SPARTA: Multiple Signal Processors for High-Performance Robot Control

Abstract

This paper describes SPARTA: Signal Processor Architecture for Real-Time Applications of robot control. The SPARTA system is a hybrid computer development system which includes: i) program development environment on an IBM VM/CMS mainframe computer; ii) user interface and runtime support on an IBM PC; and iii) real-time computation and I/O using multiple IBM Hermes signal processors situated on the IBM PC bus. The program development environment includes the PLH high-level language for generating efficient real-time Hermes code. The runtime supports symbolic debugging, dynamic loading and linking, and synchronous switching of control algorithms during real-time program execution. The real-time environment includes a distributed operating system which supports foreground and background task execution and real-time data collection and display. The task switching overhead is 0.1 µs, non-pre-emptive, and 1-3.7 µs, when the context is changed by an interrupt (i.e., pre-emptive). A SPARTA system with three Hermes signal processors is currently being used to develop control algorithms for a two-axis fast direct-drive Cartesian robot at sample rates in excess of 10 kHz. A SPARTA system with just one Hermes signal processor, executing a dozen real-time tasks, has achieved a sample rate of 5 kHz for a fully coupled PID control, with nonlinear compensation, for the Eaglet II Cartesian robot (five motors achieving 2 fim linear resolultion and 0.02º angular resolution). © 1989 IEEE