Analysis On Obstacle-climbing And Research On Control System For Wheel-legged Unmanned Ground Vehicle

Unmanned Ground Vehicle(UGV)has many advantages,such as high mobility and adaptability,strong obstacle crossing ability,and the ability to perform tasks in extreme environment and high intelligence.It is widely applied in military and civil field.The driving structures of unmanned ground vehicles are various,which are mainly divided into wheel type,leg type and wheel/leg type,caterpillar type,wheel/track type and wheel/track/leg type.Wheel-legged composite structure has not only high mobility of wheel type but also good obstacle-crossing performance of leg type.It has good adaptability to complex terrain and strong bearing capacity,and can accomplish specific tasks well,and that is why it has important research significance.But at present,the wheel-legged UGV is mostly rotary swing arm,which is controlled by installing a driving motor directly at the hinge point of the upper end of the swing arm.But the load at the hinge point is larger,and the power transmission route of wheel-legged UGV is longer,which make the power is easy to lose in the transmission process.There are still many problems in the bearing capacity,adaptability,load distribution and stability of wheelleg UGV etc.Based on the deficiency of wheel-leg composite structure and the important requirements of UGV in complex environment,and combined with the theoretical basis of UGV plane kinematics,steering kinematics,dynamics and mechanism,a new type of wheel-legged all-wheel-drive UGV with good obstacle crossing ability,mechanical transmission stability and good adaptability is proposed and developed in this paper.The swing arm of UGV is mobile swing arm with simple structure,and it has six wheels,six legs,and the left and right legs are symmetrical.The wheel-legs are designed by modularization and the front and rear wheel-legs can be exchanged.The swing arm is driven by the driving motor through the rack and gear.The hinged joint of the upper end of the wheel-legs can be moved and the load distribution is more reasonable.The parameters design,kinematics and dynamics analysis,control system design and wireless remote control of the pendulum arm mechanism of UGV are studied,which provides the basis and theoretical basis for the subsequent research of UGV motion controller design and autonomous navigation.The main research contents of this paper are as follows:(1)The overall mechanism design of UGV is carried out to meet the requirements of crossing obstacles of a certain height;the swing arm motor,motor abutment,driver,accumulator cell and control board are reasonably arranged in the vehicle frame,so that the quality of the vehicle is evenly distributed front and rear ends,and the corresponding motor and its components of reducer,driver and mechanical transmission parts are selected and assembled.The wheel-leg system is designed by modularization,which is convenient for disassembly,assembly and maintenance,and the wheel-leg system can be replaced with each other.(2)The force analysis model of UGV is established,and carried out plane kinematics and steering dynamics analysis,and derived its kinematics and dynamics equation.Aiming at crossing the typical obstacles such as vertical obstacles and trenches,the action planning in the process of obstacle surmounting is completed.With ADAMS software,it is carried out that simulation analysis of driving performance of straight driving on flat ground,passing through vertical barriers and trenches,steering and crossing the slope.The simulation results prove the correctness and feasibility of the structural design.At the same time,the simulation analysis of suspension system shows that UGV with suspension system can significantly buffer the impact from the ground and keep the stability of the frame.(3)The motor control system of UGV is designed,and the driving motor and swing arm motor can realize closed-loop servo control.The unmanned ground vehicle has six wheel-leg systems,and its motion system can coordinate with each other,and the realtime communication between driving units is accomplished.Speed servo control is used in driving motor and position servo control is used in swing arm motor.The control system design includes the motor control strategy design.(4)Based on the developed prototype,the UGV is debugged and tested,and the obstacle-crossing action of passing through vertical obstacles and trenches is experimented to verify the feasibility and correctness of obstacle-crossing action planning and its good adaptability to complex terrain.