Design And Mobility Analysis Of A Multi-Mode Two-Wheel Mobile Robot

In order to realize the remote control,autonomous working,it's important for the small-scale ground mobile robots to be in small size and small mass for easy carrying,and to have strong obstacle-crossing ability in complex terrain conditions and flexible deformability in a variety of workspaces.It is difficult for current small-scale ground robots to meet these three points at the same time because of the limit of dimension.After the research of obstacle-crossing technology for small-scale robots,combined with the concept of the overall deformable mechanism,this paper proposes a novel multi-mode two-wheel mobile robot with deformable chassis,and the analysis for obstacle-crossing in convex polygon of deformable single-loop closed-chain mechanism is developed.First of all,the concept of a multi-mode two-wheel mobile robot is explained.On the base of planar 6R single-loop closed-chain link mechanism,the deformable chassis is designed.Through its deformation,four modes can be obtained:the deployable mode,the two-wheel mode,the rolling-track mode,and the obstacle-crossing mode.In the deployable mode,it can be used for storage and transportation in the folded state,and starts the working mode when it's unfolded.In the two-wheel mode,the deformation of the chassis can adjust its form to change its turning radius and body width to increase its terrain adaptability.In the rolling-track mode,rolling is realized via the alternate touch of each link on the ground,which increases the area of contact with the ground so as to achieve rolling on uneven or soft road surface.In the obstacle-crossing mode,the chassis can be deformed into convex polygon to enhance the climbing effect on the obstacle,which make it possible to climb the high step and the stairs.A general kinematics model for all modes is established for the analysis of all the movement,including the kinematics and dynamics of the two-wheel,the rolling track,and the obstacle-crossing mode.Particularly,gait of convex deformation for chassis is planned for the obstacle-crossing process,then a detailed mechanical and torque analysis of key gaits is carried out,and the key motion constraints and mechanism dimensions are obtained.A virtual prototype is built in Adams software to conduct the dynamic simulation.A prototype based on the theoretical analysis is manufactured to verify the feasibility of the multi-mode robot and the correctness of the analysis.For conclusion,this paper proposes a novel multi-mode mobile robot with a simple and light structure,which has multi-terrain adaptability and large deformability.The theoretical modeling calculation,simulation analysis and prototype experiment are carried out to prove the feasibility of the robot.This provides new research ideas and analysis methods for improving the obstacle-crossing ability of small-scale ground mobile robots.