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Control of Redundant Robot Manipulators - R.V. Patel and F. Shadpey Part 6

Tham khảo tài liệu 'control of redundant robot manipulators - r.v. patel and f. shadpey part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 66 3 Collision Avoidance for a 7-DOF Redundant Manipulator time s c Figure 3.17 contd. Simulation results for MOCA with fixed weighting factors c 2-norm of joint accelerations rad s2 The optimal value of WC depends on factors such as object velocity end-effector velocity and location of the critical point. Therefore from preliminary simulations it was observed that finding a fixed value which performs well in different situations is very difficult. To overcome this problem a time-varying formulation 14 has been used to adjust the weighting factor automatically. In this way the weighting factor corresponding to each active task is adjusted according to the following scheme f 1 1 Wc dc-RoỲ SOI-Ro-V 33 16 where dc is the distance between the critical point on the link and either the center of the object for a spherical object or the projection of the critical point on the axis of the cylinder in the case of a cylindrical object. RO and SOI are the radius and surface of the influence of the object respectively. shows the results of the simulation using this formulation which for the case of k 0.01 shows successful operation of MOCA with minimum acceleration. 3.3 Kinematic Simulation for a 7-DOF Redundant Manipulator 67 ----k 100 k 1 -.-.- k 0.01 obstacle s radius 70 mm and SOI 100 mm time s 2-Norm of the Joint Velocities 0.45- 0.4- 0.35- 0.3- 0.25- 0.2- 0.15- 0.1 - 0.05 00 0 .5 1 1 .5 2 2.5 3 3 time s b .5 4 Figure 3.18 MOCA simulation results for time-varying weight factors a critical distance mm b 2-norm of joint velocities rad s 68 3 Collision Avoidance for a 7-DOF Redundant Manipulator ox 103 31---1------1-----1----1----1-----1-----1---- 2.5- - 2-1 - W 1.5- I - 1 ị - 0.5- - I 00 0.5 1 1.5 2 2.5 3 3.5 4 time s c 0 0.5 1 1.5 2 2.5 3 3.5 4 d time s Figure 3.18 contd. MOCA simulation results for time-varying weight factors c Wc d 2-norm of joint accelerations rad s2