Research On Kinematic Optimization Design Of Mutual-pulled Planar Cable-driven Parallel Robot

As the volume of world hungry and obese population people is increasing.Deep sea farming is an important way to provide an efficient and healthy food supply.Deep-sea fishing ground is an important equipment that fully utilizes the marine environment to meet human needs.The main structure of the deep sea fishing ground is a regular polygonal prism,which is immersed in seawater for a long time.The side nets are prone to grow aquatic plants and affect the breeding environment.Considering the cleaning of the side nets of deep sea fishing grounds,this article uses a parallel cable mechanism to complete the function of cleaning the side nets of deep sea fishing ground.A series of researches are conducted on cable parallel mechanism,the main contents of which are as follows:First,based on the kinematics model of the cable parallel mechanism,the unidirectional and bounded constraints of the cable force are comprehensively considered,and the cable force solution is converted into an optimization problem.Regarding the characteristics of the cable force distribution with different p-norms as the objective function,the differences in solution of each norm and the influence on the cable force distribution are explored by geometric methods.The simulation results show that the uniform distribution performance of cable force solved by 2~4 norm is better.The method is used to analyze the cable force distribution of several common cable parallel mechanisms.Then,an evaluation index of cable force uniformity based on the cable vector is proposed.The correction value of the modulus length of the cable direction vector and vector is used as an index to evaluate the uniform distribution of the cable forces,which can better reflect the difference of the cable forces in different poses.Compared with the cable force standard deviation evaluation index,the evaluation index based on the cable vector does not need to calculate the size of the cable force,which avoids the influence of different solution methods,and the order of magnitude of the index does not change with the order of the cable force.Which Suitable for cable force evaluation without external force.In order to meet the needs of automatic underwater cleaning of the side facades of deep sea fishing ground,a 4-cable-driven flat cleaning robot is designed.The cables are arranged in pairs,and the exit points of adjacent side nets are arranged in a height difference to avoid interference in the operation of cable parallel mechanism.According to the requirement of underwater working condition,the buoyancy control strategy of cable parallel robot is proposed to improve the workspace of cleaning robot by adjusting buoyancy.The changes of the workspace of the robot under the conditions of fixed buoyancy and depth-dependent buoyancy are explored.Taking into account the stiffness isotropy and average stiffness of the cable-parallel mechanism,the optimal workspace of the cable-parallel cleaning robot is obtained,which meets the cleaning requirements of the side nets of deep sea fishing ground.Finally,based on the evaluation index of the standard deviation of the cable force,the orientation angle of the cable parallel mechanism is optimized.In orientation optimization,considering the continuity of orientation changes,a range of orientation angle constraints for orientation workspace is proposed.After the optimization of the orientation,the uniformity of the cable force is significantly improved,the stiffness and stability of the cable-parallel mechanism is improved,and the stability and efficiency of the robot's work is guaranteed.