The purpose of this research is for the control of the rotational maneuvers of a robot in midair. The methods of rotational maneuvers divide into 2 groups. One group uses nonzero initial angular momentum, and the other group uses zero angular momentum. In this paper the authors confirm experimentally that a robot can turn over with zero angular momentum without any external forces. And the control method of the rotational maneuvers of a jumping robot in midair is discussed. Rotational maneuvers are made up by a change of the inertia moment of the robot about the axis of the center of gravity. The authors also propose a way to calculate joint trajectories of the robot approximately by giving the initial and the final value of its configuration angles and joint variables.
This article presents a method to determine the minimum set of dynamics parameters of manipulators. It is based on a new concept ’τi (i-th joint torque) -identifiablity’ to classify the dynamics parameters. The method permits the determination of all the minimum dynamics parameters which can be used directly to the Newton-Euler Formulations. It also presents an algorithm for efficient computation of inverse dynamics of manipulators using the minimum set. The computational efficiency of the Algorithm is compared with other published methods.
The purpose of this paper is to propose a new method of the adaptive grasping for multifingered hands with the constraints of static friction and the joint torques, under the repeated manipulation tasks. First, the manipulating and grasping forces of two fingered hands and the dynamic manipulation/grasping controller based on these forces, which have been proposed by authors, are introduced. This controller makes it possible to be given the desired grasp parameter which determine the grasping force, in spite of the desired trajectory of the object. Second, the scalar functions for evaluation of the manipulation and the grasping are defined, and the effects on them by the given grasp parameter are shown. Then, a new algorithm of the adaptive grasping based on these functions is proposed. This algorithm realizes the desired manipulation without slip of the fingertips, adjusting the grasp parameter to the specified manipulation task. Finally, the effectiveness of the proposed method is shown by several experiments.
A method of compliance control for a redundant robotic arm was proposed. The method is constructed by combining two different compliance control scheme ; the fundamental compliance control in the joint space and the adjusting compliance control in operational space. One of the features of the proposed method is to achieve both the desired compliance condition in the operational space and the unique determination of the redundant manipulator configuration. Another feature of it is that the inverse kinematic solution of the redundant manipulator was obtained according only to fundamental compliance parameters. -Also, how to control the trajectory of the end-effector was intro-duced. The inverse kinematics solution is similar to be obtained from the pseudo-inverse Jacobian matrix with a weight matrix. However, it has a different benefit benefit from the pseud-inverse approach, because it provides a function of adjusting the end-effector compliance as well as the inverse kinematics solution. Through experiments using a manufactured four d. o. f. robotic arm with redundancy, the effectiveness of the method was confirmed.
The paper describes an identification method of the dynamics of robot. In the proposed method, two observers are constructed in the joint space. One is used to realize the robust motion controller which is unsensitive against the disturbance torque. The other is used to estimate the dynamics of robot. First, the disturbance observer is introduced from the physical point of view. Then the disturbance torque is also defined from the dynamic model derived from the Euler-Lagrange equations and the model of motor. Secondly, the identification method of the robot dynamics is explained. Several numerical and experimental results are shown to confirm the validity of the dynamic model established by the proposed method. The paper also shows the feasibility of the estimation of reaction torque by using the established dynamic model and the disturbance observer.
In this paper, a macro-micro manipulator system is proposed to realize the trajectory tracking control of a flexible manipulator system. This system has a flexible manipulator as a macro part and a rigid small manipulator on macro's tip as a micro part. A flexible manipulator can move in wide range of space while can not realize precise tracking purpose. The micro manipulator is then used to compensate the tracking eror due to the deformation of the macro manipulator. First, the concepts of compensatability and compensatability measure for the macro-micro manipulator system are introduced. Second, considering the redundancy of the system, path planning is discussed to keep the compensatability measure as large as possible during the whole work phase. Then, a quasi-static trajectory tracking control system is proposed to realize the planned path. Simulation results show the effectiveness of the proposed method.
We propose a method to make a mobile robot push a box from one place to another. First, we defined the circumferential conditions and derived the equations of motion for a robot and a pushed object. The validity of the proposed dynamic equations have been proved by the experiments. We adopt the simplest goal seeking strategy for robot's motor control. The objective of control is to direct a pushed object toward the goal point. Using a spline curve the robot tries to carry the box toward the goal. Many experiments have been done, which proved the feasibility of our proposals.
This report proposes a method for controlling the position and orientation of a manipulator mounted on an autonomous mobile robot. Experimental results show that the end effector of the manipulator can be maintained in a desired position and orientation. Thus, in practical use, materials can be transferred while the robot is moving, which will contribute to revolutional enhancement of material handling efficiency.
It is well known that by introducing coordinated motions of an arc welding robot and a positioning table, most desirable arc welding performance could be obtained. The reason is that the coordinated motions enabled the welding torch and the workpiece to have desirable configurations considering effects of the gravity. In order to realize coordinated motions, a high accuracy of the robot is required. Therefore, force sensors and vision sensors to compensate mechanical errors are often introduced. In this paper we describe a system to realize coordinated motions by employing a teaching-playback robot. Due to the feature of teaching-playback robots that mechanical errors are readily compensated by the operator during the teaching task, satisfactory coordinated motions could be realized without using any additional sensors. Furthermore, a teaching method to specify coordinated motion is described. By using this teaching method, teaching tasks of coordinated motions could be performed effectively. Experimental results reveal the applicability of our robot system to the arc welding tasks.