicle velocity consistent with the state of the stopping profile mode, comparator means responsive to said maximum speed limit representative data as stored in said second shift register means and to said data representative of a vehicle velocity as stored in said third shift register means for digital comparison thereof and for selection of the lower value of the two as the desired velocity of the vehicle, means responsive to digital data representative of wheel RPM of the vehicle for comparison against said desired velocity value and for selectably instituting vehicle traction and braking control of said vehicle to bring the actual vehicle velocity toward said desired vehicle velocity, and means for initiating periodic recomparison of the speed restriction data stored by said first shift register means with said third shift register means to determined whether a change has occurred in either restriction in time alternation with periodic reinstitution of said selective vehicle traction and braking control.

Claim 3

The invention according to claim 1, wherein the periods of said periodic recomparison is substantially equal to that of the response time of said vehicle to said selective traction and braking controls.

Claim 4

The invention according to claim 2, comprising means for generating a signal indicative of arrival of said vehicle at a point in said zone which is a predetermined distance from a next scheduled stopping point for monitoring the distance traveled by said vehicle from that point to said stopping point, means responsive to a measurement of said distance for modifying said vehicle velocity-representative data as a function of said successive linear rates of reduction of velocity and as a function of said distance.

Claim 5

The invention according to claim 3, further including means for monitoring the positioned accuracy of said vehicle at each scheduled stop, counter means for digitally accumulating data representative of the respective number of times said vehicle has stopped short of or beyond a preselected stopping point at each scheduled stop, and means responsive to accumulated stop position-representative data for changing said digital data representative of wheel RPM in such sense as to produce an apparent vehicle speed such as to cause said selective traction and braking control means to institute traction control tending to cause said vehicle to stop precisely at the preselected stopping point at future scheduled stops.

Claim 6

Apparatus for automatically controlling the movement of a car along a track, comprising first shift register means for storing a digital value representing an imposed upper limit on car speed for the portion of track along which the car is moving comparator means for periodically comparing the digital value recorded in said first shift register and representing said imposed upper speed limit with a digitally recorded value representative of the normal maximum speed limit in said portion of track, means responsive to said comparison means for selecting the lower of said digital values as a representation of the desired speed of the car, counter means for periodically storing a count proportional to the number of revolutions of a wheel of the car which occur in a pre-selected interval of time, to provide an indication of the actual speed of the car during that interval, means responsive to the storing by said counter means of a count indicating an actual car speed differing from said lower of said digital values selectively to control the braking effort or the propulsion effort in equal steps in a sense required to bring the actual speed of the car toward the desired speed, means further responsive to the count of said counter means for changing the digital value stored in said first shift register from normal maximum speed limit to successively lower values at successively greater linear rates, to gradually reduce the speed of the car at a succession of increasing rates of reduction, upon approach of the car to a scheduled stopping point, and means for alternately initiating said periodic comparison and said periodic count in successive time intervals.

Claim 7

Apparatus for automatically controlling the movement of a car along a track, comprising first shift register means for storing a digital value representing an imposed upper limit on car speed for the portion of track along which the car is moving comparator means for periodically comparing the digital value recorded in said first shift register and representing said imposed upper speed limit with a digitally recorded value representative of the normal maximum speed limit in said portion of track, means responsive to said comparison means for selecting the lower of said digital values as a representation of the desired speed of the car, counter means for periodically storing a count proportional to the number of revolutions of a wheel of the car which occur in a pre-selected interval of time, to provide an indication of the actual speed of the car during that interval, means responsive to the storing by said counter means of a count indicating an actual car speed differing from said lower of said digital values selectively to control the braking effort or the propulsion effort in equal steps in a sense required to bring the actual speed of the car toward the desired speed, means further responsive to the count of said counter means for changing the digital value stored in said first shift register from normal maximum speed limit to successively lower values at successively greater linear rates, to gradually reduce the speed of the car at a succession of increasing rates of reduction, upon approach of the car to a scheduled stopping point, and means for alternately initiating said periodic comparison and said periodic count in successive time intervals.

Claim 8

The invention according to claim 5, wherein each of said successive time intervals corresponds to the normal response time of said car to each of said equal steps of braking effort or propulsion effort.

Claim 9

The invention according to claim 5, further including means responsive to inaccuracy of car stopping position in the same direction at plural successive scheduled stopping points for changing the count to be stored by said counter means such as to provide an indication of apparent speed of the car differing from actual speed to an extent required to modify said braking or propulsion effort so as to reduce said inaccuracy at a future stop.

Claim 10

A speed profiling system for a vehicle, comprising first register means for storing a first digital format representative of a maximum permitted speed of said vehicle, second register means for storing a second digital format representative of a synthetic stopping profile for said vehicle, means for comparing said formats to select which of said digital formats represents the lower speed, and means responsive to only the selected format for controlling the speed profile of said vehicle.

Claim 11

A speed profiling system for a vehicle, comprising first register means for storing a first digital format representative of a maximum permitted speed of said vehicle, second register means for storing a second digital format representative of a synthetic stopping profile for said vehicle, means for comparing said formats to select which of said digital formats represents the lower speed, and means responsive to only the selected format for controlling the speed profile of said vehicle.

Claim 12

The system according to claim 8, wherein said last means includes means for measuring the actual speed of said vehicle and digitally storing a measure of said actual speed, and further includes means for comparing said measure against said selected format.

Claim 17

The method according to claim 11, including generating a digital count representing actual speed of said vehicle, making a comparison of said digital count with that selected one of said first and second digital data which represents the lower of the speeds, and selectively applying traction or braking to said train according to the comparison achieved in making said comparison.

Claim 20

The method according to claim 13, wherein said time increments are equal time increments.

Claim 23

The method according to claim 15, wherein said desired speeds are speeds established according to said velocity profile.

Claim 24

The method according to claim 15, wherein is included the further steps of modifying at least one of said formats in such sense and extent as to modify said velocity profiles as a function of the accuracy with which said vehicle attains said stops.

Claim 27

The method according to claim 18, wherein said speed profile is controlled in time spaced time increments only.

Claim 28

The method according to claim 19, wherein said speed profile includes plural discrete values of speed recorded in digital format.

Claim 29

The method according to claim 19, wherein sense inaccuracy is measured in terms of a digital format.

Claim 32

The method according to claim 22, wherein said predetermined speed profile is recorded in a digital format.

Claim 33

The method according to claim 22, wherein said signal is a digital format signal.

Claim 36

The method according to claim 25, wherein said predetermined speed profile is registered in a digital format.

Claim 37

The method according to claim 25, wherein said predetermined constant distance is measured in terms of a count of rotations of a wheel of said vehicle.

Claim 38

The method according to claim 25, wherein said signal representing accuracy is a digital count.

Claim 39

The method according to claim 25, wherein modifying said speed profile is accomplished by modifying said count of rotations of said wheel.

Claim 40

The method according to claim 25, wherein said predetermined speed profile is registered in a digital format, said predetermined constant distance is measured in terms of a count of the rotations of a wheel of said vehicle, and wherein said signal representing accuracy is a digital count.