To obtain better flexibility and multifunction in varying practical applications, several typical configurations of a modular reconfigurable cable-driven parallel robot are analyzed in this article. The spatial topolo...
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To obtain better flexibility and multifunction in varying practical applications, several typical configurations of a modular reconfigurable cable-driven parallel robot are analyzed in this article. The spatial topology of the modular reconfigurable cable-driven parallel robot can be reconfigured by manually detaching or attaching the different number of modular branches as well as changing the connection points on the end-effector to satisfy diverse task requirements. The structure design of the modular reconfigurable cable-driven parallel robot is depicted in detail, including the design methodology, mechanical description, and control architecture. The inverse kinematics and dynamics of the modular reconfigurable cable-driven parallel robot considering diverse configurations are derived according to the vector closed rule and Lagrange method, respectively. The numerical simulation and related experiments of a typical configuration are achieved and analyzed. The results verify the effectiveness and feasibility of the inverse kinematics and dynamics models for the modular reconfigurable cable-driven parallel robot.
When cable-drivenparallelrobots (CDPRs) are doing some complex work, obstacles in the environment will interfere with cables and the mobile platform. It is a meaningful work to avoid these disturbances by planning t...
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ISBN:
(纸本)9798350350319;9798350350302
When cable-drivenparallelrobots (CDPRs) are doing some complex work, obstacles in the environment will interfere with cables and the mobile platform. It is a meaningful work to avoid these disturbances by planning the path of CDPRs. This paper presents an optimal path planning strategy for a reconfigurable CDPR. By a variant of Rapid-exploration Random Tree (RRT) to find the optimal collision avoidance path gradually, Artificial Potential Field (APF) is used to guide the generation of random tree nodes, reducing the time of finding the path, and ensuring the safe distance between the platform and obstacles, and generating the shortest collision-free path. Post-processing algorithm reduce the number of path points. Detect whether the generated path will cause obstacles to interfere with the cable. If there is interference, optimize the robot's stiffness and minimize cable tensions to determine the optimal configuration. By adjusting the location of the cable connection points on the fixed frame, the obstacle avoidance of the cable is realized. The simulation results demonstrate the RRT*-APF hybrid path planning algorithm's ability to successfully find the path to avoid collision of the mobile platform in the environment with obstacles, the reconstruction algorithm can find the best collision-free configuration of the cable.
The movable anchor points make reconfigurable cable-driven parallel robots (RCDPRs) advantageous over conventional cable-drivenparallelrobots with fixed anchor points, but the movable anchor points also introduce an...
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The movable anchor points make reconfigurable cable-driven parallel robots (RCDPRs) advantageous over conventional cable-drivenparallelrobots with fixed anchor points, but the movable anchor points also introduce an inherent problem-reconfiguration planning. Scholars have proposed reconfiguration planning approaches for RCDPRs, taking into account the statics and kinematics of RCDPRs. However, a real-time reconfiguration planning approach that considers the dynamics of an RCDPR and is computationally efficient enough to be integrated into the RCDPR's dynamic controller is still not available in the literature yet. This paper develops a real-time reconfiguration planning approach for RCDPRs. A novel reconfiguration value function is defined to reflect the "value" of an RCDPR configuration and provide a reference index for the reconfiguration planning of an RCDPR. And then, the developed approach conducts reconfiguration planning based on the value of RCDPR configurations. The developed approach is computationally efficient, reducing the reconfiguration planning time by more than 93%, compared to single iteration of a box-constrained optimization-based reconfiguration planning approach. Such a high efficiency allows the developed approach to be integrated into an RCDPR's dynamic controller that usually runs with a high frequency. Integrating reconfiguration planning and dynamic control enhances the control performance of the RCDPR. To verify the effectiveness of the developed approach and the integration of reconfiguration planning and dynamic control for RCDPRs, a case study of an RCDPR with seven cables and four movable anchor points is conducted.
In this paper, a method for computing the optimal actuation of reconfigurable cable-driven parallel robots is presented. By using this method, the imperfect ability in exerting torque and limited orientation workspace...
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In this paper, a method for computing the optimal actuation of reconfigurable cable-driven parallel robots is presented. By using this method, the imperfect ability in exerting torque and limited orientation workspace of these robots may be improved. In a cable-drivenparallelrobot with reconfigurability, the attachment points of cables on the base are adjusted with regard to the movement of the end-effector on a trajectory. In such a design the redundant degree-of-freedom of the robot is increased accordingly. For an arbitrary pose of the end-effector, a spherical zone is defined in which the called wrench-closure condition is satisfied for a prescribed range of orientation. Taking the volume of such zone into consideration the optimal configuration of the robot may be determined. This configuration is found by appropriately changing the position of the moving attachment points on the base of the robot. By repeating this computation for a number of points on a specified trajectory, appropriate actuation plans are achieved. The computed optimal actuation guarantees balance of any external wrench by tension force of cables when the end-effector moves close to its trajectory. For a case of spatial reconfigurable cable-driven parallel robot, the optimal actuation is found based on Particle Swarm Optimization and performance of the robot is compared to the one with fixed cable attachment points on base. The result shows significant improvement of the performance of reconfigurable spatial cable-drivenparallelrobot.
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