Research On Visual Detection And Batting Decision For 7DOF Tabletennis Robot  Posted on:20160618  Degree:Doctor  Type:Dissertation  Country:China  Candidate:Z Q Li  Full Text:PDF  GTID:1108330479978605  Subject:Mechanical and electrical engineering  Abstract/Summary:  PDF Full Text Request  Table tennis requires its participants to be agile in decision and reaction. Based on these features, Tabletennis robot is regarded as an ideal benchmark for highspeed intelligent robot systems. In this dissertation, the kinematic control of redundant manipulators, visual tracking of the highspeed ball and learningbased batting decision are addressed using table tennis robot as the benchmark.A modified analytical inverse kinematic solution based on the arm angle parametrization method is proposed for the 7DOF anthropomorphic manipulators.The arm angle, which is defined as the dihedral angle between the arm and the reference plane, is adopted to describe the redundancy of the manipulators. Using this parametrization technique, the constraints of the redundant parameter imposed by joint limits can be represented as triangle inequalities that can be solved analytically. On each selfmotion manifold, the feasible arm angle interval can be obtained based on simple and easytoimplement trigonometric computation. Then valid joint configurations can be calculated for every arm angle in the feasible range. The validity of the proposed method is verified theoretically and experimentally in this dissertation. In addition, the forward kinematics is implemented based on MATLAB®symbolic computation. And the weighted leastnorm method is chosen as the differential inverse kinematic algorithm for the 7DOF manipulator after comparing stateoftheart differential inverse kinematic solutions.To deal with the motion blur of the highspeed ball, a stereovision based framework is presented: firstly the corresponding region of the ball is extracted using background subtraction. Then the blur parameters are identified by minimizing the L2 norm of the directional derivatives of the blurred image and the motiondeblurred image is obtained based on RichardsonLucy deconvolution. Lastly 3D location and velocity of the ball are reconstructed using RANSAC based circlefitting.This method can mitigate the motionblur effect greatly so that the visualtracking precision can be increased notably.Lastly, a method based on support vector regression is proposed to learn the batting policy. Table tennis playing is formalized as the batting evaluation function,which maps the state of the incoming ball and the parameters of the batting trajectory to the reward. This function is then obtained by generalizing the training data using?support vector regression. During online decision, the optimal batting trajectory is computed by maximizing the batting evaluation function with respect to the parameters of the batting trajectory. As this learning based method is modelfree, it makes the success rate of the batting free from unmodeled dynamics and parameter errors.The proposed methods are implemented on a 7DOF robotic tabletennis platform. And the experiments, namely the motion plan of the 7DOF manipulator, the visual tracking and the table tennis rallying verify their effectiveness.  Keywords/Search Tags:  tabletennis robot, 7DOF manipulator, analytical inverse kinematics, stereo vision, motion blur, batting decision, support vector regression  PDF Full Text Request  Related items 
 
