Kunio Miyawaki

A hybrid drive parallel arm for heavy material handling

This article discusses a hybrid drive parallel arm driven by cables and cylinders in order to design a compact handling arm, thus enlarging its workspace. Our major objective is to develop a dexterous arm capable of controlling six-degree-of-freedom (DOF) motion of heavy materials. The article includes a basic concept of parallel mechanisms with hybrid actuation, comparisons and evaluations of some types of hybrid mechanisms based on its kinematics and statics, and finally introduces a designed prototype arm.

Application of locomotive robot to rescue tasks

The research aim is to apply locomotive robots to rescue tasks, such as searching for sufferers and removing obstacles to save sufferers. The paper discusses the exploitation of arm and leg integrated robots and basic experiments of infrared probing sensor, in the application of rescue tasks. First, the limb mechanism is introduced and discussed in the aspect of locomotion capability and stability in rough terrain of disaster area. Then, the probing sensor is evaluated in the aspect of its detection range and capability. Assuming the sensor is mounted on the tip of robot arm for probing, the probing algorithm is proposed to find quickly and locate precisely a sufferer. The basic experiments have been carried out using a parallel arm to confirm the applicability and the usefulness of the proposed rescue system.

Hybrid drive parallel arm and its motion control

A hybrid cylinder/cable drive parallel arm and its motion control are discussed. The basic idea of the hybrid parallel arm is to make the best use of the mixture of the high power cable drive and the cylinder actuation to obtain a heavy-duty manipulator in construction and ship building applications. A prototype arm has been designed and built based on the analysis and the comparative study of several types of hybrid drive mechanisms, the Stewart platform, and a wire drive mechanism. The tension of wire has to be maintained properly in the hybrid mechanism during its motion. The proposed hybrid arm is a kind of actuation-redundant mechanism and its internal force can be freely controlled. The proposed control algorithm is to give wires proper tension during its motion by exploiting the internal force, The required tension and cylinder force can be obtained by compensating each link position command based on its compliance. The repeatability tests show the effectiveness of the proposed algorithm in maintaining the overall stiffness of the arm.

Implementation of Dual-Arm Cooperative Controll by Exploiting Actuator Back-drivability

This paper presents hybrid position/force control for dualarm cooperation without using any force/torque sensor. The control uses only motor current as force/torque information and exploits motor back-drivability. A key technique in this control is compensation of friction at the motors, for which this paper presents a new method named dithered measurement. Experiments in the paper show that this method works well in order to implement dependable force control.