| The inspection of cutting tools is one of the important topic in shield tunneling.It's featured with narrow working space,high ambient pressure and humidity,making human intervention risky and inefficiency.With slender structures,hyper-redundant degree of freedoms and remote cable drives,snake-arm robot has broad application prospects in confined space and hazardous environment.The snake-arm robot assisted tool inspection system can improve the efficiency and flexibility,avoid the downtime delay and intervention risk.It's of great significance for the safe and efficient construction of shields.To apply the snake-arm robot to tools inspection,in this paper,researches on light and modular mechanical design,kinematics of cabledriven hyper-redundant manipulator,multi-mode motion planning and control of cable-driven system are made.And a user interface and virtual simulation environment are developed.The main contents are as follows:(1)Hollow arms and joints,together with compact cable configurations and actuator modules are designed.The axis-angle and spatial bending conversion of universal joints,and inverse kinematics between cable space and joint space are used for the analysis of the maximum cable displacement.And a min-max linear programming method is proposed to compute the maximum cable tension.Then selections for main actuator elements are given.(2)Kinematics mappings between the cable space,joint space and Cartesian space are established.An improved tip following method for the inverse kinematics between joint space and Cartesian space is proposed.Comparisons of 5 algorithms demonstrate the improved efficiency,and optimized performance of joint limits and configuration deviations.For the nonlinearity and coupling of forward kinematics between cable space and joint space,the analytical solution of the Jacobian matrix is formulated.Geometric approach is used to derive the accurate boundary of 2D and 3D workspace.Results compared with the numerical method show the correctness and effectiveness for the analysis of boundary and internal morphologies.(3)For shape and pose tuning tasks under simple environment,spatial bending motion planning of individual joint and Jacobian-based Cartesian motion planning are investigated separately.For the navigation under unstructured environment,an online motion planning method based on incremental path planning and improved tip following are proposed.In addition,it's generalized to following motion planning of an arbitrary midarm.For the global obstacle avoidance under confined space,a path following motion planning is realized with further constraints on joint positions.Through simulations on each of the 4 motion modes,the effectiveness is illustrated.(4)A hierarchical control architecture is designed.Then the dynamics of snake-arm robot is modeled using Newton-Euler method,and an optimization and control strategy of cable tensions is presented based on computed torque method.The rationality of cable tensions,the accuracy and robustness of the trajectory tracking control are validated by simulation.(5)A ROS-based software platform is developed.The description of cable transmission,command mappings and algorithms of all above technologies are implemented.And the application of human-computer interaction,motion planning and control are tested on it.Results verify the system is effective and complete. |
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