A Study on the Closed Loop Robot Arm Control System Using SEMG

Abstract

In this study, we use SEMG(Surface EMG) that can be derived from the skin surface in order to develop the system which can operate an artificial hand like as a human hand. The previous developed system used a pull solenoid to display grip power to the user. Using this display, the system could feed back grip power to the user. However, from results of experiments it was apparent that more precise resolution of the display is necessary. From these reasons the new grip power display which uses a manchette in order to display the grip power by air pressure has been experimentally developed. A manchette is an air bag which is used at a blood pressure meter in order to put pressure on the upper arm. We thought that new system can display grip power easier than previous system.

In our new system, SEMG of 48 channels are measured from forearm by using a multi-channel electrode. Measured SEMGs are amplified 4000 times, and converted to digital value in a personal computer. In a PC, users hand motion is estimated by using measured SEMGs. If the estimated result is ”grip”, user’s grip power is calculated using amplitude of measured SEMGs. The grip force of a robot hand (or an artificial hand) is controlled based on a calculating result. A force sensor is set on a robot hand and the output of the sensor is analyzed in a one-chip microprocessor. And then based on analyzed result our new grip power display presents grip power of a robot hand as the air pressure of a manchette. In this paper, we will describe about our new developed system and the results of experiments using our new system.