Performance improvement of networked Just-In-Time control for pneumatic artificial muscles

Here we present techniques for improving the performance of our previously proposed networked Just-In-Time (JIT) control, which is based on a client-server architecture via the Internet. In this control, a database for the JIT control is stored on a server and shared with clients. The clients communicate mutually with the server through the Internet at a constant interval, and they feed control commands to their respective plants. However, since the communication between a client and a server involves a time delay, and since the overgrowth of a database prolongs the time required to process data, in the present study an algorithm for storing data in a database and for handling data of the database in a shorter time was incorporated into the server. In addition, because a longer communication time extends the interval for adding a JIT control command and causes performance deterioration, we vectorized the sending and receiving control commands to reduce such deterioration. The experimental results for a pneumatic artificial muscle test apparatus showed that the control system with the proposed techniques achieved higher performance than that developed in our previous work.