Tham khảo tài liệu 'intech-climbing and walking robots towards new applications part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 360 Climbing Walking Robots Towards New Applications occurs due to excessive rotation of link 1 relative to the robot body. Not only to avoid this sticking condition and but also to maintain the design concept of passivity we suggested a limited pin joint at point P that restricts the excessive rotation of link 1 relative to the robot body as described in Fig. 1. The maximum allowable angle of link 1 relative to the robot body will be determined by the kinetic analysis in the next section. a b Fig. 3. Sticking Conditions 3. Kinetic Analysis In this section we introduce the detailed analysis of the WMR s states while the WMR with the proposed passive linkage-type locomotive mechanism climbs up the stair. The states are classified in the position of the point and the status of contact between the driving wheels and the stair. The kinetics and the dynamics of the proposed locomotive mechanism at each state are also different from each other due to the posture of the WMR and the contact forces on the driving wheels at the points of contact. The reasons for classifying the climbing motion of the WMR into the several states are to describe the contact forces acting on the driving wheels as the analytic functions and analyze the kinetics of the proposed WMR. For the whole states the contact forces can not be expressed in the analytic function due to the absence of contact on certain driving wheels. For each state however the normal forces and the corresponding friction forces acting on the driving wheels can be described in the analytic functions. From the kinetic analysis of each state the geometric constraints to prevent the WMR from falling into the sticking conditions are suggested and the object functions to improve the WMR s capability to climb up stairs are derived. The design variables of the proposed WMR are shown in Fig. 4. Link 2 Body L L7 L2 L8 Link 1 Wheel 3 MW2g Fig. 4. Design variables of the WMR with the proposed mechanism Link 3 Wheel 2 IT d .
