JP2007145108A - Method for controlling turn of traveling vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein a conventional traveling vehicle having individually drivable wheels may not make a turn due to insufficient torque when performing a ultra-pivotal brake turning. <P>SOLUTION: When making a turn of a traveling vehicle 1 having right and left front wheels 3 and rear wheels 4 which are individually drivable, and a manipulator 5 to be developed forward of a vehicle body, the manipulator 5 is developed forward of the vehicle body to shift the center of gravity of the vehicle body forward of the vehicle body, and the right and left front wheels 3, 3 are driven opposite to each other. In this turn control method, the distance from the center of gravity of the vehicle body to the front wheels 3 is reduced to enable the rotation with a low torque, and the resistance at the rear wheels 4 and the friction force with the ground are reduced to enable a smooth ultra-pivotal brake turning even by a driving motor 7 of the relatively small output. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a turning control method for a traveling vehicle that is used when a direction is changed in a traveling vehicle that travels by individually drivable wheels.

  2. Description of the Related Art Conventionally, as a traveling vehicle provided with individually drivable wheels, an unmanned traveling robot for the purpose of reconnaissance, monitoring, dangerous substance processing, planetary exploration, and the like is well known (Patent Document 1). This type of traveling vehicle is required to have a simplified structure, light weight, good traveling performance on rough terrain, and the like, and employs a configuration in which each wheel is rotated by an individual driving motor.

  When the traveling vehicle as described above changes its direction, it rotates on the spot by rotating the left and right wheels in opposite directions with an appropriate rotational difference so that the center of the vehicle body is the turning center. A ground turn can be performed. In other words, when turning the direction, by turning with a skid steering system that does not involve the steering of the wheel, the steering device is not required, the structure is simplified and the weight is reduced, and the direction is changed in a narrow place. It is possible.

JP-A-7-156898

  However, in a traveling vehicle such as that described above, when performing a super turn, there is a side slip of the wheel, so the frictional force between the wheel and the ground and the distance from the center of gravity of the vehicle body to the wheel (moment about the center of gravity) The torque of the wheel is greatly affected, and the larger the frictional force and distance, the greater the torque required.

  For this reason, in a conventional traveling vehicle, it is difficult to control the super turning angle because of the large torque required, or it becomes impossible to turn due to insufficient torque, that is, insufficient output of the driving motor, Motors and motor amplifiers may generate heat and break down due to overcurrent, and if a high-power drive motor is used to solve the shortage of torque, this is contrary to the simplification and weight reduction of the structure. It was a problem to solve such a problem.

  The present invention has been made paying attention to the above-mentioned conventional problems, and in a traveling vehicle having left and right front wheels and rear wheels that can be individually driven, even a relatively small output drive motor is smooth. It is an object of the present invention to provide a turning control method for a traveling vehicle capable of performing a super turn.

  The turning control method for a traveling vehicle according to the present invention is a method for turning a traveling vehicle having left and right front and rear wheels that can be individually driven and a functional unit movable in the longitudinal direction of the vehicle body. In such a traveling vehicle, the center of gravity of the vehicle body is located between the front and rear wheels. Therefore, the functional unit is moved in one of the front direction and the rear direction of the vehicle body to move the center of gravity of the vehicle body, and more preferably, the center of gravity of the vehicle body is moved with the axle center of either the front wheel or the rear wheel as the movement limit. In addition, at least one of the front wheel and the rear wheel that is close to the center of gravity of the vehicle body is rotationally driven in the opposite direction on the left and right, and the above configuration is used as a means for solving the conventional problems.

  In the turning control method for a traveling vehicle of the present invention, as a more preferred embodiment, the functional unit can be deployed at least in the front direction of the vehicle body and has a function of holding an object. It is characterized by moving the center of gravity of the vehicle body in the forward direction of the vehicle body by deploying in the direction, and further includes a drive motor that individually rotates and drives the front and rear wheels, and measures the current value of the drive motor, When the current value exceeds a predetermined value, the movement amount of the center of gravity of the vehicle body is increased.

  According to the turning control method for a traveling vehicle of the present invention, the center of gravity of the vehicle body is moved in one of the forward direction and the backward direction of the vehicle body in accordance with the movement of the functional unit, and the wheels close to the center of gravity of the vehicle body are driven to rotate in the opposite directions on the left and right. This reduces the distance from the center of gravity of the vehicle body to the wheel and turns around the center of gravity of the vehicle body. Rotational drive is possible, and the drag is reduced at the wheel far from the center of gravity of the vehicle body, and the frictional force with the ground is also reduced. As a result, it is possible to smoothly perform super turning even with a relatively small output drive motor, and it becomes easy to control the super turning angle as the torque is reduced. By rotating both of the rear wheels in the opposite directions on the left and right, it is possible to perform a smoother super turn.

  Further, the turning control method for a traveling vehicle of the present invention can use an existing manipulator or a power shovel as a functional unit that can be deployed at least in the front direction of the vehicle body and has a function of holding an object. Without adding a dedicated configuration for moving the center of gravity, the amount of movement of the center of gravity of the vehicle body can be adjusted by the amount of expansion of the functional part, and appropriate objects such as rocks can be moved with the hand part of the manipulator or the bucket of the power shovel. The movement amount of the center of gravity of the vehicle body can also be adjusted by holding it.

  Furthermore, the turning control method for a traveling vehicle according to the present invention measures the current value of a driving motor that individually rotates and drives the front wheels and the rear wheels, and increases the movement amount of the vehicle body center of gravity when the current value exceeds a predetermined value. This makes it possible to reduce the distance from the center of gravity of the vehicle body to the wheel further when the overload occurs in the drive motor in a state where turning is difficult, further reducing the amount of side slip of the wheel near the vehicle body center of gravity, and It is possible to further reduce the drag of the wheel far from the heart and the frictional force with the ground, which makes smooth turning of the ground and more reliably prevent the drive motor and its control equipment from being damaged by overcurrent. Can be prevented.

  Hereinafter, an embodiment of a turning control method for a traveling vehicle according to the present invention will be described with reference to the drawings.

  A traveling vehicle 1 shown in FIG. 1 includes a flat, substantially rectangular parallelepiped vehicle body 2, left and right front wheels 3, 3 and rear wheels 4, 4, a manipulator 5 as a functional unit movable in the longitudinal direction of the vehicle body, and a control device. 6, and the front wheels 3 and the rear wheels 4 are respectively rotated by individual drive motors 7.

  The traveling vehicle 1 is remotely operated and includes at least a camera for monitoring the front, a transmitter / receiver, a battery as a power source of each device, and the like, as well as the direction and inclination of the vehicle body 2, wheels 3, 4 includes sensors for detecting the rotation status of 4, the operating status of the manipulator 5, the current value of the drive motor 7, and the like.

  The manipulator 5 is provided at the center of the front portion of the vehicle body 2, and includes a first joint portion 5a connected to the vehicle body 2, a first arm 5b having a base end connected to the first joint portion 5a, and a first arm 5b. A second joint 5c provided at the distal end, a second arm 5d having a proximal end coupled to the second joint 5c, a third joint 5e provided at the distal end of the second arm 5d, and a third joint 5e. A clamp-like hand portion 5f provided at the tip is provided.

  That is, as shown in FIG. 2, the manipulator 5 that is a functional unit can be expanded at least in the front direction of the vehicle body, and has a function of holding an object, that is, a hand unit 5f that holds and releases the object M indicated by a virtual line in the drawing. And can be freely operated by rotating the joint portions 5a, 5c, and 5e.

  The traveling vehicle 1 having the above configuration has a uniform left and right weight balance. When the manipulator 5 is folded on the top of the vehicle body 2 as shown in FIG. 1A, the vehicle body 2 as shown in FIG. The vehicle body has a center of gravity G0 at substantially the center position thereof, and the front wheels 3 and the rear wheels 4 are driven to rotate forward by the respective drive motors 7 to move forward or backward, and the rotational speeds of the left and right front wheels 3 and rear wheels 4 are The course is changed by making different.

  In addition, the traveling vehicle 1 can perform a super turn that turns on the spot by rotationally driving the left and right front wheels 3 and the rear wheels 4 in directions opposite to each other. Will be described with reference to the flowchart of FIG.

  In the turning control method, when a turning command is input in step S1, the driving motors 7 are controlled so that the left and right front wheels 3 and rear wheels 4 are driven to rotate in opposite directions, and turning is started in step S2. Determine whether or not.

  At this time, as shown in FIG. 1B, the traveling vehicle 1 drives the left and right wheels 3 and 4 to rotate at an appropriate rotational speed if the vehicle body center of gravity G0 is located at the center of the vehicle body 2. To turn around the center of gravity G0. If it is determined in step S2 that the turn has started (YES), it is confirmed in step S3 that the turn has been made within a predetermined range (angle), and the turn control is terminated.

  On the other hand, if it is determined in step S2 that the vehicle has not started turning (NO), it is determined in step S4 whether or not the current value of the driving motor 7 has exceeded the threshold value. If it is determined (NO), the process returns to step S1, and if it is determined that it has been exceeded (YES), it is determined whether or not a predetermined time has elapsed in step S5.

  If it is determined in step S5 that the predetermined time has not elapsed (NO), the process returns to step S1, and if it is determined that the predetermined time has elapsed (YES), the center of gravity is moved in step S6. Start.

  That is, in the turning control method, the current value of the driving motor 7 is measured, and the motor current threshold value is set according to the value that causes an overcurrent to the control device such as the driving motor 7 and the motor amplifier. When the traveling vehicle 1 is difficult to turn (step S2 is NO), the current value of the drive motor 7 increases, and therefore when the current value exceeds the threshold value and a predetermined time has elapsed ( In steps S4 and S5, YES, the center of gravity movement is started.

  At this time, the traveling vehicle 1 moves the center of gravity of the vehicle body in the forward direction of the vehicle body (G0 → G1) by deploying the manipulator 5 in the forward direction. As a result, the distance L1 from the vehicle body center of gravity G1 to the front wheel 3 is shorter than the distance L0 from the initial vehicle body center of gravity G0 to the front wheel 3, so that the moment around the center of gravity is reduced in the front wheel 3 Since the amount of skid is reduced, these can be driven to rotate with low torque, and the drag and frictional force with the ground are reduced as the turning moment increases in the rear wheel 4 far from the center of gravity G1 of the vehicle body. As a whole, turning around the center of gravity becomes easy.

  The positions of the vehicle body centroids G0 and G1 can be calculated based on the total weight of the traveling vehicle 1, the weight of the manipulator 5, and the deployment amount. The traveling vehicle 1 can also stop the rotational driving of the rear wheels 4 when making the above-mentioned turning. However, the traveling vehicle 1 can be made smoother by rotationally driving the front wheels 3 and the rear wheels 4 in the opposite directions. Turning is possible.

  Further, in this control method, it is determined whether or not turning is started in step S7. If it is determined that turning is started (YES), the unfolding operation of the manipulator 5 is stopped, and a predetermined range ( Angle) After confirming that the vehicle has made a turn, the turn control is terminated.

  On the other hand, if it is determined in step S7 that the vehicle has not started turning (NO), the process returns to step S6 to increase the movement amount of the vehicle body center of gravity. At this time, the movement of the center of gravity of the vehicle body, that is, the forward deployment of the manipulator 5 may be performed intermittently or continuously, and the movement amount of the center of gravity of the vehicle body can be easily adjusted by the amount of deployment. it can.

  Further, since the traveling vehicle 1 includes the manipulator 5 having the hand portion 5f, in addition to the development of the manipulator 5, as shown in FIG. 2, the hand portion 5f grips an object M such as a rock. In addition, the amount of movement of the center of gravity of the vehicle body can be easily adjusted.

  Further, when the vehicle body center of gravity is moved as described above, the distance from the vehicle body center of gravity to the front wheel 3 is minimized when the vehicle body center of gravity (GA) reaches the axle center of the left and right front wheels 3, 3. The axle center may be the limit of movement of the center of gravity of the vehicle body, but is not limited to this.

  Thus, according to the turning control method of the traveling vehicle 1 described above, it is possible to turn at a low torque by moving the center of gravity of the vehicle body only by adjusting the deployment amount of the manipulator 5, so that a relatively small output can be obtained. Even if the drive motor 7 is used, it is possible to smoothly perform super-revolution, and as the torque is reduced, the super-revolution angle can be easily controlled. For example, the total weight of the traveling vehicle 1 is 35. When the load is about 40 kg, it is possible to perform a smooth super turn using the drive motor 7 with an output of 250 W and a maximum current of 20 A. At the same time, the drive motor 7 and its control device are It is possible to prevent damage.

  In the above embodiment, the state in which the manipulator 5 is folded above the vehicle body 2 as shown in FIG. 1 is described as an initial state. However, the attitude of the manipulator 5 at the start of turning is not particularly related, and how the manipulator 5 works. Even if the posture is different, the same turning control can be performed only by changing the position of the initial center of gravity of the vehicle body.

  Further, the traveling vehicle to which the turning control method of the present invention can be applied is not limited to the above-described embodiment, and a vehicle having an intermediate wheel between the front wheel 3 and the rear wheel 4, Both a front part and a rear part of the vehicle body may be provided with functional units such as a manipulator and a power shovel, and the movement of the center of gravity of the vehicle body is not limited to the front direction of the vehicle body as in the above embodiment, but may be the rear direction of the vehicle body.

  In addition, it is not impossible to use weights that can move in the longitudinal direction of the vehicle body, for example, but this type of traveling vehicle originally requires a simplified structure and light weight. Therefore, it is desirable to use an existing device as a functional unit as in the above embodiment.

It is the side view (a) and top view (b) which show an example of the traveling vehicle to which the turning control method of this invention is applied. It is a side view of the traveling vehicle which shows the state which developed the manipulator. It is a flowchart explaining a turning control method.

Explanation of symbols

1 traveling vehicle 2 vehicle body 3 front wheel 4 rear wheel 5 manipulator (function part)
7 Drive motor

Claims (3)

  When turning a traveling vehicle with left and right front wheels and rear wheels that can be individually driven and a functional unit movable in the longitudinal direction of the vehicle body, the functional unit is moved in either the front direction or the rear direction of the vehicle body. And a rotation control method for the traveling vehicle, wherein at least one of the front wheels and the rear wheels that is close to the center of gravity of the vehicle body is rotationally driven in the opposite direction from side to side.   The functional unit can be expanded at least in the front direction of the vehicle body and has a function of holding an object, and the center of gravity of the vehicle body is moved in the forward direction of the vehicle body by expanding the functional unit in the forward direction of the vehicle body. The turning control method for a traveling vehicle according to claim 1.   It is equipped with a drive motor that individually drives the front and rear wheels to measure the current value of the drive motor, and when the current value exceeds a predetermined value, the amount of movement of the vehicle body center of gravity is increased. A turning control method for a traveling vehicle according to claim 1 or 2.

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