JP2707245B2 - Steering system for automatically traveling vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering device for an automatically traveling vehicle, and more particularly to a steering device for an automatically traveling vehicle that can switch between automatic steering and manual steering. 2. Description of the Related Art In recent years, various technologies have been developed for unmannedly traveling vehicles that automatically travel, such as automobiles and transport vehicles. For example,
A number of guided self-driving vehicles that travel according to a required course have already been put to practical use. There has also been proposed a non-guidance type unmanned automatically traveling vehicle that can autonomously travel while recognizing its own position by giving course information to a control system of the automatically traveling vehicle. Guided or non-guided autonomous vehicles are developed on the premise that humans do not ride as pilots, so many vehicles do not have steering handles, but they can be steered with the steering wheel. Some are marked. Problems to be Solved by the Invention Conventional guided or non-guided autonomously traveling vehicles include:
Some vehicles are not provided with a steering wheel, and such vehicles have a disadvantage in that when the guidance course is removed, the operation of returning to the correct course is troublesome. Autonomous vehicles equipped with conventional autopilots include:
Some are designed to be steered by the steering wheel,
If the handle shaft turned by the handle and the autopilot are not connected so as to be switchable, there is a drawback that the handle rotates together with the autopilot. For example, it is conceivable that an electric cart or the like used in a golf course can be automatically operated, and it is very convenient if the automatic operation and the manual operation can be switched so that a human can ride even during the automatic operation. In this case, if turning drive means such as a motor is connected to the steering shaft and the handle shaft is connected to the steering shaft, a phenomenon in which the steering wheel rotates during automatic steering cannot be avoided. For this reason, when the occupant is gripped by the steering wheel during automatic driving, the arm must be moved together with the movement of the steering wheel, and there is a drawback that the riding comfort is deteriorated. In addition, some vehicles that are automatically driven and equipped with a conventional autopilot device have an autopilot unit that is switchably connected to a steering shaft. It is not possible to eliminate the disadvantage that the handle shaft rotates. Further, in some vehicles that are automatically driven and equipped with a conventional automatic steering device, the steering shaft is turned using a servomotor or the like.However, when a servomotor is used, the number of revolutions is increased in order to apply feedback. It is necessary to provide an encoder and the like for detecting, and the configuration of the steering device becomes complicated, which is effective for a large vehicle that travels automatically.However, it is effective for a small vehicle that travels automatically such as a cart used at a golf course. There is a disadvantage that it cannot be adopted. The problem to be solved by the present invention is to provide a steering device for an automatically traveling vehicle that does not have the above-mentioned disadvantages of the prior art. In other words, it is possible to switch between automatic steering and manual steering, and to perform automatic steering. It is an object of the present invention to provide a steering apparatus for an automatically traveling vehicle that has a simple structure of a turning drive means for the vehicle and can realize a smooth steering operation without causing a slip between a traveling surface and wheels. Means for Solving the Problems The present invention provides means for solving the above problems,
The following configuration is adopted. The configuration of the present invention includes a plurality of wheels including at least one wheel steered by a steering shaft, a rotation driving unit for rotating any of the plurality of wheels, a turning driving unit for turning the steering shaft, and a turning operation. In an automatically traveling vehicle having a driving device and a control device for controlling a rotation driving device, a handle shaft is configured to be able to be turned by the handle, and the turning drive device is configured to reduce the rotation of the step motor by reducing the rotation of the step motor. One of the turning drive means and the handle shaft is connected to the steering shaft via the switching means, and the steering shaft is turned by the turning drive means or the handle shaft connected to the steering shaft. The at least one rider is provided at a position where the steering wheel can be operated, and at the time of stopping the steering axis during automatic driving,
When the steering is performed by the turning drive means toward the clockwise or counterclockwise target steering angle, the rotation of the step motor is initially gradually increased in angular speed, made constant in the middle, and gradually ended in angular speed. To make it reach the target steering angle, and during the clockwise or counterclockwise turning of the steering axis during automatic steering, aim at the counterclockwise or clockwise target steering angle opposite to the turning direction. When the steering is performed by the turning drive means, the rotation of the step motor is gradually decreased in angular velocity, and then gradually increased in the opposite direction, to a constant speed in the middle, and gradually decreased in the end. And a control device for causing the vehicle to reach the target steering angle. According to the steering apparatus of the present invention, one of the turning drive means and the handle shaft is connected to the steering shaft via the switching means, and the turning drive means or the handle connected to the steering shaft is provided. Since the steering shaft is turned by the shaft, and at least one rider is provided at a position where the steering wheel can be operated, it is possible to perform automatic steering by the swing driving means or manual steering by the steering wheel. ,
At the time of automatic steering by the turning drive means, since the connection between the steering shaft and the steering shaft is disconnected, the steering wheel does not rotate with the steering shaft. Further, in the steering apparatus for an automatically traveling vehicle according to the present invention, since the turning drive means is constituted by the step motor and the deceleration means for decelerating the rotation of the step motor, automatic steering can be performed by a small motor, and When the steering shaft is stopped at the time of automatic steering, when the steering is performed by the turning drive means toward the clockwise or counterclockwise target steering angle, the rotation of the step motor is initially gradually increased in angular velocity,
At the middle, the speed is made constant, and at the end, the angular speed is gradually reduced to reach the target steering angle.Also, during the clockwise or counterclockwise turning of the steering axis during automatic steering, the counterclockwise When the steering is performed by the turning drive means toward the clockwise or clockwise target steering angle, the rotation of the step motor is gradually decreased in angular speed, and then gradually increased in the opposite direction. At constant speed, the end can be controlled to gradually reduce the angular speed and reach the target steering angle, so that smooth steering operation that does not cause slip between the running surface and the wheels Can be easily realized. FIG. 1 shows an embodiment in which the invention of this application is applied to an automatically traveling vehicle that can be switched between automatic driving and manual driving. In this embodiment, a description will be given of a three-wheel type unmanned vehicle which has two front wheels which are not steered and one unsteered rear wheel which is steered by a steering shaft. The ring may be of two four-wheel type. The body frame 1 is formed of, for example, a pipe frame made of a steel pipe, and an upper frame 1a extending upward in an inverted L-shape is coupled to a rear end thereof. A head pipe 3 is provided at the front end of the body frame 1,
A steering shaft 4 is rotatably supported by the head pipe 3, and the front wheel 2 is mounted below the steering shaft 4. A pair of axles connected to the rear of the body frame 1 via a differential mechanism 6 are provided.
The rear wheels 5a and 5b are mounted on the vehicle, and the rear wheels 5a and 5b are rotated by a traveling drive motor 7 mounted on a rear portion of the vehicle body frame 1. The rotation of the motor 7 is transmitted to the differential mechanism 6 after being decelerated by a transmission including a tooth wheel, a chain 8a, and a chain 8b. At the rear end of the body frame 1, a step 9 for a person to board is fixed. A holder 10 is provided at a front end of the vehicle body frame 1, a steering shaft 4 is rotatably mounted on the holder 10, and a turning drive unit for turning the steering shaft 4 is provided above the steering shaft 4. The turning drive means includes a steering motor 11 and a speed reducer 12, and an output shaft of the speed reducer 12 is connected to an upper end of the steering shaft 4. A handle shaft 14 is connected to the housing of the speed reducer 12 via a link 13. By operating the switching means, one of the rotation of the steering motor 11 and the rotation of the handle shaft 14 is steered. The power is transmitted to the shaft 4. For example, when the rotation of the steering motor 11 is transmitted to the steering shaft 4, the speed is reduced to 1/30 by the speed reducer 12, and when the rotation of the handle shaft 14 is transmitted to the steering shaft 4, the ratio is 1: 1. It is intended to be communicated as it is. The handle shaft 14 is provided on a support portion provided on the body frame 1.
15a and a supporting portion 15b fixed to the upper frame 1a are rotatably supported, and a handle 14a is fixed to the upper end thereof. In this embodiment, a pair of rotary encoders 20a and 20b are provided to separately detect the rotational speeds of the rear wheels 5a and 5b attached to the left and right axles connected via the differential mechanism 6, respectively. The rotation of the axle corresponding to the rear wheels 5a, 5b is transmitted to the encoders 20a, 20b via a chain or the like. At the bottom of the vehicle, substantially at the center of the vehicle body frame 1, a battery 21 is mounted as a power supply such as the traveling drive motor 7 and the steering motor 11, and encoders 20a, 20b are provided below the steering wheel 14a at the center of the vehicle. The traveling distance and direction are calculated from the rotational speeds of the left and right rear wheels 5a and 5b detected by the controller, and the traveling drive motor 7 and the steering motor 11 are controlled in accordance with the preset course information while constantly recognizing the own position. A computer box 16 is mounted. In this embodiment, three laser projectors 23a to 23c are provided at the front end of the upper frame 1a formed so as to protrude forward from the handle 14a, and a pair of laser projectors 23a for position checking are provided. , 23b each emit a laser beam in a direction orthogonal to the center line of the vehicle, that is, right beside the vehicle, and can scan up and down. The other auxiliary laser emitter / receiver 23c is provided only on one side (for example, the left side) of the vehicle, and emits a laser beam obliquely forward of the vehicle and can scan vertically. . The laser beams emitted from the laser projectors 23a to 23c are reflected by a reflecting device REi called a corner cube disposed at appropriate intervals along both sides of the traveling course of the vehicle. Since this corner cube has the property of reflecting incident light in the same direction as the incident direction,
The reflected laser beam reaches the laser projectors 23a to 23c that emitted the laser beam and is detected. As a result, the position of the vehicle can be checked. In addition, since one side (left side in the embodiment) of the vehicle is provided with two laser emitters and receivers, which are directed sideways and obliquely forward, the distance from the corner cube on the left side of the course can be reduced by a kind of triangulation. You can now know. In the vehicle shown in FIG. 1, an input operation device 27 for setting course information from the outside is mounted at a position behind the upper handle 14a of the upper frame 1a. In addition, a storage device for storing the course information and the like,
It is mounted together with a computer in a computer box 16. At a position above the differential mechanism 6 below the input operation device 27, a control device including a counter for counting pulse signals from the encoders 20a and 20b, an I / O interface circuit and the like is provided.
A box 18 is provided. Further, the input operation device 27
A key 19 for turning on and off a main switch for turning on a power supply is attached to a lower part of the power switch. FIGS. 2 and 3 show a specific example of a device for switching between automatic steering and manual steering, that is, a device for switching one of the steering motor 11 and the handle shaft 14 to the steering shaft 4 in a switchable manner. The structure is shown. A housing 12a of a speed reducer 12 is rotatably supported on a holder 10 fixed to a front end of the body frame 1.
The steering motor 11 is fixed to the upper end of the housing 12a, and can rotate integrally with the housing 12a. An input shaft 12b of the speed reducer 12 is connected to a rotation shaft 11a of the steering motor 11 via a cylindrical coupling 31. Output shaft 12c protruding from the lower end of reducer 12
, The steering shaft 4 is also connected via a coupling 23. A flange 12d is formed on the housing 12a of the speed reducer 12,
Bolts (hereinafter referred to as “el-balls”) 33 having a pair of spherical heads are fixed at positions 180 ° apart from each other on the lower surface of the flange portion 12d, and the lower surface of a plate 14b fixed to the lower portion of the handle shaft 14 Also, a pair of el balls 34, 34 are fixed, and both ends of the links 13, 13 are rotatably connected to the spherical heads of the el balls 33, 33, 34, 34, respectively. Therefore, handle shaft
When the 14 is rotated, the entire housing 12a and the speed reducer 2 rotate by the same angle in the same direction as the handle shaft 14 via the pair of links 13 and 13. And the output shaft 12c of the speed reducer 12
The steering shaft 4 is connected to the steering shaft 4 so that the steering shaft 4
And rotate in a 1: 1 relationship. An engagement recess 12e is formed on the outer periphery of the housing 12a, and the block 4 fixed to the holder 10 corresponding to the engagement recess 12e.
A through hole 40a is formed in the hole 0, and a lock pin 35 is inserted in the through hole 40a. And this lock pin 35
Is moved by the operation of the solenoid 36. When the lock pin 35 is engaged with the engagement recess 12e, the rotation of the housing 12a is prevented, and the rotation of the handle shaft 14 is also prevented. . An engagement recess 32a is formed in the coupling 32 connecting the output shaft 12c of the speed reducer 12 and the steering shaft 4, and a through hole is formed in the block 41 integrated with the speed reducer 12 corresponding to the engagement recess 32a. When the second lock pin 37 is inserted into the through hole and the lock pin 37 is moved by the operation of the solenoid 38 to engage with the engagement recess 32a, the first lock pin 3
The rotation of the housing 12a can be transmitted to the steering shaft 4 via the coupling 32, provided that the 5 is disengaged from the engagement recess 12e. Accordingly, when the first lock pin 35 is removed and the second lock pin 37 is engaged, when the handle 14a is operated, the rotational force of the handle shaft 14 → the link 13 → the housing 12a → the coupling 32 in this order. And the steering shaft 4 rotates. If the first lock pin 35 is locked and the second lock pin 37 is removed, the rotation of the housing 12a is prevented and the rotation of the coupling 32 becomes free, so that the steering motor 11 is rotated. The rotational force of the rotating shaft 11a of the motor 11 is transmitted to the input shaft 12b of the speed reducer 12, and its rotation is internally reduced to 1/30.
It is transmitted to the steering shaft 4 via 2. At this time, the rotation of the handle shaft 14 is prevented. Since there is only one engagement recess 12e, the handle 14a is fixed at the center position. In other words, unless the handle 14a faces front, the first lock pin 35 is
The handle shaft 14 cannot be locked by engaging with the handle shaft 12e. First and second lock pins
Switching means between the manual steering system and the automatic steering system is constituted by 35, 37 and the like. In the above embodiment, the lock pins 35 and 37 are connected to the solenoid 3
Although it is operated at 6,38, it can be configured to be operated manually. In this embodiment, a stepping motor is used as the steering motor 11 to perform open-loop control. An example of the control circuit of the automatic steering system is shown in FIG. 4, and the computer CPU is connected to a motor controller MTC for controlling the drive of the step motor 11 via a parallel i / o controller PIC. When one pulse is input, the motor controller MTC supplies an excitation signal for rotating the motor by one step in the designated direction to the step motor 11. In addition, a timer controller PMC is provided to control the interval (period) of pulses supplied to the step motor 11. The parallel i / o controller PIC, motor controller MTC, timer controller PMC, and the like are provided in a controller box 18 in FIG. 1 showing a mechanical configuration of a vehicle that automatically travels. Next, an example of a specific control procedure of the step motor 11 by the computer CPU will be described. When the computer CPU knows that the steering condition has been established from the course information and the information indicating the current position of the vehicle, first, it determines an appropriate steering direction and steering speed (step). Next, since the speed of the step motor 11 is determined by the interval (cycle) of the drive pulse, the timer controller PM
Set the cycle value data for the appropriate speed for C (step). Then, the timer controller PM
C performs a timing operation based on the cycle value, and sends an interrupt signal to the computer when the set time has elapsed (step). When the computer receives the timer interrupt signal, the computer outputs binary data indicating forward or reverse rotation to the parallel i /
oSend to controller PIC. At the same time, the computer counts and stores "+1" for forward rotation or "-1" for reverse rotation in order to recognize that the forward / reverse rotation signal has been sent (step). Then, returning to the steps again, the steering direction and the speed are obtained based on the cycle data thus far, and the following steps are repeated. Next, an example of a method of determining a steering speed when outputting a steering command from the computer to the step motor 11, that is, a cycle of a drive pulse of the step motor will be described. When driving a step motor for steering, if the angular velocity of the steering shaft is suddenly greatly changed, the tire of the wheel slips on the running surface. Therefore, in this embodiment, when the current steering position where the steering axis is stopped is set to "0" and then the steering axis is turned clockwise or counterclockwise, respectively, as shown in FIG. 5 (A). First, when starting steering toward the target steering angle AD, first, gradually increase the angular velocity, move from a certain point to a constant velocity, and finally gradually decrease the angular velocity to perform the target steering angle. The control to reach is performed. Specifically, as shown in Table 1, the angular velocity can be reduced by increasing the period of the pulse, and the angular velocity can be increased by shortening the period. Further, in the example of Table 1, the rate of change of the angular velocity is initially increased during acceleration, and the rate of change is increased at the end during deceleration, without setting the cycle at equal intervals. Further, when the steering shaft is turning clockwise or counterclockwise, if the steering shaft is to be turned in the opposite direction, that is, in the counterclockwise or clockwise direction, as shown in FIG. As shown in ()), control is performed such that the angular velocity is gradually increased, then gradually increased in the opposite direction, and the speed is shifted to a constant speed. Thereafter, the angular velocity is gradually reduced. By controlling the step motor as described above, a smooth steering operation that does not cause tire slip can be realized as in the case of using the servo motor. According to this embodiment, there is no need to provide an encoder or the like for detecting the number of revolutions for applying feedback to the servomotor, unlike the case where a servomotor is used as the turning drive means, and the turning drive means is provided by a simple control method. Control can be performed, and the configuration of the turning drive means for automatic driving can be simplified. According to the present invention, the following effects (a) to (c) can be obtained by providing the structure described in the claims. (A) The steering apparatus for a vehicle which travels automatically according to the present invention, wherein one of the turning drive means and the handle shaft is connected to the steering shaft via the switching means, and the turning drive means or the handle connected to the steering shaft. Since the steering shaft is turned by the shaft, and at least one rider is provided at a position where the steering wheel can be operated, it is possible to perform automatic steering by the swing driving means or manual steering by the steering wheel. At the time of automatic steering by the turning drive means, the steering shaft and the steering shaft are disconnected from each other, so that the steering wheel does not rotate with the steering shaft, so that the driver can ride on the riding section with confidence. (B) In the steering apparatus for an automatically traveling vehicle according to the present invention, since the turning drive means is constituted by the step motor and the deceleration means for decelerating the rotation of the step motor, the automatic steering can be performed using a small motor. it can. In addition, when the steering shaft is stopped at the time of automatic steering, when the steering is performed by the turning drive means toward the clockwise or counterclockwise target steering angle, the rotation of the step motor is increased gradually at first. In the middle, the speed is made constant, and at the end, the angular speed is gradually reduced to reach the target steering angle.Also, during the turning of the steering axis clockwise or counterclockwise during automatic steering, the turning direction is reversed. When steering by the turning drive means toward the target steering angle of counterclockwise or clockwise, the rotation of the step motor, gradually reduce the angular speed, then gradually increase the angular speed in the reverse direction, At the middle, the speed can be controlled to be constant, and at the end, the angular velocity can be gradually reduced to reach the target steering angle. Operating the can be easily realized. (C) The steering apparatus for an automatically traveling vehicle according to the present invention uses a stepping motor as the turning drive means. Therefore, as in the case of using a servomotor, an encoder or the like for detecting the number of revolutions for applying feedback to the servomotor is used. There is no need to provide such a control, and the turning drive unit can be controlled by a simple control method, so that the configuration of the turning drive unit for automatic driving can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is a side view showing a configuration of a vehicle which automatically travels, and FIG. 2 is a side view showing a part of a steering device. , FIG. 3 is a front view of a main part of the steering device, and FIG. 4 is a block diagram for explaining the configuration of the steering device of an automatically traveling vehicle, and FIGS. 5 (A) and (B).
FIG. 3 is a diagram showing a relationship between a target steering angle and an angular velocity. DESCRIPTION OF SYMBOLS 1 ... Body frame, 2 ... Front wheel, 4 ... Steering shaft 5a, 5b ... Rear wheel, 6 ... Differential mechanism, 7 ... Travel drive motor 9 ... Riding part, 10 ... Holder, 11 ... ... Steering motor 12 ... Reducer, 12a ... Housing, 13 ... Link 14 ... Handle shaft, 14a ... Handle 16 ... Computer box, 20a, 20b ... Encoder 35, 37 ... Lock pin

Claims (1)

(57) [Claims] A plurality of wheels including at least one wheel steered by a steering shaft; a rotation driving unit for rotating any of the plurality of wheels; a turning driving unit for turning the steering shaft; a turning driving unit and a rotation driving unit And a control device that performs the control of the vehicle, the handle shaft is configured to be able to turn by the handle, the turning drive means is configured by a step motor and deceleration means for reducing the rotation of the step motor, One of the turning drive means and the handle shaft is connected to the steering shaft via the switching means, and the steering shaft is turned by the turning drive means or the handle shaft connected to the steering shaft. At least one rider is provided at the position where it can be driven, and when the steering axis is stopped during automatic steering, the clockwise or counterclockwise target steering angle is set. When the steering is performed by the turning drive means, the angular speed of the step motor is gradually increased at first, the speed is made constant in the middle, and the angular speed is gradually decreased at the end to reach the target steering angle, Also, during the turning of the steering axis clockwise or counterclockwise during automatic steering,
When steering is performed by the turning drive means toward a counterclockwise or clockwise target steering angle opposite to the turning direction, the rotation of the step motor is gradually reduced in the reverse direction after gradually reducing the angular velocity. A steering device for an automatically traveling vehicle, wherein a control device is configured to increase the angular velocity, maintain the constant velocity halfway, and gradually reduce the angular velocity at the end to reach a target steering angle.