A communicating Thread -CT- case study: JIWY

Abstract

This JIWY demonstrator is constructed in the context of the development of a design framework and software tools to efficiently support mechatronic engineers in developing sophisticated control computer code out of a set control laws. We use the CSP-based Communicating Threads -CT- library as the software communication layer, our hard real-time "virtual machine". JIWY (just a soundful name) is a little tabletop robot with 2 rotational degrees of freedom and a camera as its "end effector", controlled via a joystick on a PC running Real-Time Linux. The control laws are stepwise refined to obtain the control software, enhancing the control-law block diagrams to CSP-diagrams, showing the communication and composition properties of the control software. Enhancements like adding homing and end stops for safety can easily be added in the CSP-diagrams, without adapting the control law design. This shows the orthogonality of the design steps. State charts were not needed to express all functionality, which leaves the design simple. The prize of this elegance, namely performance, has as yet not been investigated.