The Motion Capacity Study of 7-degree-of-freedom Robotic Arm Using Product-of-exponential Method

Currently, most studies do not adequately discuss the selection of six-degree-of-freedom and seven-degree-of-freedom robotic arms and do not explore the differences between them. For investigating the advantages and disadvantages of six-degree-of-freedom robotic arm and seven-degree-of-freedom robotic arm in terms of range-of-motion ability and motion planning ability, this paper sets up a sphere-roll-sphere-type 7-degree-of-freedom robotic arm, establishes the model of this robotic arm through the product of the exponential method, and obtains its motion parameters. A three-dimensional simulation model of the robotic arm is ultimately created using Webots in Matlab. The Monte Carlo method was used to determine the workspace of the robotic arm and the results were innovatively utilised to compare the performance metrics of the six-degree-of-freedom and seven-degree-of-freedom robotic arms, including the range of motion and motion planning capabilities. It was found that the seven-degree-of-freedom arm, although not as wide a range of motion as the six-degree-of-freedom arm, could reach positions closer to the arm itself and has more precise motion planning capabilities. This result provides a reference point for people when designing robotic arm functions and number of degrees of freedom.