TAILIEUCHUNG - Parallel Manipulators New Developments Part 9

Tham khảo tài liệu 'parallel manipulators new developments part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Calibration of . Translational Parallel Manipulators Using Leg Observations 231 For the Zero posture the differential relations are derived in the neighbourhood of the point p0 0 0 0 po L L L which after substitution to 5 gives the Jacobian matrix 1 0 0 -1 0 0 J 0 0 1 0 0 -1 0 . 0 0 1 0 0 -1 6 Hence in this case the TCP displacement is related to the joint offsets and the leg lengths variations ALi by trivial equations APi V - - ỵL i e x y z 7 For the XMax posture the Jacobian is computed in the neighbourhood of the point p LSa 0 0 p L LSa LCa LCa where a is the angle between the y- z-legs and the X-axes a asin Pmax L Sa sin a Ca cos a . This gives the Jacobian J X 1 0 0 1 0 0 T L a 1 0 - Ta - C a 0 T a 0 1 - Ta 0 - C 8 where Ta tan a . Hence the differential equations for the TCP displacement may be written as Apx y. - ALx Ap Ta Apx An - TaXLx - Cax L y L V t x t y L v x L v y Apz Ta APx Apz - TaXLx - CaỴ AL 9 It can be proved that similar results are valid for the YMax and ZMax postures differing by the indices only and also for the XMin YMin ZMin postures. In the latter case the angle a should be computed as a asin pmin L . 3. Calibration method Measurement technique To identify the Orthoglide kinematic parameters specified in the previous section two approaches can be used which employ different measurement techniques to evaluate the leg-to-surface parallelism. The first of them Fig. 4a assumes two measurements for the same leg posture to assess distances from both leg ends to the base surface . The second technique Fig. 4b assumes a fixed location of the measuring device but two distinct leg postures which are assumed to be parallel to each other in the nominal case. It is obvious that for the perfectly calibrated manipulator both methods give zero differences for each measurement pair. In contrasts the non-zero differences contain source information for the parameter identification. However the first method involves absolute measurements that .

TỪ KHÓA LIÊN QUAN
TÀI LIỆU MỚI ĐĂNG
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.