| The mobile platform of rescue robot has an important impact on the performance.At the same time,the mobile robot can be used not only for the rescue.It also be used in military,space exploration and other fields.Thus the mobile robot has a wide application prospect.This paper presents a wheel-legged mobile robot with 3-PUU parallel structure.The stability,gait,kinematics,trajectory planning of the robot are studied.First of all,the 3-PUU parallel structure is used as the main structure of the mobile robot.The limbs of the parallel mechanism are used as the legs of the mobile robot.The omnidirectional wheel is used as the wheeled structure of the mobile robot,so that the mobile robot can move in all directions.The prismatic pairs are used to realize the mutual conversion between the wheel movement and the leg movement of the robot.Secondly,the kinematics of the robot is analyzed according to the kinematic characteristics of the mobile robot.The velocity of mobile robot is effected by three resultant velocity produced by three omnidirectional wheels and axles.Then the relationship between the velocity of robot and the velocity of omnidirectional wheel is solved according to the characteristic.The kinematics analysis of the main body of leg structure of the robot is carried out.The kinematic equations and the Jacobian matrix of the mechanism are solved.The singularity configuration are analyzed.According to the kinematics analysis of the 3-PUU parallel mechanism,the proper mechanism parameters are selected.Finally the motion space of the mechanism is drawn out.Then,the stable state of the mobile robot is divided into static stability and dynamic stability according to the force state of the robot in the moving process.According to the mechanism characteristics of the 3-PUU wheel-legged mobile robot,a walking mode suitable for the mobile robot is proposed.Then using the method of center of gravity and ZMP the analyses of robot stability are carried.The swinging motion of the legs and the forward movement of the hip are realized by the mutual conversion of the moving platform and the static platform.In the whole robot structure,the alternately of swinging legs and supporting legs of the two groups are realized by sharing the same platform to realize the advance of the whole robot.Then the turning and moving mode of the wheeled structure are stipulated.Finally,according to the characteristics of leg movement of the mobile robot and the motion characteristics of the mechanism,the cubic spline interpolation method is used to plan the trajectory of the robot,so that the mobile robot does not have any impact in its movement progress.The variation of prismatic pair is obtained using the MATLAB programming based on the inverse solution formula of the mechanism. |
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