Study On A Small Special Ground Mobile Robot Coupling Wheel And Track

Wheel/track coupling type is a new type of mobile combination,compared with the traditional Wheel/track multiple robots,it only has one set of walking mechanisms,so the structure is simple and compact,and it can easily switch between wheel mode and track model,and it both has the wheel's energy saving and the characteristics of the crawler-type's high obstacle crossing.This combination is especially suitable for urbanization terrain,where most flat ground but ocasional obstacle of steps.Wheel mode is for the flat ground and the caterpillar can be used to climb the steps.With the progress of the global urbanization,wheel/shoe coupling type robot will play more and more important role.It can be applied in the patrolled surface searching and rescuing,planetary exploration,investigation,anti-terrorism riot,wheel-chair occasions and so on.Many scholars have been reserching the wheel-track coupling type,but at present there is no a complete theory system theory about this type robot,most of them stay on the engineering experience.In view of the practical significance of the wheel/track coupling mechanism and the lack of relevant theoretical system,whth the help of two kinds of small wheel-track prototype,this paper is a research aobot entire structure design,the structure of retractable track and model of track-gornd interaction,obstacle-crossing modes selection rules and planning of each obstacle-crossing mode,considering the influence of typical load 6-DOF arm's influence on the wheel's robot's obstacle-crossing ability,and the trajectory tracking control considering both horizontal and vertical sliding factors.This paper first introduced the overall structure of the small wheel-track coupling mobile robot,mainly including walking wheels,transforming device,tail,and box.Transforms devices are installed inside the wheel,and the walking wheel is different from the ordinary.It needs to been divided into two sheets,which need a separate location and synchronous drive,otherwise it will interfere with the transforming devices when the robots walks in track mode.For walking wheel device,this paper puts forward a positioning method based on the internal gear ring of the bearing unit,integrated driving wheel,shaft drive and so on.The several schemes are compared with their advantages and disadvantages and applicable occasions.For transforming device,this paper puts forward the design method of double four-bar linkage and a screw driver design method.Through analysis of the tail rod's action and in order to improve the ability of the obstacle-surmounting performance,this paper presents a unidirectional tail rod mechanism,and applies 360 ° turnover tail rod on this type robot.Walking wheel device and transforming device decide the form of the box,mainly considering whether the driving motors are installed in box.Retractable track is the most component of the wheel-track couping robot.In this paper,after analysing the retractable track based on deflection coefficient method and no-tooth track,the method of using simple synchronous is put forward.The wheel/track coupling robot also can work under sand,clay and soft ground in the actual work,so wheel/track-ground interaction model is established to analyze the tracktion and the influcen of the track's structural parameters.The obstacle-surmounting performance is an important function of wheel/track robot.The obstacle-surmounting performance is not only influenced by wheel size and transforming mechanism parameters,but also the length of the body and tail rod parameters.Wheel/track robot has a variety of obstacle crossing models,when faced with different heights of the steps obstacle,robots need reasonable mode to surmount obstacles to go through.This paper analyze such as the limit obstacle-corossing heights of differents modes such as wheel,track,wheel-tai,track-tail and so on,and makes the robot obstacle-crossing mode selection strategy and the planning.6-DOF arm is the most typical load for mobile robot,static and dynamic characteristics of other load can be equal to it.So this article analyzes 6-DOF arm's impact on the robot's obstacle-crossing performance.Traditional wheel/robot modeling is not considering the influence of the parameters of sliding,but these sliding parameters has great influence in the autonomous trajectory tracking of robot.Based on the traditional wheeled and tracked robots kinematics modeling,the robot's dynamic model is established including the effect of sliding factors.This paper introduces the method of SR-EFK to estimate the sliding parameters.Because the dynamic model need consider the influence of too many factors,so based on the kinematics model,a kind of adaptive controller is established with sliding parameters,the simulation results show that the robot in the adaptive controller can overcome the effects of slip effect.Finally,experiments are carried out to prove the prototype's parameters meeting the requirements of the subject index such as speed,climbing steps and stairs and so on.The feasibility of the robot's strucutre,walking device,transfroming device,retractable track are validated in the experiments.sts The robot can crosst several complex flat terrain and can choose feasible obstacle-crossing mdoe to succeeding crossing different heights steps show the feasibility of the mode chosing rules and each planning method.