Tetsuo Hagiwara

Development of X-screw: a load-sensitive actuator incorporating a variable transmission

This research deals with the development of a load-sensitive continuously variable transmission designed for use as a linear actuator. This mechanism, named X-screw, has several unique features not found in other transmission systems that make it especially suitable for use as a robotic actuator. X-screw has a transmission ratio that automatically changes in response to the load, making it possible to combine relatively high speed motion under low loads with a large maximum load capacity in a much smaller space and with less complexity, than traditional transmission systems. X-screw also has built-in overload protection since it will stop advancing if the load exceeds a certain value although the motor is able to continue to rotate. Furthermore, X-screw can produce arbitrarily slow linear motion from a high speed input, eliminating the need for bulky gear reductions. Experimental tests conducted with a prototype have confirmed the functionality of this system.

Armrest Joystick -mechanism design and basic experiments-

Manipulators, which are mounted on robots that substitute man at dangerous places like indoors and outdoors disaster sites or mine fields, have been mainly controlled by joysticks. However, joysticks are difficult to manipulate and complex tasks become hard to be done by operators because of a limit and discordance of controlled degree of freedom. Therefore, a controller with high operability like the Master-Slave system is needed, nevertheless conventional controllers are not used in these situations because there is no controller which has compact structures and intuitively controls 3DOF position and 3DOF posture. In this research, we propose a remote controller “Armrest Joystick” of the Master-Slave system which has high portability and operability. The Armrest Joystick is attached to a foldable portable chair and can be carried easily. It consists of a 3DOF position controller with an armrest supporting the operators arm during operations, a 3DOF posture controller and a gripper controller. Furthermore, it has motors for the force feedback on all axes for more intuitive operations. In this paper, we report the basic concept and design of the Armrest Joystick, and the experiments which verify operability and the validity of the force feedback.

Tethered Detachable Hook for the Spiderman Locomotion (Design of the Hook and Its Launching Winch)

This paper introduces a newconcept of “tethered detachable hook (TDH)” and its launching winch. TDH system is the device which will be mounted on a mobile robot and enhances its traversability over extremely hostile terrain by launching detachable hook to nearby objects, producing large traction force by the tether and detaching/recovering the hook to the launcher again. In this paper the authors first of all introduce several prototype models of the TDH.We then discuss the design of latest model which features pneumatic detaching mechanism, the pneumatic launcher and the reel mechanism having three motion states; active rotation, free rotation and braking. Finally, the result of several experiments of constructed TDH model will be explained.