JP2006015462A - Robot system having super-flexible body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a robot system which is equipped with a user-friendly sensing system (sensor system), and has a flexible body having an infinite-dimensional degree of kinetic freedom. <P>SOLUTION: The robot system is formed of the body having the infinite-dimensional degree of kinetic freedom, an actuator 2 for applying power to the body, an internal sensor 3 for detecting a feature value of the body, and a controller 4 for calculating a suitable control input from information from the sensor, and issuing an instruction to the actuator. According to the operation of the robot system, by efficiently selecting the sensing system (sensor system), desired work can be achieved based only on the information of the internal sensor though the robot system is of a super-driving system and a super-deteriorated observing system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a robot system having a flexible body having infinite dimensional degrees of freedom.

Our surroundings are full of materials with extremely high kinematic flexibility. For example, there is no time to enumerate fabric products such as jackets, ties and handkerchiefs, various papers such as copy paper, leather products such as bags, threads, strings, cables, food, plants, etc. The characteristic points of these systems are the following three. First, it has an extremely large kinematic degree of freedom and can be approximated as an infinite dimensional system. In addition, the movable range of each degree of freedom is wide, and it cannot always be linearly approximated. Secondly, it is almost impossible to actuate all degrees of freedom independently, so in most cases it is a very high underactuated system, ie a super underactuated system. Third, it is virtually impossible to sense information on all degrees of freedom, so in most cases it is a very high under observation system, that is, a super inferior observation system. A system with the above characteristics is called a system with a super-flexible body, or a system that is abbreviated as super-flexible.
Looking directly at the features of the super flexible system, it seems to be an extremely difficult system to control as a control system. However, what is surprising is the fact that humans are well manipulating the above ultra-soft materials. Humans usually do not suffer from these handling. Here, the possibility of constructing a system theory of super flexible systems becomes apparent.
Another point to note is the fact that the human body itself, which is a vertebrate, has considerable flexibility and is very flexible. For example, if you anesthetize a vertebrate and realize a state where brain control is not effective, you will realize that this system is truly a super flexible system. As suggested by Russian physiologist Bernstein, vertebrates with extremely flexible bodies have high intelligence, and inflexible exoskeletons such as insects have only realized low intelligence. It is inferred that there is a non-negligible relationship between super flexibility and intelligence.
Based on the above facts, we find that a robot system with a super flexible body is very useful. This is because the development of mechanical systems with dexterous object manipulation capabilities that play an active role in everyday environments and the realization of highly intelligent robot systems can be expected. In addition, it is important from the viewpoint of safety that the robot system has a flexible body as the robot system will be used while sharing the environment with humans.

There are several related research and patents for the realization of a robot system with an ultra-flexible body.
Arisumi et al. Proposed a system in which a robot hand is attached to the tip of a fishing line based on fishing casting (see Non-Patent Document 1). In addition, Ichikawa and Hashimoto are studying string manipulation by attaching a string to the hand of a robot arm (see Non-Patent Document 2). These studies are related to the super-flexible body system, but both use a camera that is an external sensor to detect the features of the super-flexible body. In external sensing, there is a limit to the use and the scope of application is not wide in order to accurately and quickly acquire the features of a super flexible body system. For example, in both cases, the shape of the ultra-flexible body is photographed from the side, and there are strong restrictions on the location of the camera.
Suzuki has applied for a patent on the control method of the underactuated system, named super flexible manipulator (see Patent Document 1). However, in reality, it is not an infinite dimensional system as described here, but a finite dimensional system. Furthermore, since it is assumed that all the degrees of freedom of the finite-dimensional system can be observed, it is difficult to extend it to an infinite-dimensional system.
Arisumi, H., T. Kotoku, K. Komoriya: Swing Motion Control of Casting Manipulation, IEEE ControlSystems, Vol. 19, No. 4, 56/64, 1999. Tomoaki Ichikawa, Atsushi Hashimoto: Dynamic Manipulation of Strings by Robot, 19th Annual Conference of the Robotics Society of Japan, 1243/1244, 2001. JP 2003-266346 A

  The problem to be solved by the present invention is to provide a robot system having a flexible body having an infinite dimensional kinematic degree of freedom and a control method therefor, with an easy-to-use sensory system (sensor system).

Appropriate control input from the body with infinite dimensional kinematic freedom, an actuator that can apply force to the body, an internal sensor that detects the body features, and information from the sensor We propose a robot system consisting of a controller that calculates and commands the actuator.

The internal sensor is, for example, an angular, angular velocity, or angular acceleration sensor with a part of the kinematic freedom of a super flexible body. In some cases, it is a position, velocity or acceleration sensor. Alternatively, it may be a force sensor or a vibration sensor.
The key to realizing an ultra-flexible body system as an actual mechanical system is the development of sensory systems. As described in the background art, in an ultra-flexible body system, it is impossible to sense all the degrees of freedom in the inner world, so an external sensor is used to detect the features of the super-flexible body. It was normal. In the present invention, by using an internal sensor that detects a part of the kinematic degrees of freedom, the minimum necessary for achieving control from among infinite options embedded in the body having infinite dimensional kinematic degrees of freedom. Only the feature quantity of is detected. As a result, the sensory system (sensor system) becomes very simple, and the robot system has a wide range of applications and is easy to use.

The super flexible system has (1) a one-dimensional structure in the three-dimensional space (for example, a thread, a string, a cable, a limb, a trunk, etc.) and (2) a three-dimensional space in the three-dimensional space of the body. (3) 3D structure in 3D space (eg food such as bread dough, clay, skin, etc.) is there. Among them, the 1D structure in the 3D space has many various examples from the viewpoint of manipulation, such as casting manipulation represented by fishing, trapping flying objects with the chameleon tongue, and hitting the top. Do it.

  Lighter robot. The improvement of safety can be expected by flexibility. In addition, the realization of a robot system with dexterity can be expected.

  In the robot system proposed in the present invention, the actuator and controller may be general purpose. As an ultra-flexible body, familiar items such as strings, ropes, and cloth can be used if they have sufficient strength. A general-purpose angle sensor such as a rotary encoder can be used as the internal sensor. The force may be detected by putting a strain gauge on a part of the super flexible body. However, it is desirable that the actuator, controller, and internal sensor do not interfere with the movement of the super flexible body by themselves.

As an example of the robot system and control method of the present invention, the vibration suppression of the flat string is shown.
FIG. 1 shows an embodiment of the robot system of the present invention. 1 is a string which is a one-dimensional super-flexible body in a three-dimensional space, where movement in a plane is allowed. 2 is a direct drive motor, which is an actuator, and can perform translational motion with one horizontal degree of freedom. One end of the string is fixed to this motor. 3 is a rotary encoder which is an internal sensor. The angle of the fixed end with the string motor can be detected. 4 is a controller. Thus, this robot system has an infinite kinematic degree of freedom in the string part, but the actuator degree of freedom is only 1, and it is a super-poor drive system. In addition, the degree of freedom of the sensory system is 1, and it is an extremely inferior observation system that only detects the angle of the fixed end of the string motor.
In the initial state, the string is on the vertical line and is stationary. First, when a positive / negative pulse input as shown in Fig. 2 is given by the actuator, the foundation moves horizontally and stops, and then the string continues to vibrate. The lower part of Fig. 2 shows the simulation results using a 50-degree-of-freedom serial link system, and is a time graph of the potential energy of the string. It can be confirmed that the potential energy is sinusoidal. This indicates that the string is vibrating.
On the other hand, the angular velocity is estimated from the angle of the fixed end with the string motor, and this amount multiplied by the gain is negatively fed back as the motor translational force. This result is shown in FIG. The potential energy quickly converges to the original minimum value, and it can be confirmed that vibration suppression is effectively realized for the string.
In this way, the desired control can be achieved for the infinite-dimensional super flexible body system only by applying the root translation force and detecting the root angle (angular velocity).

  It can be used as a basic part of a home robot system that shares the environment with humans.

It is explanatory drawing of an Example. It is a figure explaining the response of the system when control is not performed. The top is a time graph of the input translational force applied to the system. The bottom is a time graph of the potential energy of the system. The potential energy changes sinusoidally and you can see how the string vibrates. It is a figure explaining the control result by the robot system of the present invention. As in Fig. 2, the upper graph shows the input translational force applied to the system, and the lower graph shows the potential energy of the system. Control starts from 2 seconds. It can be confirmed that the potential energy has been reduced to the minimum value and that the flat string has been successfully attenuated.

Explanation of symbols

1 One-dimensional super flexible body (string) in three-dimensional space
2 Actuator (1-axis direct drive slider)
3 Sensor (rotary encoder)
4 Controller

Claims (8)

Appropriate control input from the body with infinite dimensional kinematic freedom, an actuator that can apply force to the body, an internal sensor that detects the body features, and information from the sensor A robot system consisting of a controller that calculates and commands the actuator. The robot system according to claim 1, wherein the internal sensor is an angle, angular velocity or angular acceleration sensor of a part of the kinematic freedom of the body. The robot system according to claim 1, wherein the inner world sensor is a position, velocity or acceleration sensor of a part of the kinematic freedom of the body. The robot system according to claim 1, wherein the inner world sensor is a force or vibration sensor that is a part of the degree of freedom of kinematics of the body. The robot system according to claim 1, wherein a body of the robot system has a one-dimensional structure in a three-dimensional space such as a string. The robot system according to claim 1, wherein a body of the robot system has a two-dimensional structure in a three-dimensional space such as cloth. The robot system according to claim 1, wherein the body of the robot system has a three-dimensional structure in a three-dimensional space such as clay. Control that attenuates body vibration for a robot system comprising an actuator that can apply a force to one end of a body having a one-dimensional structure in the three-dimensional space, and an angle sensor or a force sensor attached to the same end. Control method to realize