Masao Obama

Multijoint Inspection Robot

Developing a remote inspection system is an urgent necessity for reducing the down time of facility and occupational radiation exposure to inspection personnel in nuclear facilities.

Development of a multi-fingered robot hand with fingertip tactile sensors

The authors are developing a multifingered robot hand which is modeled on a human hand. The aim is to identify the technologies necessary for this type of robot hand. The hand consists of 4 fingers, each with 4 joints actuated by DC motors via wires. The hand is attached to the tip of a 6-degree-of-freedom arm. The fingers and the arm are controlled by 6 32-bit microprocessor boards. Each finger has a tactile sensor on the fingertip. This consisting of a silicone rubber cap with a cavity filled with an incompressible fluid. Using these sensors and potentiometers mounted at one side of each joint, contact forces and positions of the fingertips are controlled. Three or four fingers grasp an object cooperatively when each finger is force-controlled using the tactile sensors independently. Evaluation tests of the position and the force control were executed, and experiments requiring the robot hand to pick up a pen and write characters were conducted.

An unilateral master-slave hand system with a force-controlled slave hand

We have developed a new unilateral master-slave hand system. The master system consists of a master arm which has a 3-DOF parallel link mechanism and a 3-DOF wrist mechanism, and a dataglove that is usually used for a virtual reality system. The slave system has a 6-DOF arm and a 16-DOF four-fingered hand. In general, a slave system is controlled by position with reference to a master system position. In this system, when an operator makes the slave system work on a complicated task, he must look at the slave carefully and let his arm and hand manipulate discretely. In the new master-slave system, each finger of the slave hand has a fingertip tactile sensor, and it is controlled by position and force. When an operator has knowledge of a task and handling objects and sets the slave fingertip stiffness, the operation can be performed easily by handling the master arm and hand to a rough position.

Design and test of a multi-joint remote manipulator for use in high vacuum

Abstract A multi joint remote manipulator was considered for use for the inspection of in-vessel components of fusion devices. In designing the in-vacuum manipulator, the major technical issues are the selection of lubrication methods and materials for movable parts and the introduction of extrication mechanisms which work in case of accidental failures. A performance test was made on a single joint with two axes. A special hydrocarbon grease was used as the lubricant since no solid lubricant materials endure the strong forces on the gears of the joint. Wire made from shape-memory alloy was utilized for the extrication mechanism. It has been demonstrated that the manipulator works well, in vacuum, for more than 1400 h.