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US 4,400,757 AGranted
Automatic speed control systems
AssigneeAssociated Engineering Limited
InventorKenneth B. Caldwell
Life of this patent
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AssigneeAssociated Engineering Limited
InventorKenneth B. Caldwell
Estimating the term…
An automatic speed control system is disclosed in which an error signal Ve, representing the speed error of the vehicle, is added to a ramp voltage, ramping between fixed values, to produce a control signal Vc. Two comparators compare Vc with upper and lower limits, respectively, so as to produce a pulse train on one of two lines depending on the sign of the error and having a mark-space ratio depending on the magnitude of the error. A circuit responds to the first pulse to occur in the pulse train from one of the two comparators when the vehicle is accelerating towards and overshooting a new desired speed and, via a switching circuit, lowers the upper limit applied to that comparator so as to lengthen the first pulses and help to reduce overshoot of the desired speed. When the vehicle ceases accelerating, the upper limit is switched back to the desired value, and is also switched back to its original setting when the speed falls by a preset amount.
An automatic speed control system for controlling the speed of a vehicle, comprising comparing means for comparing signals respectively representing the actual and desired speeds of the vehicle so as to produce an error signal having a sign and magnitude dependent on the sign and magnitude of the speed error (if any) between them, output means responsive to the error signal and capable of producing a first or a second control output according as to whether the actual vehicle speed is greater or less than the desired speed, speed correcting means operative to produce a speed correction in dependence on the magnitude of the control output received so as to tend to reduce the speed error to zero, and modifying means operative after the speed error has changed sign to modify at least one said control output whereby to provide a temporary change in the mean level of that control output.
An automatic speed control system for controlling a vehicle to run at a desired speed, comprising comparing means operative to compare signals respectively representing the actual and desired speeds of the vehicle and to produce an error signal dependent on the sign and magnitude of the speed error (if any), means for adding to the error signal a ramp signal ramping in a predetermined manner between fixed values, means for comparing the instantaneous amplitude of the resultant signal with upper and lower limits of respective predetermined values whereby to produce a first control output when and for so long as the instantaneous amplitude of the said resultant signal exceeds the upper limit and to produce a second control output when and for so long as the instantaneous amplitude of the said resultant signal falls below the lower limit, output means connected to receive each control output and operative to produce a speed correcting action whose magnitude is dependent on the mean level of that control output and whose sign depends on whether the control output is the first or the second control output, whereby to tend to reduce the speed error to zero, and means operative when the said resultant signal exceeds the upper limit for the first time following a change in sign of the speed error to lower the value of the upper limit by a predetermined amount so as to provide a temporary increase in the magnitude of the speed correcting action.
Dependencies are inferred from the claim text.