An On-Line Tool Path Smoothing Algorithm for 6R Robot Manipulator with Geometric and Dynamic Constraints

The tool path smoothness of the industrial robot directly influences the dynamic performance of its motion control. Therefore, it is important to smooth the path that is composed of small linear segments, in order to achieve continuous and smooth movement. This paper uses the FIR filter interpolation method to generate the smooth tool tip position and tool orientation trajectory for robot manipulators with 6 rotational (6R) joints. The geometric smoothness and motion interpolation are achieved in one step. The maximum velocity and acceleration of joints are constrained when calculating the time parameters of the FIR filter. By specially designing the overlapping time at transition corners, the tool tip position and tool orientation deviations are all constrained in the workpiece coordinate system. Considering the complexity of the inverse kinematics of the robot, in order to constrain the velocity and acceleration of robot joints, this paper proposes a simplified method which directly establishes the relationship between joint motion and tool motion through the derivative of joint motion to tool motion without considering the inverse kinematics. Simulation and experiment results show that the algorithm can generate continuous acceleration commands of the tool tip position and tool orientation within the corner error tolerance. The preset velocity and acceleration limitations of six joints are all constrained well. Comparisons with existing algorithms demonstrate advantages of the proposed method.