Abstract: The test rig of the A-frame which is used more at home and abroad is carried out kinematic analysis. The offsets of slip angle, camber angle and the tire trace center are discovered when the test rig is in the composite posture of slip angle and camber angle. The offset formula is deduced by the method of space analytic geometry based on the tire coordinate system defined in ISO. The results showed that each offset can’t be ignored in a large complex attitude angle. In order to effectively solve the phenomenon, a novel structure of six degrees of freedom(DOF) tire test rig is proposed. The length of six electric cylinders is calculated when the new test rig is in different postures by the Euler angles of rotation method. The control precision of attitude angle of the tire is analyzed and six DOF platform electric cylinders are space rearranged. The results showed that each physical quantity is with no offset when the new structure six DOF tire test rig is in the composite posture and the tire posture can be arbitrarily controlled. As the same time, a new program of six power cylinder arrangement improves the control precision of tire attitude angle.

Key words: Control precision, Kinematic analysis, Six degress of freedom tire test rig, Tire attitude angle, Tire test rig