Throwing Robot Flippling Obstacle Negotiation Technology Research

Throwing robots are small in dimensions and light in weight, and they can be deployed into complex, narrow and dangerous areas by throwing, ejecting and air-dropping methods. But these robots can only move in small squares, and their obstacle-overcoming ability is poor, especially in urban environment, the common steps and stairs can be the obstacles they cannot overcome.This paper is carried out base on the background of XX Project, focusing on researching a throwing robot with flipping ability. This robot can be used to solve the contradiction between robot’s dimension, weight and obstacle-overcoming ability. A new structure scheme is put forward, adding rotate arms to a common wheeled chassis, and by that structure the robot can flip continuously to overcome stacles. Kinetic and dynamic researches have been deployed around this scheme, and a prototype has been developed. Some anti-impact research has been done based on this prototype, aiming to meet the throwing demand. The throwing robots mobile range can be expand by this research, and this has important meaning for reconnaissance in short distance. The researches are as follows in detail:The classical small obstacle-overcoming structures are summarized, and a new movement principle and structure scheme of chassis flipping is put forward, with the goal of little dimension and high obstacle-overcoming ability. Rotate arm components are designed based on a small wheeled chassis, and the arms can rotate around the center of chassis. When the arm’s ends stick on the ground of step surface, the chassis’ gravity center will be lift up by the force from ground. The arms continue rotate when the chassis posture is vertical, and the chassis will fall forward, that is the flip progress. The robot can realize the function of climbing stairs by chassis’ flip movement. The structure and control system were designed around this scheme, and a prototype is developed.The kinetic and dynamic models were established to analysis the dynamic characters in moving forward, hill climbing and turning process. The whole progress of climbing one step was divided into eight states, kinetic functions were established to describe every state. The critical dimension requirements are analyzed based on the kinetic model, the relationship between robot’s dimension and step’s height that robot can climb up was pointed out. Force analysis work was done based on classical states, and the stability was analyzed further more.A virtual prototype is established based on dynamic soft RecurDyn and its control modular Colink. The virtual prototype’s structure system contains mass, moment of inertia, friction force and other information, and control system contains kinetic model and rotor model. By this virtual prototype, authors did stair-climbing simulation to confirm the new scheme’s feasibility preliminarily. Accelerating, turning, hill climbing simulations have been done to predict the max velocity, max climbing angle, driving torque in turning process and other characters.Anti-dropping capability is an important character for throwing robots. The initial prototype is analyzed based on the nonlinear software ABAQUS. According to the materials used by the prototype, 3-order Odgen Model was used to describe super-elastic material rubber, and Johnson-Cook Model was used to describe the elastic-plastic material metals. Four focuses and the evaluation criteria were put forward. Three classic posture dropping process were simulated for the initial prototype, and some weak parts and problems were pointed out. Based on the analysis results, four measures were developed, containing wheel structure, material and structure of shell and wheel axle, the link method between motor and wheel axle and wheel axle protect structure. Some compact simulations were done to confirm the effectiveness of optimizing measures. The result showed that the strength and stiffness were improved significantly, and the robot can resist on dropping impact of 5m height.Various kinds of stair-climbing experiments were done to test the capability of the principle prototype. The results show that the new kind of movement scheme is feasible, and the critical dimensions of this robot are reasonable, the robot has a wide range of adaptability for stairs. Routine experiments were done to test its movement performance and environment adaptability, such as moving forward, hill climbing, driving on grassland, gravel land, sandy land and ruin areas. Some of those experiments confirm the accuracy of theory model and virtual prototype. 1m dropping experiments of three typical postures have been done, the results confirm the accuracy of simulation model.