The Mixed Research For Force/Position Of A Planar Four-legs Redundantly Actuated Parallel Mechanism

Parallel mechanism has been widely used in the industrial field with its compact structure, high positioning accuracy, big rigidity, good symmetry properties and strong carrying capacity and other advantages, for example, aircraft simulators, micro-manipulator, force and torque sensors and parallel Machine Tools and so on. However, compared with serial mechanism, parallel mechanisms have some obvious disadvantages due to structural limitations such as smaller work space, hard to be calibrated and singularity. The robot will be a total loss of rigidity and become unable to control when it is in a singular Configuration. At the same time as a result of the existence of singularity, the small work space of parallel mechanism will become smaller. The introduction of redundancy will help to improve the characteristics of parallel mechanism, thus reduce or completely eliminate the singularity Configuration of work space, and optimize the assignment of driving force and the reasonable distribution. Therefore redundant parallel mechanism has now become a focus for the current research.This paper mainly studys the Plane 2-dof redundantly actuated parallel mechanism. First of all, it carries out parallel kinematics analysis for the Plane 2-dof redundantly actuated parallel mechanism, including the inverse kinematics solution, positive solution, the solving to the Velocity Jacobian Matrix, and based on this, the simulation experiment of trajectory planning can be conducted.Secondly, this paper takes the GT-400-SV-PCI Multi-axis motion control card and redundantly actuated parallel mechanism of high-tech (Shenzhen) Company as the basis for building the motion control system structures as well as software development. Meanwhile, redundantly actuated parallel mechanism model is established based on a SimMechanics module in Simulink, which is the foundation of carrying out simulation experiments.Finally, the paper researches the position control and force control of redundantly actuated parallel mechanism. While Position control includes coordinate system of motion control, kinematics feedback control and PD control of joint space; And Force control includes impedance control and the force/position control. Then the position-based impedance control in the strategy of force control is improved in algorithm. In the paper, the experiments for coordinate system of motion control and kinematics feedback control is done, at the same time, the simulation experiments for PD control algorithms of joint space and improved position-based impedance control algorithm are carried out.