scholarly journals Dynamic Control of Parallel Robots Driven by Flexible Cables and Actuated by Position-Controlled Winches

2019 ◽  
Vol 35 (1) ◽  
pp. 286-293 ◽  
Author(s):  
Jeremy Begey ◽  
Loic Cuvillon ◽  
Maximilien Lesellier ◽  
Marc Gouttefarde ◽  
Jacques Gangloff
Author(s):  
Jinwoo Jung ◽  
Jinlong Piao ◽  
Eunpyo Choi ◽  
Jong-Oh Park ◽  
Chang-Sei Kim

Abstract A cable-driven parallel robot (CDPR) consists of an end-effector, flexible lightweight cables, pulleys, winches, and a rigid base frame. As opposed to the rigid links of the traditional serial robots and parallel robots, the flexible lightweight cables allow the CDPR to easily achieve the high speed, heavy payload manipulation, and scalable workspace. Especially, the conventional high-speed pick and place operation can be realized due to the lightweight of its flexible cables. However, the flexibility of the lightweight cables can introduce a considerable vibration problem to the high speed cable robot system. One of main causes can be a cable tension difference between initial pre-tension and winding tension around a drum of the winch-motor actuator. To effectively investigate the effect of the tension around the drum on the high speed manipulation of the cable robot system, the spatial eight-cable high speed cable robot was reduced to the horizontal two cable system. The reduction of the number of the cable enables us to minimize the influences from the other factors such as the cable sagging and the geometric errors. A series of experiments was conducted using the combinations of the low and high initial pre-tensions and low and high tensions around the drum. The experimental results clearly show that the low tension around the drum can cause the vibration problem during the high speed pick and place operation. Also, it demonstrates that securing the drum tension similar to the initial pre-tension can effectively reduce the magnitude of the vibration.


2021 ◽  
Vol 143 (8) ◽  
Author(s):  
Naijing Lv ◽  
Jianhua Liu ◽  
Yunyi Jia

Abstract Due to the flexibility and high degrees-of-freedom of flexible cables, their dynamic modeling and precise control are challenging. In this paper, the dynamic modeling and control of flexible cables with human-like dual manipulators are studied to deploy them on a plane and form the desired shapes automatically. First, we establish a dynamic model of flexible cables based on a discrete elastic rod model. This model can simulate their stretching, bending, and twisting deformations. Then, we consider the collisions, contacts, and frictions between the flexible cables and the plane, add kinematic constraints to the model, and finally obtain an implementable dynamic solution of the model. Next, we propose dynamic control schemes including parallel dual-arm control and coordinated dual-arm control to deploy the flexible cables on a plane and form the desired shapes for dual-arm controls. Finally, experimental and simulation studies are carried out to illustrate the effectiveness of the dynamic model and the validity of the control schemes. The results show that the model can successfully demonstrate the deformations of flexible cables, and the proposed control schemes can successfully manipulate flexible cables in different tasks.


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