Trajectory Planning And Working Characteristic Analysis Of C-shaped Gantry Five-axis Linkage Hybrid Machine Tool

In this paper,a five-axis machine tool consisting of a Three-Translational C-shaped gantry parallel machine tool and a C-A tool is taken as the research object.The key technologies such as kinematics analysis,trajectory interpolation,speed control and redundant slider position planning of the machine tool are mainly studied.The main work of this paper is as follows:First,the kinematics of the machine tool were studied.Based on the structural characteristics and kinematic relationship of the five-axis hybrid machine tool,the inverse position equation,position expression,inverse matrix of speed Jacobian matrix,and acceleration mapping of the parallel mechanism are deduced.Briefly explained that the positive solution equation has multiple position solutions of mechanism and the method of determining position solutionsSecondly,according to the motion relationship of machine tools,a two-step interpolation strategy is proposed.In order to solve the non-linear error problem caused by the original linear interpolation calculation of the C-A tool rotation angle,the tool orientation interpolation algorithm is used in Cartesian space.Then,the characteristics of telescopic rod length curve fitted by linear interpolation algorithm,cubic B-spline interpolation algorithm and PVT interpolation algorithm are compared and analyzed.The simulation results show that the rod length curve obtained by the PVT interpolation algorithm is smooth.The velocity and acceleration curves are continuous in a single cycle.And the length error is small.Then,according to the two-step interpolation strategy and motion characteristics of the machine tool,a speed control strategy combining the linear acceleration algorithm and PVT interpolation algorithm of the hybrid machine tool is proposed.This paper analyzes the phenomenon of machine tool overshoot and speed oscillation when the speed control strategy is implemented using common linear acceleration rules.And a recursive algorithm is proposed to solve the above problems.Experiments on different linear acceleration processes prove that the above method can obtain higher trajectory accuracy.The calculated actual speed curve and the theoretical speed curve almost completely coincide,and the actual speed curve is smoother.Finally,the relationship between the position of the redundant slides of the machine tool and the dexterity distribution of the parallel mechanism is analyzed.Therefore,the dexterity criterion is used to plan and select the position of the redundant slider,and the motion of the machine tool is simulated based on this method.Then,after the redundant sliders are planned,the stiffness distribution of the mechanism is analyzed through the established stiffness analysis model.The position of the worst stiffness performance in the workspace was searched,and this position can meet the processing requirements,which proved the effectiveness of the planning method.