Research On Ground Obstacle Avoidance System Of Unmanned Powered Parachute Based On Lidar

Unmanned powered parachute vehicle（UPPV）has been developed from parafoil,which is widely used in aviation,war,and rescue and relief.As an unmanned control system,the autonomous obstacle avoidance ability of UPPV needs to be further improved.In this paper,the obstacle avoidance system of UPPV on the ground was studied,and the existing obstacle avoidance algorithm was improved.2D lidar was selected as the sensor of obstacle avoidance in UPPV,the obstacle avoidance platform was designed and built,and the obstacle avoidance test was carried out.The main work of this paper is as follows:Firstly,the coordinate system,odometer model and kinematics model of UPPV were established,and the grid map was selected as the description method of the environment map.The Simultaneous Localization and Mapping（SLAM）of UPPV was studied to solve the positioning problem of UPPV.Secondly,the obstacle avoidance algorithm of UPPV was studied.In view of the defects of Dynamic Window Approach（DWA）algorithm in obstacle avoidance application,the paper proposed an improved DWA（IDWA）algorithm to obtain the optimal execution speed with better azimuth range constraint.That is,after the trajectory simulation was completed,the trajectory within the optimal azimuth range was selected and evaluated to obtain the execution speed corresponding to the optimal trajectory.The MATLAB software was used to simulate the obstacle avoidance processes of DWA and IDWA algorithms in different environments.The simulation results showed that IDWA could make the UPPV pass through the dense area of obstacles,avoid long-distance detour and improve the operation efficiency.Finally,taking the robot operating system as the development platform,the ground obstacle avoidance system of UPPV was designed,including hardware system and software system.The stability of obstacle avoidance system was verified on the established obstacle avoidance platform of UPPV.The obstacle environment was set up and the obstacle avoidance experiments of A*-DWA algorithm and A*-IDWA algorithm were carried out respectively.The test results showed that the obstacle avoidance test scheme of A*-IDWA algorithm could not only make the UPPV run stably among obstacles,but also shorten the obstacle avoidance time obviously.