Performance Analysis Of Joint And Study Of Extended Locomotion For Snake-Like Rescue Robots

Snake-like rescue robots with multiple locomotion modes have broad application prospects in the rescue task because of its better terrain adaptability than the crawler, legged, flying rescue robots. The joint mechanism and locomotion modes have been hotspots and difficulties in snake-like robots research work. However, current study of joint performance only remains in mobility and working space. And research on locomotion modes focusses on stability while ignoring the mobility. In view of no depth study of joint performance and lack of mobility of locomotion problems, this paper takes a snake-like rescue robot with bionic parallel joint mechanism and orthogonal active wheels as the researching object, and does some research on joint performance and locomotion modes in detail. The main contents are as follows:1?Starting from motion mechanism of the snake, a bionic parallel joint mechanism (BPJM) designed for snake-like robot is studied with circumstances. The bionics principle of the BPJM is illustrated through screw and reciprocal screw theory. With the aid of screw algebraic structure, dynamics equations for moving platform and links are formulated by Newton-Euler approach. By analyzing the simulation results, the force at joints and acting on links are studied.2. In view of lower-mobility of the BPJM and the deformation of branch chains, the dexterity and static stiffness distribution of BPJM inside its reachable work space is researched. The dexterity index of BPJM is constructed with the condition number of driving jacobian matrix. The stiffness model of the BPJM is established by considering both bending deformation existed in the constraint chain and elastic deformation in driving chains. Followed linear and rotational stiffness distribution is investigated.3?Aiming at the problem that serpentine locomotion's efficiency is low in the environment containing slope and cylinder terrain, new locomotion mode is extended for the snake-like robot by combining orthogonal active wheel's mobility and bionic parallel joint's self-locking characteristic. Dynamic model for snake-like robot is formulated based on screw theory. By analyzing the motion constraint properties of turning and climbing locomotion, simplified dynamic model suitable for the control is established.