| The reconfigurable cable-driven parallel robot is a type of robot in which the cable position distribution is changed by changing the cable point or introducing other mechanisms.It is mainly divided into two categories: one is the reconfiguration of the cable and the end effector,and the other is the reconfiguration of the cable and the rack.This paper mainly studies the analysis and control of the work space of the second type of cable and frame reconfiguration.RCDPRs can give full play to its large working space,better sports performance,increase system rigidity,greatly increase payload,and easy to reconfigure.This article mainly takes 8 cables 6 degrees of freedom and 4 cables 3 degrees of freedom RCDPRs as the research objects,through theoretical analysis of 4 cables 3 degrees of freedom,8 cables 6 degrees of freedom RCDPRs,and finally controlled by 4 cables 3 degrees of freedom RCDPRs due to environmental constraints.System construction and theoretical verification,and repeated errors were measured.The main research contents are as follows:The constrained parallel robot was selected according to the working conditions,and the8-cable 6-DOF structure model was established,and the kinematics positive solution was calculated for this model.Newton iteration was used and the 2-norm editing optimization algorithm was introduced to perform kinematics analysis;combined with reality The statics model and dynamics model are established under the working conditions,and a unified expression is obtained.Defines the force-enclosed working space and force-accessible working space of RCDPRs.In view of the longer calculation time of the force-enclosed workspace of RCDPRs,methods such as inequality derivation,matrix transformation,rank judgment and other methods are used to optimize the algorithm to shorten the calculation time;the force-reachable workspace algorithm of RCDPRs is compiled,and preliminary simulation is performed to verify the correctness of the algorithm.Algorithm basis for influencing factor analysis.Considering the advantages of further expanding the work space,motion performance,system stiffness,effective load,easy reconstruction,etc.,through the statistics of the number of discrete points in the work space,after normalization,the factors of gravity,maximum cable force,and minimum cable force are analyzed.The magnitude of the influence of 4-cable and3-freedom;Z-direction discrete point position change factor has a greater impact on the 8-cable and 6-degree-of-freedom workspace,and the translational isotropy index is introduced for evaluation.The software and hardware of the RCDPRs experimental platform are designed and implemented,and the measurement scheme is proposed.The overall plan of the control system is designed: in terms of hardware,it mainly introduces the host computer,PC controller,PLC,and servo system;in terms of software,it introduces the principle and application of OPC interface and software design.Aiming at the inaccuracy of the original measurement,a combination of visual measurement and real-time image capture is proposed to measure the trajectory and repeat error,and the obtained repeat error is within 1mm.Only the work space and RCDPRs of cable-driven parallel robots are studied separately,and the two are rarely combined.This dissertation combines the two researches,focusing on the influencing factors of the workspace of RCDPRs and related issues of the control system.On the one hand,it fills the theoretical blank of the working space of RCDPRs,and on the other hand,it lays the foundation for the application of cable-driven parallel robots in large-scale printers. |
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