The Structure Design Of A Quadruped Robot With Rolling Mode And Research For The Motion Planning

Mobile robot is the product of progress in science and technology. It represents the topachievements of mechanical and electrical integration, and is one of the most active fields inthe development of science and technology. Mobile robot comprehensive mobility aredetermined by moving mechanism which is the key for quickness, stability, accuracy andefficient mobility that can be realized in the work environment. Mobile robot is required tohave multiple locomotion modes because of the multi-featured working environment.Therefore, the mobile mechanism which has several mobile modes is become the hotspot inthe research, and using a set of institutions to realize two modes is efficient.According to theview of body bionics, a quadruped robot with rolling mode is put forward based on thesummary of the latest research results at home and abroad. This quadruped robot has twomove modes: walking mode and rolling mode, and the purpose can be achieved by theindependent conversion between the two modes. The quadruped robot whith rolling modelcan be transited automatically from walking mode to close chain rolling mode by the joints’transformation. During the rolling mode, the rolling movement is driven by the gravitationaltorque of the centroid offset that is cause by the structure configuration adjusting movement.Firstly, the bow-shaped-bar and spherical cap structure are introduced into quadrupedrobot, and the structure is designed based on the symmetry theory. The four limbs ofquadruped is composted by bow-shaped- bar, and the body shape is the spherical cap; thespherical cap body and bow-shaped-bar have the same curvature; hip joint with two degreesof freedom, knee and ankle joints each with one degree of freedom; mass center distributionand the structure parameters of limbs and trunk are designed according to rotational symmetryprinciple.Secondly, the quadruped robot is simplified as a planar six-bar mechanism in the processof transition from standing posture to the rolling mode. kinematic model of the centroid of thetransition process is established. The mobile strategy for Centroid is Put forward; theterminate robot configuration is optimized through penalty function. According to thenonlinear characteristics of the kinematic equations, joint trajectory is planed by least squaremethod based on the principle of minimum energy.Once more, the rolling mode of robot is simplified as closed chain five-bar linkagewhen rolling on the flat surface. the segmentation functions are used to derivate the kinematicconstraint equations and the center of mass trajectory equations during a rolling cycle, as wellas the center of mass motionvelocity and acceleration equations.Finally, based on the summary of the deficiencies in the existing rolling institutionaltrajectory planning, the constant center of mass offset joint trajectory planning strategy isput forward, as well as the premise conditions of smooth motion and joint continuity. jointtrajectory are planed in a rolling cycle according to this strategy. The planning results verify the correctness and rationality of the trajectory planning strategy, and also verify thesuperiority of the quadruped robot on the structure.