英文摘要 | Playing table tennis using a robot is one of the advanced performances by robots, which has become an active and challenging research topic in the field of robotics. At present, several foreign and domestic research communities have carried out the related researches. Most of the developed prototypes can strike the ball without spin. The robotic system is a whole one, which refers to the recognition of fast moving objects, trajectory prediction, motion planning, intelligent control and so on. The studies of the robot contribute to our further investigation of perceptional and control problems. Moreover, the research results could provide reference points for other fields with similar theoretical and application backgrounds. Aiming at a 5 degree-of-freedoms table tennis robot, the intelligent control and the strategies involved in the striking process are explored in this thesis. Some relevant topics such as rotational velocity estimation of the table tennis ball, trajectory prediction,racket motion control and striking strategies are discussed. The main contributions of this thesis include following issues: Firstly, a trajectory prediction method for the spinning ball is proposed. A fuzzy filter is designed for noise reduction before prediction. Based on the analysis of forces acting on the flying ball, a flying model is developed, based on which, the ball's rotational velocity is estimated. With the concept of restitution coefficient, an analytic rebound model is deduced, which is used for analyzing the relationship between different components of the flying and rotational velocities before and after rebound. On the basis of the relationship, the velocity of the ball after rebound is calculated using experience data, and then the trajectory of the spinning ball can be predicted. Secondly, based on the self-tuning fuzzy algorithm, a model of computing the desired outgoing velocity of the ball is developed, which combines the physical model with experience data. According to the simplified physical model of the ball, the outgoing velocity could be numerically solved under the two separate conditions of the determined landing velocity and the optimal flying angle. The influence of the desired velocity on the error between the actual landing point and the desired point is analyzed, and accordingly the velocity is tuned using the fuzzy algorithm after the landing point is predicted. Thirdly, the factors that affect striking point selection are il... |
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