Cable-driven parallel robots with on-board active devices – DexterWide

Two main types of embedded system were selected, modeled, developed and experimentally demonstrated during the DexterWide project. The first consists of an industrial robot (manipulator arm) and a large parallel cable robot. The industrial robot is placed under the mobile platform of the cable robot. This system allows complex movements and tasks to be performed within a large workspace provided that the coordination and synchronization of the movements of the two robots is mastered. Also, various issues of modeling, movement planning, collision avoidance and communication between robot controllers must be addressed. The second type of embedded system aims to quickly dampen the vibrations of the mobile platform of the cable robot. These vibrations can have various origins and can notably be caused by rapid movements of an embedded industrial robot. Different technologies for implementing such a stabilizer have been studied and tested. Advanced control strategies using dynamic modeling of the stabilizer and exteroceptive sensors have notably been proposed and experimentally validated.

Two main types of embedded system were produced and experimentally demonstrated during the DexterWide project. The first consists of an industrial robot (manipulator arm) and a large parallel cable robot. The industrial robot is positioned beneath the cable robot's moving platform. This system enables complex movements and tasks to be carried out in a large workspace, provided that the coordination and synchronization of the movements of the two robots is mastered. In addition, various issues of modeling, motion planning, collision avoidance and communication between robot controllers were addressed. The second type of embedded system is designed to rapidly dampen vibrations on the mobile platform of the cabled robot. These vibrations can have a variety of origins, and in particular can be caused by the rapid movements of an on-board industrial robot. Various technologies for implementing such a stabilizer have been studied and tested. In particular, advanced control strategies using dynamic stabilizer modeling and exteroceptive sensors have been proposed and experimentally validated.

The demonstrations carried out during the project (contactless movement, drilling, etc.) and the active vibration damping demonstrations demonstrate the functionality of the concepts on a representative scale. The main application areas targeted are the nuclear industry, large structures, aeronautical construction, as well as the naval/defense industry. For example, in the nuclear industry, the advantages of parallel cable robot technology are the simplicity of implementation, the large work volume and the lightness of the system. Embedding an industrial robot on the mobile platform of the cable robot opens the door to carrying out more complex operations such as dose rate or contamination assessment, area marking, sample collection, sanitation by mechanical action or projection, or dismantling by disassembly, cutting, and waste recovery.

Begey, J.; et al. Dynamic Control of Parallel Robots Driven by Flexible Cables and Actuated by Position-Controlled Winches. IEEE Transactions on Robotics. 2019.

Michelin, M.; et al. Path Following Demonstration of a Hybrid Cable-Driven Parallel Robot. In Cable-Driven Parallel Robots, Springer. 2021.

Amortissement d’oscillations : youtu.be/tN5UPqr268o
Démonstrations robot à câbles équipé du robot industriel : youtu.be/g0_OqK-ZWdU, youtu.be/yU3Lx-1FL1M

Dépôt de brevet : EP3318369 (A1) - CABLE DRIVEN PARALLEL MANIPULATOR.

The project DexterWide deals with robotic systems consisting of a cable-driven parallel robot (CDPR) equipped with an industrial robotic arm, a relevant combination in a number of industrial applications involving dexterous tasks over wide workspaces. Examples of typical applications that may benefit from this new technology include production, handling, and inspection in naval construction, renewable energy, aeronautics, and nuclear industries and in civil engineering. Robotizing some of these applications could relieve workers from dangerous or tedious tasks, improve production time and quality and thus preserve the competiveness of some key national industrial sectors. The DexterWide project is endorsed by the PNB (“Pôle de l’industrie nucléaire”).
Three archetypal applications will be demonstrated in the project:
- contactless application: spray painting
- “interacting application” #1: plastic or metal cutting with cut-off wheel
- “interacting application” #2: core drilling in various materials
The project will focus on cases where the influence of the robotic arm on the CDPR statics and/or dynamics is significant and cannot be neglected. The challenges to be faced are the flexible nature (low stiffness) of the CDPR, whose mobile platform is the supporting base of the on-board robotic arm, and the actuation and kinematic redundancies of the whole robotic system. To face these challenges, two means will be investigated:
1. The use of additional devices, on-board the CDPR mobile platform, that allow for active control of the overall center of mass (CoM) location and for active stabilization (vibration compensation).
2. Robot planning and control strategies using all available control inputs (CDPR winches and platform on-board actuations including the robotic arm actuators) to fully benefit from the redundancies present in the system.
Actuated mechanical devices consisting of one or several moving masses on-board the CDPR platform will be proposed. The motions of these masses will be coordinated with the motion of the on-board robotic arm so that the position of the CoM of the whole system is kept constant or within a given acceptable range. Thanks to such an on-board active device, it is expected that the CDPR does not have to be oversized with respect to the on-board robotic arm and also that the postures and motions of the robotic arm do not have to be strongly restricted. For active stabilization (vibration compensation), we will consider using all available control inputs, but also additional devices such as reaction wheels, control moment gyros and compressed air jets.
The second means, planning and control strategies, aims to properly and efficiently deal with the proposed robotic system which has kinematic and, possibly, actuation redundancies that need to be resolved. Moreover, advanced control strategies will be used to allow for efficient active stabilization and to enhance dynamic performances, which are expected requirements to successfully demonstrate the three selected applications (painting, cutting and core drilling).