This chapter will focus on the motion control of robotic rigid manipulators. In other words, this chapter does not treat themotion control ofmobile robots, flexible manipulators, and manipulators with elastic joints. The main challenge in the motion control problem of rigid manipulators is the complexity of their dynamics and uncertainties. The former results from nonlinearity and coupling in the robot manipulators. The latter is twofold: structured and unstructured. Structured uncertainty means imprecise knowledge of the dynamic parameters and will be touched upon in this chapter, whereas unstructured uncertainty results from joint and link flexibility, actuator dynamics, friction, sensor noise, and unknown environment dynamics, and will be treated in other chapters. In this chapter, we begin with an introduction to motion control of robot manipulators from a fundamental viewpoint, followed by a survey and brief review of the relevant advanced materials. Specifically, the dynamic model and useful properties of robot manipulators are recalled in Sect. 8.1. The joint and operational space control approaches, two different viewpoints on control of robot manipulators, are compared in Sect. 8.2. Independent joint control and proportional– integral–derivative (PID) control, widely adopted in the field of industrial robots, are presented in Sects. 8.3 and 8.4, respectively. Tracking control, based on feedback linearization, is introduced in Sect. 8.5. The computed-torque control and its variants are described in Sect. 8.6. Adaptive control is introduced in Sect. 8.7 to solve the problem of structural uncertainty, whereas the optimality and robustness issues are covered in Sect. 8.8. To compute suitable set point signals as input values for these motion controllers, Sect. 8.9 introduces reference trajectory planning concepts. Since most controllers of robotmanipulators are implemented by using microprocessors, the issues of digital implementation are discussed in Sect. 8.10. Finally, learning control, one popular approach to intelligent control, is illustrated in Sect. 8.11.
JediBot - Experiments in human-robot sword-fighting
Author Torsten Kröger, Ken Oslund, Tim Jenkins, Dan Torczynski, Nicholas Hippenmeyer, Radu Bogdan Rusu, Oussama Khatib
Video ID : 759
Real-world sword-fighting between human opponents requires extreme agility, fast reaction time and dynamic perception capabilities. This video shows experimental results achieved with a 3-D vision system and a highly reactive control architecture which allowfs a robot to sword fight against human opponents. An online trajectory generator is used as an intermediate layer between low-level trajectory-following controllers and high-level visual perception. This architecture enables robots to react nearly instantaneously to the unpredictable human motions perceived by the vision system as well as to sudden sword contacts detected by force and torque sensors. Results show how smooth and highly dynamic motions are generated on-the-fly while using the vision and force/torque sensor signals in the feedback loops of the robot-motion controller.
Reference:
T. Kröger, K. Oslund, T. Jenkins, D. Torczynski, N. Hippenmeyer, R. B. Rusu, O. Khatib: JediBot - Experiments in human-robot sword-fighting, Proc. Int. Symp. Exp. Robot., Québec City (2012)