Rear travel guidance system
First Claim
1. An improved, self-guided vehicle of the type which automatically follows an externally defined path, and which has a ground-engaging steerable wheel, sensor means mounted on the vehicle for generating a position error signal representative of the position of the vehicle with respect to the path in the forward direction and representative of the position of a virtual sense point and the path in the reverse direction, the sensor means comprising a pair of front sensors and a pair of rear sensors, each pair of sensors being mounted on the vehicle so as to normally straddle the path and each pair producing a sensor pair signal which is representative of the difference of the outputs of the particular pair of sensors, and steering actuator means attached to the ground engaging steering wheel and responsive to the position error signal to control the orientation of the steerable wheel to automatically steer the vehicle along the external path, wherein the improvement comprisesmeans for generating a difference signal which is representative of the weighted difference between the front sensor pair signal and the rear sensor pair signal wherein the difference has been weighted by a predetermined quantity;
- andmeans for combining the sensor pair signal from the forward sensors with the difference signal so that the position error signal corresponds to the front sensor pair signal when the vehicle is traveling in a forward direction along the path and corresponds to the sum of the front sensor pair signal and the difference signal when the vehicle is traveling in a reverse direction along the path.
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Accused Products
Abstract
An automatic guidance device for a self-powered cargo-moving vehicle operated by a vehicle-borne sensor which follows a buried, energized wire path and which includes sensor means mounted either between the fixed and steerable axles or in the front of the fixed axle of the vehicle for guiding the vehicle when it travels in a direction such that the fixed axle precedes the sensor by effectively generating a position error signal relative to the direction of travel, the position error signal provided by a pair of sensing coils whose outputs are combined to generate an error signal V=K(R-F)+F where R and F are the differences of the output of a pair of rear sensor, and a pair of forward sensors, respectively, and K is equal to the ratio of the distance between the forward pair of coils and the virtual sense point to the distance of the rear and forward pairs of coils.
31 Citations
4 Claims
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1. An improved, self-guided vehicle of the type which automatically follows an externally defined path, and which has a ground-engaging steerable wheel, sensor means mounted on the vehicle for generating a position error signal representative of the position of the vehicle with respect to the path in the forward direction and representative of the position of a virtual sense point and the path in the reverse direction, the sensor means comprising a pair of front sensors and a pair of rear sensors, each pair of sensors being mounted on the vehicle so as to normally straddle the path and each pair producing a sensor pair signal which is representative of the difference of the outputs of the particular pair of sensors, and steering actuator means attached to the ground engaging steering wheel and responsive to the position error signal to control the orientation of the steerable wheel to automatically steer the vehicle along the external path, wherein the improvement comprises
means for generating a difference signal which is representative of the weighted difference between the front sensor pair signal and the rear sensor pair signal wherein the difference has been weighted by a predetermined quantity; - and
means for combining the sensor pair signal from the forward sensors with the difference signal so that the position error signal corresponds to the front sensor pair signal when the vehicle is traveling in a forward direction along the path and corresponds to the sum of the front sensor pair signal and the difference signal when the vehicle is traveling in a reverse direction along the path. - View Dependent Claims (3)
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- 2. An improved, self-guided vehicle of the type which automatically follows an externally defined path and which has a ground-engaging steerable wheel, sensor means mounted on the vehicle for generating a position error signal representative of the position of the vehicle with respect to the path in the forward direction and representative of the position of a virtual sense point and the path in the reverse direction, the sensor means comprising a pair of front sensors and a pair of rear sensors, each of the pairs of sensors being mounted on the vehicle so as to normally straddle the path and each pair of sensors producing a sensor pair signal which is representative of the difference of the outputs of the particular pair of sensors, steering actuator means attached to the ground engaging steering wheel and responsive to the position error signal to control the orientation of the steerable wheel to automatically steer the vehicle along the external path, wherein the improvement comprises
sensor means for generating the position error signal relative to the virtual sense point to the rear of the vehicle when it travels in a backward direction along the path wherein the sensor means generates the position error signal (V) relative to the virtual sense point according to the formula - space="preserve" listing-type="equation">V=Q(R-F)+F
where R=sensor pair signal from the rear pair of sensors; F=sensor pair signal from the forward pair of sensors; and Q=constant=ratio of the distance between the front pair of sensors and the virtual sense point to the distance between the front and rear pairs of sensors. - View Dependent Claims (4)
Specification