Motion Analysis And Control Of A Four-cable Driven Translational Parallel Robot

The four-cable-driven translational parallel robot with a wide motion in stadium,do with low-frequency vibration. It makes the high precision camera installed on theactuator difficult to stabilize, reducing the effect. Dynamic equation of the system isestablished which is based on the idea of finite element. Then the thesis analyzes thevibration of the system in the motion. The vibration of the system is reduced withdigital PID control strategy successfully to improving the performance.First of all, this thesis analyzes the kinematics model and reversed kinematicsmodel and gets the nonlinear mapping from the actuator position to the cable length.Secondly, considering the influence of cable section quality and elastic extend, the finiteelement model (FEM) is set up. According to the elasticity, gravity, damping force andinertial force of the cable segment, the dynamics equation of flexible cable isestablished by Newton’s method. After that, this thesis builds the system dynamicsmodel combining the actuator and cable. Thirdly, the dynamics model is simulatednumerically with MATLAB to verify the dynamics model. This paper analyzes thevibration condition on the cases of different path, different speed and acceleration.Finally, digital PID control with feedback of the cable length is used, which adjusts thecontrol cable length in real-time to reduce the vibration of the system. Considering theengineering application, this thesis discusses the control algorithm, sampling method offeedback system and feedback calculation methods of cable length. The control strategyis validated to be effective.