THE FORMATION OF THE BANK OF GAITS FOR A CRAWLING SEARCH ROBOT WITH CONTROLLABLE FRICTION IN BEARING SUPPORTS

The paper considers a three-link crawling snake-like robot, the links of which are connected by two-axis hinges. The robot is equipped with four bearing supports with the controlled coefficient of friction between them and the surface. The device is designed to move inside buildings after the emergencies to search for people under the debris and to transport the essentials to them. The robot is controlled by the operator in two modes: the sequential execution of commands (forward, backward, turn, etc.) and moving from the starting point to the final one. Working in each of the control modes requires the use of the gaits bank. The authors developed the classification of gaits for a crawling robot based on several criteria: the admissible periodic separation of links from a surface, the ability to control by friction in the supports, the combinations of controllable bearing supports, and the implemented type of motion. The authors studied in detail the controllable planar gaits of a robot when moving it forward and distinguished four types of gaits: longitudinal, transverse, transverse s-shaped, and longitudinal-transverse. For each gait the sequence of stages is developed, the conditions of their beginning and end imposed on the movements of the links are formulated and the vector of generalized coordinates is defined. As a result of numerical simulation, the authors built the graphs of trajectories of the centers of mass of links and the center of mass of the entire device for each gait, as well as the graphs of time dependences of the angles of rotation of links. The study identified the influence of angles of links relative positions on the distance traveled by the robot. It is revealed that for the same time of movement, the robot will pass the greatest distance with a longitudinal gait irrespective of angles of links relative position. The device will be able to march the same distance at two types of transverse gaits at the maximum possible angle of the links relative position.