GB1578000A - Devices for guiding the track of trackless vehicles - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO DEVICES FOR GUIDING THE TRACK OF TRACKLESS VEHICLES (71) We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to arrangements for guiding the track of trackless vehicles.

One arrangement for guiding the track of a trackless vehicle is by means of a guide line running along the path of travel of the vehicle and by means of only one pick-up element which is used to detect the lateral distance between the pick-up element and the guide line. This pick-up element is disposed in the vicinity of the front of the vehicle, a memory being connected to the load side of the pick-up element and influencing the steering angle of the vehicle by means of a steering regulator in such a manner that the lateral distance between the pick-up element and the guide line is kept to a minimum.The guide line is preferably formed by a guide cable which is laid in or along the path of travel of the vehicle and has alternating current flowing through it and the pick-up element comprises a coil, preferably a pair of coils, in which signals can be induced by the magnetic field around the guide cable. In one such arrangement as disclosed in German Offenlegungsschrift 1 801 967, the alternating voltages induced in the coils of a front pair of coils are supplied individually to two inputs of a differential amplifier whose output voltage is fed to the steering regulator in a higher ratio than the output voltage of a second differential amplifier whose two inputs are individually supplied with the alternating voltages induced in the coils of a rear pair of coils.As a result of this relatively higher ratio signal mixing, the vehicle then moves back onto its guide cable according to an exponential function after each deviation from the guide cable. However, when the guide cable is laid in curves, it has been found that the deviations from the guide cable can only be kept small enough at low speeds of travel.

In order to be able to travel at relatively high speeds of travel with small deviations, an arrangement has been proposed wherein small deviations can be maintained with the aid of three coils and an appropriate signal processing device. For this purpose, however, it is necessary to detect the transverse distances from the guide cable at three points on the vehicle.

-According to the present invention there is provided an arrangement for guiding the track of a trackless vehicle by means of a guide line running along the path of travel of the vehicle and by means of at least one pick-up element which is used to detect the lateral distance between the longitudinal axis of the vehicle and the guide line and by means of a steering regulator which affects the steering angle of the vehicle in such a manner that the lateral distance between the pick-up element and the guide line is kept to a minimum, in which, several, at least two, lateral deviations which follow in succession with respect to time, are used to determine the radius of curvature of the guide line.

On the basis of these deviations, the vehicle data, the speed of travel and the steering angle, the radius of the curvature with which the section of guide line just covered has been laid can be calculated at any time with analog or preferably digital computing circuits. It is thereby possible to control parameters of the steering regulator in dependence upon the momentarily covered radius of curvature of the guide line.

Optimum regulator parameters may thus be prescribed and/or the regulator may adapt its parameters automatically to the state of travel.

Provision may be made for a desired steering angle to be deduced with the aid of the detected radius of curvature and to be introduced into the regulating signal, whilst, at the same time, the other regulating parameters are controlled in dependence upon the radius of curvature and the variables existing in the system. To save considerable circuitry costs and as a modification to this proposal, provision may be made for a desired steering angle to be deduced with the aid of the detected radius of curvature and to be introduced into the regulating signal, the other regulating parameters, however, being kept constant.

The invention will be further described by way of example with reference to the accompanying drawings which show schematically a trackless vehicle with an arrangement according to one embodiment of the invention and in which: Figure 1 is a schematic plan view looking down onto a vehicle, and Figure 2 is a section along the line II-II of Figure 1.

A vehicle 1 has two front wheels 3 and 4, which are pivotably articulated to its front axle 2, and two rear wheels 5 and 6 which are substantially fixedly mounted on a rear axle 7 of the vehicle which has a wheelbase e.

The path of travel of the vehicle 1 is fixed by a guide cable 9 which is laid close beneath a track or roadway 8 and has a audio-frequency alternating current flowing through. This alternating current produces a magnetic field which is concentric to the guide cable 9 and is indicated by the dashed lines 10 in Figure 2.

So that the magnetic field can be picked up and the respective position of the vehicle relative to the guide cable 9 can be detected a pair of coils 11. 12 is provided on the underneath side of the vehicle.

The alternating voltages induced in the coils 11 and 12 by the magnetic field 1() are supplied to a memory- and steering regulator unit which determines the radius of curve p from the successive distances y(t).

y(t-At), y(t-2At). etc.. at times spaced at At and then adjusts the steering angle 3 relative to the central longitudinal plane 13 so that the distance between the pair of coils and the guide cable is kept to a minimum.

If the radius of curvature of the track curve is known. then it is possible to set optimum regulating parameters for each state of travel or prescribe an optimum steering angle directly.

The technical advance achieved bv the invention lies in the fact that. by reducing the amount of apparatus and by using a new method for detecting the curvature of the desired track. it is possible to he able to travel any track curves a short lateral distance away from the guide cable. By using optimum parameters or by prescribing an optimum steering angle with the reduction in the number of components liable to become defective, the reliability of such a traffic system can be increased. If, however, faults occur, then they can be recognized early since the arrangement usually operates with very small deviations in the track.

Steering effort and wear can be minimized.

WHAT WE CLAIM IS: 1. An arrangement for guiding the track of a trackless vehicle by means of a guide line running along the path of travel of the vehicle and by means of at least one pick-up element which is used to detect the lateral distance between the longitudinal axis of the vehicle and the guide line, and by means of a steering regulator which affects the steering angle of the vehicle in such a manner that the lateral distance between the pick-up element and the guide line is kept to a minimum, in which several, at least two, lateral deviations of the longitudinal axis of the vehicle relative to the guide line which follow in succession with respect to time, are used to determine the radius of curvature of the guide line.

2. An arrangement as claimed in claim 1. in which the guide line is formed by a guide cable which is laid along the path of travel of the vehicle and has alternating current passing therethrough, and the pickup element comprises at least one coil in which signals can be induced by the magnetic field of the guide cable.

3. An arrangement as claimed in claim 1, in which the guide line is formed by a guide cable which is laid along the path of travel of the vehicle and has alternating current passing therethrough. and the pickup element is a pair of coils disposed symmetrically relative to a vertical longitudinal plane of the vehicle.

4. An arrangement as claimed in claim 1. 2 or 3. in which at least one of the parameters of the steering regulator is controllable in dependence upon the momentarily travelled radius of curve of the guide line.

5. An arrangement as claimed in claim 1. 2. 3 or 4, in which. with the aid of the radius of curvature. a desired steering angle is deduced and introduced into a regulating signal. and at the same time other regulating parameters are controlled in dependence upon the radius of the curve and variables which exist in the system.

6. An arrangement as claimed in any of claims 1 to 4. in which. with the aid of the radius of curvature. a-desired steering angle is deduced and introduced into a regulating signal, and the other regulating parameters are kept constant.

7. An arrangement for guiding the track

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. Provision may be made for a desired steering angle to be deduced with the aid of the detected radius of curvature and to be introduced into the regulating signal, whilst, at the same time, the other regulating parameters are controlled in dependence upon the radius of curvature and the variables existing in the system. To save considerable circuitry costs and as a modification to this proposal, provision may be made for a desired steering angle to be deduced with the aid of the detected radius of curvature and to be introduced into the regulating signal, the other regulating parameters, however, being kept constant. The invention will be further described by way of example with reference to the accompanying drawings which show schematically a trackless vehicle with an arrangement according to one embodiment of the invention and in which: Figure 1 is a schematic plan view looking down onto a vehicle, and Figure 2 is a section along the line II-II of Figure 1. A vehicle 1 has two front wheels 3 and 4, which are pivotably articulated to its front axle 2, and two rear wheels 5 and 6 which are substantially fixedly mounted on a rear axle 7 of the vehicle which has a wheelbase e. The path of travel of the vehicle 1 is fixed by a guide cable 9 which is laid close beneath a track or roadway 8 and has a audio-frequency alternating current flowing through. This alternating current produces a magnetic field which is concentric to the guide cable 9 and is indicated by the dashed lines 10 in Figure 2. So that the magnetic field can be picked up and the respective position of the vehicle relative to the guide cable 9 can be detected a pair of coils 11. 12 is provided on the underneath side of the vehicle. The alternating voltages induced in the coils 11 and 12 by the magnetic field 1() are supplied to a memory- and steering regulator unit which determines the radius of curve p from the successive distances y(t). y(t-At), y(t-2At). etc.. at times spaced at At and then adjusts the steering angle 3 relative to the central longitudinal plane 13 so that the distance between the pair of coils and the guide cable is kept to a minimum. If the radius of curvature of the track curve is known. then it is possible to set optimum regulating parameters for each state of travel or prescribe an optimum steering angle directly. The technical advance achieved bv the invention lies in the fact that. by reducing the amount of apparatus and by using a new method for detecting the curvature of the desired track. it is possible to he able to travel any track curves a short lateral distance away from the guide cable. By using optimum parameters or by prescribing an optimum steering angle with the reduction in the number of components liable to become defective, the reliability of such a traffic system can be increased. If, however, faults occur, then they can be recognized early since the arrangement usually operates with very small deviations in the track. Steering effort and wear can be minimized. WHAT WE CLAIM IS:

1. An arrangement for guiding the track of a trackless vehicle by means of a guide line running along the path of travel of the vehicle and by means of at least one pick-up element which is used to detect the lateral distance between the longitudinal axis of the vehicle and the guide line, and by means of a steering regulator which affects the steering angle of the vehicle in such a manner that the lateral distance between the pick-up element and the guide line is kept to a minimum, in which several, at least two, lateral deviations of the longitudinal axis of the vehicle relative to the guide line which follow in succession with respect to time, are used to determine the radius of curvature of the guide line.

2. An arrangement as claimed in claim 1. in which the guide line is formed by a guide cable which is laid along the path of travel of the vehicle and has alternating current passing therethrough, and the pickup element comprises at least one coil in which signals can be induced by the magnetic field of the guide cable.

3. An arrangement as claimed in claim 1, in which the guide line is formed by a guide cable which is laid along the path of travel of the vehicle and has alternating current passing therethrough. and the pickup element is a pair of coils disposed symmetrically relative to a vertical longitudinal plane of the vehicle.

4. An arrangement as claimed in claim 1. 2 or 3. in which at least one of the parameters of the steering regulator is controllable in dependence upon the momentarily travelled radius of curve of the guide line.

5. An arrangement as claimed in claim 1. 2. 3 or 4, in which. with the aid of the radius of curvature. a desired steering angle is deduced and introduced into a regulating signal. and at the same time other regulating parameters are controlled in dependence upon the radius of the curve and variables which exist in the system.

6. An arrangement as claimed in any of claims 1 to 4. in which. with the aid of the radius of curvature. a-desired steering angle is deduced and introduced into a regulating signal, and the other regulating parameters are kept constant.

7. An arrangement for guiding the track

of a trackless vehicle, constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawings.