JPS61211177A - Articulated leg mechanism having load reduction mechanism - Google Patents

Abstract

PURPOSE:To reduce the size and the weight of actuator, in an articulated leg mechanism of robot where the load to be applied onto the actuator at single swing side of each articulate within operating range will vary considerably, by providing a mechanism for reducing said load variation. CONSTITUTION:Two leg walking robot is comprised of the right/left ankle sections, the knee section, the waist section and the thigh section to be functioned independently through an actuator. Here, the shaft 25 supported on a rotary member 22 to be fixed with the robot leg is born rotatably on a collar 28 supported through a spring receiver 26 on a frame 23 integral with the robot drum section 13. One end 20A of a spring 20 wound over the collar 28 is stopped to a stopper pin 21 on the spring receiver 26 while the other end 20B is stopped through a bolt 29 to the rotary member 22 thus to constitute a required load reduction mechanism. Consequently, the size and the weight of actuator can be reduced.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a joint drive actuator load reduction mechanism for a multi-joint legged mobile robot, and provides a load reduction mechanism for each joint to reduce the size and weight of the robot. This is what we aim to do.

[Background of the invention]

Conventionally, as a method of reducing the load on the actuator of an articulated robot, there is a method of attaching a canterbalance as shown in, for example, Japanese Patent Laid-Open No. 59-37079. However, this method is intended to reduce a constant load no matter what posture the articulated robot is in, and it is not very effective in reducing load fluctuations on the actuators in response to changes in specific postures. I couldn't get it.

[Purpose of the invention]

An object of the present invention is to provide a load reduction mechanism that can reduce the fluctuation range of the load on the actuator in a joint in a multi-joint leg mechanism where the load on the actuator fluctuates greatly on the unilateral swing side within the range of motion of each joint. This aims to reduce the size and weight of the actuator and the robot body to which this mechanism is applied.

[Summary of the invention]

A walking robot, particularly a bipedal walking robot, will be explained as an application example of the multi-joint leg mechanism.

FIG. 1 is a front conceptual diagram of the bipedal walking robot of the present invention, and FIG. 2 is a right side view thereof. This robot corresponds to the lower body of a human being.

In this robot, a control device 14 for controlling each joint 1 to 12 and a power source 15 for driving each joint 1 to 12 are mounted inside a body portion 13.

The nine leg parts are composed of ankle parts A, B, knee parts C, D, waist parts E, F, thigh parts G, H, and structural members connecting these parts.

The right ankle part A is the joint 1 that moves the torso part 13 in the front-back direction.
and a joint 3 for moving the body portion 13 in the left-right direction. Further, the right knee portion C includes a joint 5 that moves the body portion 13 in the front-back direction. Furthermore, the right waist E is the body part 13
The actuator 7 and the body part 13 that move the
and an actuator 9 that swings from side to side. In addition, the right thigh G includes an actuator 11 that rotates around the thigh.

As for the left foot, the left ankle part B is connected to the actuators 2, 4, . The left knee part has actuator 6 degrees, and the left waist part F has actuators 8, 10 degrees. Left thigh H is actuator 1
It has a structure that operates or rotates in the same way as the right foot.

A conceptual diagram of the walking form of this robot is shown in FIG.

In FIG. 3, in walking mode I, the entire weight of the robot is supported by the right leg 16. In other words, the center of gravity is maintained within the sole surface of the right foot 16.

In walking forms J, L, and M, the 9 center of gravity locus is maintained within the right plantar surface, which is the same as walking form G, and the two robots are supported in the air between walking forms I, J, and L. Further, 1 gait form M in which the left leg 17 is swung out from behind to the front is the first step of a gait form for moving the center of gravity trajectory from the right foot 16 to the left foot 17.

The double center of gravity locus moves to the left foot 17 as a result of the walking forms M, N, and O, which proceed as ○. and.

The transition from walking form O to walking form P means that the robot has completed one step of walking. For the next step, the right foot 16 and left foot 17 are exchanged, and for each joint 1 to 12, the movement step of the left foot 17 is replaced with the right foot 16, and the movement step of the right foot 16 is replaced with the left foot 17. This allows the robot to walk while shifting from a state where the entire weight of the robot is held by the left leg 17 to a state where the entire weight of the robot is held by the right leg 16.

By repeating the above movements, each joint of this robot moves and it is able to walk in a straight line. The same way of thinking can be applied, for example, to changing the direction of a robot.

The same applies to the case of moving in the lateral direction.

The operation of each joint is performed by outputting a control signal from the control device and driving the actuator placed at each joint, thereby operating each joint 1 to 12.
At this time, the fluctuations in the load acting on the joints 1, 9 and 10, for example, are schematically expressed as shown in FIG.

In Figure 4, the vertical axis represents the load (F) acting on the joint.

Further, the horizontal axis represents the joint angle (θ). here.

The point θ=0 indicates the position of the robot's foot when it is standing upright, and when θ〉O, the joints 9 and 10 are in the direction of bending the foot so that the robot is in the inner thigh, that is, the foot on the ground side when the robot is standing on one leg. At θkuO, the foot is bent in a direction such that the joints 9 and 10 are on the outside of the thigh, that is, the foot is raised into space as if standing on one foot. Then, when θ〉0, the load of the torso 13 and the load force for holding the other leg act on the right leg 16 or the left leg 17, while when θ〉O, the right leg 16. Alternatively, the left foot 17 will only have a load acting on its joints that is sufficient to hold its own weight, that is, the weight of the right foot or left foot. As a result, as shown in FIG. 4, the fluctuation characteristics of the load on each joint have a small rise and an absolute value 18 on the 9-sided swing side (the range between θ and 0). However, in the other side (range of θ〉0), its rise and absolute value 19 are very large, and the basic condition for the performance of the actuator applied to the joint is to support this large side load. Become.

As a result, a large-capacity actuator is required, which leads to repeated vicious cycles that lead to larger and heavier joints and the robot as a whole, and further to larger capacity energy sources.

Therefore, to reduce such load in some way,
Improvements are needed so that small actuators can be applied.

[Embodiments of the invention]

Two embodiments of the present invention will be described below with reference to FIGS. 4 to 7.

In order to reduce the load fluctuation range for the load as shown in FIG. 4, we have invented a load reduction mechanism 2 having characteristics as shown in FIG. 5, for example, using a mechanical spring to compensate.

As a result, it can be seen that the load acting on each joint, that is, the output of the actuator, is leveled out and improved as shown in FIG. As a result, the maximum load can be kept small, making it possible to use a small-capacity actuator, and making it possible to reduce the weight of the joint mechanism and robot body.

FIG. 7 will be described as an example for obtaining the load reduction mechanism as described above. FIG. 7 is a view taken along arrows -■ in FIG. 2.

A shaft 25 provided on the pivot member 22 to which the legs 27 (FIGS. 1 and 2) are attached is rotatably attached to the collar 28. The collar 28 is attached to a spring receiver 26 fixed to the frame 23. The stopper pin 21 is fixed to the spring receiver 26 with a screw. The spring 20 is placed inside the frame 23.

It is provided around the collar 28. End 2 of spring 20
0A is bent and engaged with the stopper pin. Further, the end portion 20B of the spring 20 is attached to the shaft 3 at the other end of the zero rotation member 22, which is attached to the rotation member 22 with a bolt 29.
0 (FIG. 1), connected to actuators 9 and 10. Actuators 9, 10 rotate shaft 25 and 309 rotating member 22.

When the rotating member 22 rotates in the R direction, the spring 20 and the stopper pin 21 are connected.

A restoring force is generated in the spring 20. However, the second rotating part 22 is
If it rotates in the direction, the spring 2o and stopper pin 21
are separated, and the restoring force of the spring 20 is no longer applied. As a result, a load reduction mechanism having the spring characteristics shown in FIG. 5 is obtained.

As described above, various types of load reduction mechanisms can be considered, such as a spring mechanism that uses relatively simple mechanical force, and a cylinder mechanism that uses hydraulic pressure, pneumatic pressure, etc.

It should be noted that the present invention is applicable not only to a rotating mechanism but also to a telescopic mechanism having the load characteristics shown in FIG.

〔Effect of the invention〕

By adopting the present invention, the load on the actuator can be reduced, and the actuator can be made smaller, lighter, and more energy efficient. This makes it possible to further reduce the size, weight, and output of the multi-joint leg mechanism and the robot body.

[Brief explanation of drawings]

FIG. 1 is a front view of the articulated bipedal walking robot of the present invention;
Fig. 2 is a right side view of an articulated bipedal robot, Fig. 3 is a conceptual diagram of the walking form of an articulated bipedal robot, and Fig. 4 shows the load acting on the joints when the present invention is not used. This shows the characteristics of joint angles. Further, FIG. 5 is a characteristic diagram of the load reduction mechanism to be used in the present invention, and FIG. 6 is a diagram showing the characteristics of the load acting on the joint and the joint angle when the present invention is used. Furthermore, Fig. 7 shows the structure of the load reduction mechanism, and Fig. 7 (A) is a view from the ■-■ arrow in Fig. 2, and Fig. 7 (B) is a view from Fig. 7 (A). ■-It is a sectional view. Explanation of symbols 20... Spring 21... Stopper pin 22... Rotating part 23... Frame Figure 1 Figure 3 ■ 4N 5th note 60

Claims (1)

[Claims] 1. Unidirectional load fluctuation (increase) that occurs during leg movement in an articulated leg mechanism, which is one of the robot locomotion technologies.
In response to this, a mechanical load reduction mechanism has been installed to reduce the load on the actuators that directly drive the joints.As a result, the actuators can be made smaller and lighter, and the legs themselves and the robot body can also be made smaller and lighter. An articulated leg mechanism with a load-reducing mechanism.