Design of a scalable real-time robot controller and application to a dexterous manipulator

Research in surgical robots often calls for multi-axis controllers and other I/O hardware for interfacing various devices with computers. As the need for dexterity is increased, the hardware and software interfaces required to support additional joints can become cumbersome and impractical. To facilitate prototyping of robots and experimentation with large numbers of axes, it would be beneficial to have controllers that scale well in this regard. This paper discusses the design of a real-time (one kilohertz) robot controller based on a centralized processing, distributed I/O architecture. We combine powerful yet accessible real-time technologies such as IEEE 1394 (FireWire) and low-latency field programmable gate arrays (FPGAs). The device is developed and used with a real-time operating system, and scalability is demonstrated on a novel snake-like surgical manipulator. Results on a 21-axis prototype suggest that the proposed solution can help increase the viability of complex robots, particularly in education and research. In that spirit, the robot control software libraries have been released as open source, and efforts are underway to release the electronic designs.