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Mobile Robots -Towards New Applications 2008 Part 4

Tham khảo tài liệu 'mobile robots -towards new applications 2008 part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Robotic Grasping A Generic Neural Network Architecture 111 selected in increasing order of the predicted error. The procedure described in step 1 is repeated until a satisfactory solution is found or until all the experts are tested 3. If no satisfactory solution is obtained during steps 1 and 2 an expert is randomly chosen and a reaching motion is constructed from the fingertip position derived from the expert representative posture to the desired fingertip position. This procedure is repeated until a solution is found or all the experts are tested 4. If no solution is obtained during steps 1 2 and 3 a posture is randomly computed and a reaching motion is performed between the actual and desired fingertip position. This procedure is repeated until a satisfactory motion is generated i.e. no singular position and joints within their limits . If so the finger configuration obtained at the end of the reaching motion is considered as the representative posture of a new expert which is added to the set of experts. 3.2 Reaching motion and iterative improvement of fingertip position In this section the reaching motion definition and the iterative improvement of fingertip position Oyama Tachi 1999 Oyama Tachi 2000 are described. We consider 0 0 the output of one selected expert. Then the error between the current and the desired fingertip position is computed e 0 Xd - g 0 0 4 Xd represents the desired fingertip position and g . the finger forward kinematics. Two cases are considered 1. if e 0 rst rst being a predefined threshold perform the iterative procedure is performed and the joint angles Q k 1 are computed according to the following equation 0 k 1 0 k r 0 k XD - g 0 k until e k re 5 re is a second predefined threshold. 2. if e 0 rst a reaching motion is performed. To do this a straight line is constructed in Cartesian space from XC g 0 0 to Xd according to the following precdure Let T be an integer satisfying the following inequality T _1 lA M T 6 r. 1 st The .