Mechanism Design Of Robonaut Head And Research On Its Object Tracing Control Method

"Robonaut", the integration of robot technology and space technology, is one of the most important developmental directions in the future. It can replace people to go to space to finish some certain maintenance. As self-subject"Robonaut"of the State Key Laboratory of Robotics and System, the structure of the 3 Degree Of Freedom (DOF) head of"Robonaut"is designed in this paper, and the control method of object tracing is also stated(proposed). The system can also provide active vision for"Robonaut".At the beginning of this paper, the design principle and performance parameters are proposed according to the task. Furthermore, the mechanical system is introduced in detail, especially for the reduction of the transmission gap generated due to the bevel gear differential mechanism, the adjust method is designed, so that the transmission of the system is smoother and the precision of the position control is higher. At the same time, the integration of the electric system, the visual system and the mechanical system is briefly introduced. The whole head system with 3-DOF (pitching, swing and rolling), is 1.2 kilogram weight as the same size as human.Based on the accomplishment of the system design, the direct kinematics is studied and combined with vision information to obtain the absolute coordinate of the object. Furthermore, depending on whether the view of the object is blocked by the barrier in front of the head, each unique analytical solution of inverse kinematics is given. Based on the traditional Paul planning, a new method named Quartic Polynomial—Line planning is proposed. This method can help the executive agencies evaluate the velocity performance from the last planning cycle. As a result, at each time node of the planning cycle, the actuator can get the expected position precisely and the motion is continuous and smooth during the tracking process.Contraposing the error of the creating model and the uncertainty of the motorial object, Integral Sliding Mode control, with high accuracy and strong robustness, is introduced in this paper. Meanwhile a new method named proportional-switch function method is proposed to alleviate chattering of Integral Sliding Mode control, and the effect of tracing precision and chattering acuteness caused by the parameter is analyzed. The simulation through MATLAB/Simulink indicates that this method can bate the chattering effectively. Furthermore, the simulation validates the effect of choosing different parameter to the results, which supplies the foundation for experiments.In the end, the joint position control experiments and the active vision tracking experiments are accomplished on the head system that has been developed in this paper. The results demonstrate the validity of trajectory planning method and dynamic control approach. The strategy, based on position control ,which tries to keep the center of the table-tennis ball in the middle of optical axis of both eyes, is adopted to realize the real time tracking of a randomly move table-tennis ball within a given speed range.