Tham khảo tài liệu 'mobile robots book 2011 part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 316 Mobile Robots - State of the Art in Land Sea Air and Collaborative Missions Sets of end effector orientation in the workspace cd CM f Q -Q cc w CD 0 600- 400- 200- 00 50 100 150 200 250 300 350 400 450 500 800- 600- 400 600- 400- 200- 1000r T1 T2 50 100 150 200 250 300 350 400 450 500 T3 50 100 150 200 250 300 350 400 450 500 500 - T4 00 50 100 150 200 250 300 350 400 450 500 Fig. 3. Static cable forces at different end effector orientations 5. Design Criteria of the Ankle Rehabilitation Robot In light of the unidirectional nature of cable forces design of the proposed cable-based manipulator is more complicated than the rigid-link parallel robots. There are certain criteria specific to the cable based parallel robots which require more attention. These design criteria are discussed below 1. Maximum workspace criterion 2. Near unity condition number criterion 3. Singular value based criterion 4. Minimum force norm based criterion 5. Other criteria An explanation of these measures is important to state their significance. Workspace Criterion Workspace is a vital parameter in the domain of kinematic analysis and workspace analysis of the proposed robot is discussed in section . The feasible workspace volume depends on the geometrical configuration of the robot such as the size of the platforms and placement of connection points on them apart from other constraints discussed in the previous section. Thus by changing the geometrical parameters it is possible to change the volume of the feasible workspace. It is desired that the workspace of a robot under given constraints should be as large as possible for greater maneuverability. Furthermore unlike serial robots workspace of parallel robots is unevenly shaped Stump and Kumar 2006 due to their complex kinematics. This further contributes in lowering the size of the feasible workspace. Apart from the size the quality of the workspace is also important and it is desired that the Multi-criteria Optimal Design .