| Tunnel boring machine(TBM)as a complex large-scale tunnel construction equipment plays an important role in national infrastructure.Disc cutter replacement as an important part of tunnel construction.However,the current dangerous and inefficient manual tool replacement method is not compatible with the requirements of safe,efficient and intelligent tunnel construction.Especially in the high pressure,high humidity slurry shield machine's operating environment,the safety of the tool changers is under great threat.“Dangerous tool change” already became the difficult problem that restricts industry development.So that,the safe operation mode of robot tool change has become an inevitable trend.This article proposal a design plan for the tool change robot based on the operating environment of heavy load and small space in slurry shield.Take 12 m diameter shield as an example to carry out detailed structural design,trajectory planning and discussion of motion control,and the main works are as follows:(1)Design of tool changing robot for slurry shield under large load,small space and long span: The use of metamorphic mechanism can change the configuration characteristics according to functional requirements or environmental changes.The operation area of the tool changing robot is divided into four task areas,and the configuration of each task is designed.Finally,the topology of each configuration is synthesized to obtain the robot structure scheme that meets the requirements of tool changing.Further detailed structural design is carried out to obtain a 7-DOF hydraulic drive's tool change robot which can adapt to the 12 m diameter shield.(2)Trajectory planning designing based on optimal combination of impact and time: Taking jerk as the objective of optimal impact,the impact characteristics of multiple polynomial curves are analyzed,and the higher-order polynomials with high-order and continuous characteristics are obtained.At the same time,the trapezoid velocity curve has the characteristics of the shortest movement time.Combining high-order polynomial and trapezoid velocity curve,a trajectory planning method based on the combination of time and impact is proposed and applied.The results show that the end movement has neither flexible impact nor rigid impact,and the replacement time of single tool is within 30 s to 70 s.(3)Establishment of kinematics and dynamics model of tool-changing robot.The schematic diagram of the robot mechanism is constructed.DH method was used to establish kinematic model.At the same time,monte-carlo method combined with kinematics method is applied to verify that the tool changing range of the robot can reach 100%.Newton Euler method is used to establish the dynamic model of the multi degree of freedom serial tool changing robot.Adams is used to verify the correctness of the kinematic and dynamic model,which lays the foundation for the control of the robot.(4)Robot control algorithm design based on dynamic model compensation: The control based on model,PD control and PD control based on model compensation are studied respectively.The results show,model-based control cannot be directly applied to control due to the inaccuracy of model establishment.PD control has the problem of unstable control due to the coupling effect of multiple joints.PD control based on model compensation has good accuracy and stability.At last,Adams and Matlab were used to build the robot control system to verify the feasibility of the algorithm. |
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