Dynamic Performance Of An Integrated Crawler Mobile Parallel Robot In Crossing Obstacle

To solve the problems of insufficient mobility of parallel robots,limited working space and low precision and stiffness of mobile manipulators in processing tasks,the mobile parallel robot is boosting.In this study,an innovative crawler mobile parallel robot is proposed.A virtual simulation model of the robot is established by using the flexible body finite segment model method.The strong nonlinear dynamic behavior of the robot during obstacle-crossing is analyzed systematically.The main contents are as follows:(1)The overall design scheme of the crawler mobile parallel robot was proposed,the overall structure of the robot was designed,and the static stiffness analysis and modal analysis of its parallel mechanism module were carried out.(2)A simplified model of the parallel mechanism module was established,its forward and inverse solutions were derived,and the finite discretization method was used to calculate the workspace of the robot.(3)By determining the motion law of the moving platform of the proposed robot,the motion path was designed,and the virtual simulation model of the parallel mechanism module was established.The results show that the position,velocity and acceleration curves of the moving platform are smooth and continuous,and the motion of the mechanism is steady.The experimental and the theoretical curve match well,the simulation model of the parallel module is correct and the trajectory planning is reasonable.(4)The crawler simulation model was established using the flexible body finite segment model method and the virtual prototype of the robot was constructed.The simulation analysis was carried out under three typical working conditions,namely,step,slope and gully.The results show that the maximum height of forward and backward climbing steps is 175 mm and 160 mm,the maximum climbing angle is 23°,and the maximum width of forward and backward crossing gullies is 465 mm and 615 mm,respectively.With the increase of step height,gully width and slope angle,the change range of the crawler slip rate increases and its fluctuation becomes more severe.The sliding phenomenon of the crawler becomes more serious,and the impact of the robot also is greater.Compared with the forward step climbing and forward crossing the gully,the reverse step climbing and reverse crossing gully movement is more stable and the impact is less.(5)Virtual prototypes of the robot with different swing arm lengths were established,and their movements in three typical conditions were explored.The results show that with the increase of the length of the swing arm,the robot’s forward step-climbing ability and forward gully-crossing ability will be improved,and both show a linear increasing trend,but the robot’s reverse step-climbing ability and slope-climbing ability will not be affected.When the length of the swing arm is less than 350 mm,the change of the swing arm length will not affect the ability of the robot to cross the gully in reverse,but the longer the swing arm,the more stable the robot’s movement.When the length of the swinging arm is greater than 350 mm,the longer the swinging arm,the stronger the ability of the robot to cross the gully in reverse.