JPS6274774A - Control method for leg-with-wheel-type mobile robot - Google Patents

Abstract

PURPOSE:To aim at the improvement of the moving efficiency and the moving accuracy, by computing the rotating angle of wheels due to the movement of the robot body through the rotating angle of joints of respective legs so as to control the rotation of the wheels and thereby eliminating the constraint between respective legs. CONSTITUTION:The captioned robot is provided with a pair of driving wheels 2 at right and left sides respectively, front legs 3 and rear legs 4, wherein wheels 5, 6 equipped with brakes, driving mechanisms and angle detectors are provided at the end of respective legs 3, 4. Further respective legs are to be joint type and joints 3c, 3d and 4c, 4d are provided with driving mechanisms and angle detectors respectively. Upon moving the robot body 1, floating from a running surface by turning the legs at the condition where the wheels 5, 6 are brought in contact with the running surface, wheel angles due to the movement of the robot body 1 are computed with joints angles so as to control the rotation of the wheels 5, 6 such as the wheels 5, 6 are rotated to the extent of the computed rotating angles in order that the constraint due to the rotation of the wheels 5, 6 is eliminated.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is intended to allow movement without any restraining force being applied to each leg.

[Prior Art] A legged and wheeled mobile robot as shown in FIG. 4 has been developed as a robot for inspecting the inside of a nuclear reactor containment vessel, a small robot for inspecting difficult places, and a robot for extreme work. To explain this leg-wheel type mobile robot, a mobile robot main body 1 includes a pair of drive wheels 2 (only one shown in the figure), a pair of front legs 3, and a pair of rear legs 4 (only one shown in the figure). A wheel 5 is attached to the tip of the front leg 3, and a wheel 6 is attached to the tip of the rear leg 4.
a, lower leg 3b and crotch m3c, [It is a two-jointed leg with joints 3d, and 1 between each! i3c and 3d are equipped with a drive mechanism and an angle detector. Similarly, the hind leg 4 is the upper leg 4.
a, lower leg 4b, hip joint 4C9, knee joint 4d 2
It is an articulated type, and each joint 4c, 4d is equipped with a drive mechanism and an angle detector.The wheels 5 and 6 at the end of each leg are equipped with a brake, a drive mechanism, and an angle detector. When the wheel is released and there is no driving force, it rotates due to an external force and becomes a driven wheel.

The rotating mechanism side of the wheel 5 is shown in FIG. 5. As shown in FIG. 5, the rotational force of the motor 7 is transmitted to the wheel 5 via the reducer 7 and the gear train 9, and the wheel 5 rotates. The rotation angle or rotation speed of the wheel 5 is detected by a rotary encoder IC.

Further, the wheels 5 are restrained by brakes 11. The rotation mechanism of the wheel 6 also has a similar configuration.

The leg-wheel type mobile robot with this configuration runs on a flat surface by rotating the wheels 5 and 6, and when there is an obstacle, the legs 3
．． 4 and wheels 5 and 8 in combination to overcome obstacles.

[Problems to be Solved by the Invention] In a legged wheel type mobile robot, the mobile robot main body 1 is floated with the wheels 5 and 6 in contact with the ground, and the mobile robot main body 1 is moved vertically or horizontally. When this happens, the conventional control method has the problem that a restraining force is generated between the legs, making it impossible to perform smooth S movements. Here, the problems of the conventional control method will be explained for each case.

FIG. 6 is an example of vertical movement of a four-legged wheel-type mobile robot according to the conventional method. Figures 6(a) to 6
As the mobile robot main body 1 moves upward in the vertical direction to the state shown in Figure (b), the angle between the legs 3.4 and the wheels 5.6 changes from θf1 to θf2. If the radii of the wheels (auxiliary wheels) 5 and 6 ahead of the 0th leg that change from θ1, to θ,2 are Rf and Rr,
Along with the movement from FIG. 6(a) to FIG. 6(b), the wheel 5 moves by a line f, and the wheel 6 moves by a line. If, u, is expressed by the following formula.

Illusion = Rf (θf1 - θf2) Saki = R, (θ, 1 - θ, 2) In general, Δ sentence; Sentence f - Saki ≠ 0, so if 1 position control is performed, only 6 sentences will change the axle of wheels 5 and 6. A force moves in the direction of reducing the distance between them.

If the friction between the ground 100 and wheels 5 and 6 is small, wheel 5
If the angle 6 is too large, it acts as a restraining force on the joints of the legs 3 and 4, significantly reducing movement efficiency and even damaging them.

FIG. 7 is an example of a horizontal movement operation in a similar manner. In this example, if the distance between the wheels and the distance between the joints are not equal, if≠oblique, the 6th sentence does not become O, and the same phenomenon as in the example of FIG. 6 occurs. Furthermore, even if sentence 1 is phantom and sentence 6 is 0, the front and rear wheels rotate and move by 1f=l in the same direction, so the robot body also moves.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, an object of the present invention is to provide a method for controlling a leg-axle type mobile robot that can move a mobile robot main body without generating a restraining force between the legs.

[Means for Solving the Problems] The present invention, which achieves the above object, calculates the rotation angle of the wheels caused by the movement of the main body from the joint angles of the legs, and actively adjusts the wheels at the tips of the legs to correct it. The feature is that it can be rotated to prevent binding.

[Example] Fig. 1 shows an example of the position control of one leg 3 as an example of the movement method for preventing restraint according to the present invention.Similar control is also performed on the leg 4, and the center position of the wheel 5 9 IJ ahead is shown. is expressed in coordinates (robot coordinate system) with the origin at the hip joint 3C of the mobile robot body 1 and the x and y axes in the horizontal and vertical directions.Then, the angle φ1 of the knee joint @3d and the groin joint 3C at position A is ．． θ
l is calculated using the following formula. Here, sentence 1m is upper 1b13a
It is the length between the joints of l lower 11i3b. (See FIG. 2) At this time, the angle δ1 formed between the floor surface 100 and the lower leg 3b is as follows.

δ18φ1-01 Similarly, 02. φ2. δ2 is found. Even when the wheel 5 rotates, no restraint occurs on the floor surface 100.
and the angle δ between the legs changes in exactly the same way for all legs. Furthermore, even if this condition holds true, the ground contact position of the legs changes as δ changes, and the entire body moves slightly, causing the winding to take place.
÷You can eat at Lu Fat Market on the top of the table.

The case of moving from A to B in FIG. 1 will be described. According to the formula mentioned earlier, θ1. φ1. δl is determined, and the rotation angle γ1 of the wheel 5 with respect to the leg 3 at that position is set as O. Each color θi, φ;, δi on the way to B is found in the same way. Here, in order to correct the rolling of the wheels 5, it is sufficient to rotate γi from the example position by the value of the following equation.

γ1 = δ1 - 61 = (θi - φ1) - (θ1 - φl) If the wheel 5 is continuously rotated according to the above formula for all legs during movement, the tip of the leg will be connected to the hinge at the center of the wheel 5. The movement is similar to that of moving around , and there is no restriction, and movement due to rotation caused by rolling of the wheels 5 can be prevented.

FIG. 3 shows a block diagram of these control systems.

[Effects of the Invention] In a legged and wheeled mobile robot, the present invention can prevent the binding between the legs and the accompanying movement caused by the angle between the legs and the ground changing as the legs move. This can be expected to improve movement efficiency and movement accuracy.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram for explaining the control method of the present invention, Fig. 2 is an explanatory diagram of joint angle calculation, Fig. 3 is a block diagram showing control blocks, and Fig. 4 is a leg wheel type moving robot. FIG. 5 is a configuration diagram showing an example of a wheel mechanism, FIGS. 6(a) and (b) are explanatory diagrams showing vertical movement operation, and 7th rgJ
(a) and (b) are explanatory diagrams showing a horizontal movement operation. In the drawing, ■ is the main body of the mobile robot, 3.4 is the leg. 3c and 4c are the hip joints, 3d and 4d are the knee joints, 5.6 is the wheel, and 100 is the ground. Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 (a) (b)! 5e:1 Figure 7(a) (b no.

Claims (1)

[Scope of Claims] A mobile robot body is provided with three or more legs each having a plurality of joints each equipped with a drive mechanism and an angle detector, and each having a wheel equipped with a drive mechanism and an angle detector at the end of each leg. A control method for a legged and wheeled mobile robot in which the main body of the mobile robot is lifted off the running surface by rotating the joints with the wheels at the tips of the legs in contact with the running surface. Control of a legged wheel type robot, characterized in that the rotation angle of the wheel caused by the movement of the wheel is calculated from the rotation angle of the joint, and the wheel is rotated by the calculated rotation angle in a direction to eliminate restraint due to rolling of the wheel. Method.