| As an intelligent unmanned platform that can replace operators to perform rescue and detection tasks in the complex terrain environment of disastrous scenarios,mobile robots have very important application value.Wheeled mobile robots is widely used in dangerous operations because of its high energy efficiency and simple structure and control.However,wheeled mobile robot has some mobility problems in complex terrain,such as low terrain adaptability and poor obstacle-crossing ability.To solve these problems,this paper presents a novel portable six-wheeled mobile robot with a reconfigurable body and self-adaptable obstacle-climbing mechanisms,which can reconfigurable itself to three locomotion states to realize the advantages of terrain adaptability,obstacle crossing ability and portability.It has a wide application prospect in disaster rescue,mine clearance and explosive disposal detection.Around the proposed mobile robot,the main work and innovations of this paper include the following aspects:(1)Aiming at the mobility problem of wheeled,a new reconfigurable wheeled robot is proposed.Design criteria and overall design idea of the proposed mobile robot are firstly presented firstly,based on which the mechanical structure design of the robot is completed.The robot has a unique three-rocker-arm structure to ensure its adaptability to complex terrain,and improve its obstacle crossing ability by reconfiguring itself through the Sarrus-variant mechanism.(2)The working principle of the adaptive matching of the robot with the terrain through the three-rocker-arm suspension structure is described.The geometric parameter model of the robot is established,and the centroid kinematics model and ground wheel contact static calculation model of the robot is established on this basis.Taking crossing an isosceles right triangle obstacle as an example,the smoothness of the robot’s motion and the homogenization characteristics of the ground wheel contact force are analyzed through numerical simulation.(3)The principle of the robot’s climbing over the obstacle adaptively by turning the adaptive climbing rocker arms is described.The geometric passing capability,static conditions and motion stability conditions for obstacle crossing of the robot are derived.Through numerical simulation,the geometric passing capability,static passing capability and motion stability for obstacle crossing are verified,and the feasible region of the geometric configuration that the robot can cross obstacles is obtained.(4)The robot’s reconfiguration principle based on Sarrus mechanism is expounded,the kinematic and static models of the robot reconfiguration are established,and the relationship between the output torque and speed of each motor in the process of reconfiguration is obtained through numerical simulation.The dynamic control of the robot reconfiguration is realized.(5)According to the mechanical design of the robot,a physical prototype of the proposed mobile robot is developed and integrated with mechatronic systems and remote control.Using the prototype,field experiments are carried out to verify the feasibility of the proposed design and theoretical derivations.The experiments show that the robot satisfies the design criteria such as terrain adaptability,obstacle crossing ability and portability.An adaptive obstacle crossing algorithm is proposed,which enables the robot to climb over the obstacle without sensing the height the size of the obstacle. |
