Autonomous robot with e-spool energy chain automates unloading of cargo

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• What was needed: e-spool energy chain, chainflex cables
• Requirements: A space-saving cable guide was needed to supply the robot. As it rubs against the concrete floor, it also had to be wear-resistant.
• Industry: Robotics, instrument logistics
• Success for the customer: With the e-spool including spring retraction, all cables can be rolled up compactly. No special solution had to be designed and the project budget could be adhered to.

This 7-axis robot arm was assembled on a mobile crawler platform and is used in lorries in the production industry. Thanks to a sophisticated gripper, vision system and artificial intelligence developed by the Michelin study and research centre in Ladoux, the robot arm identifies and grips the products and places them on a conveyor belt under the robot, which transports the products to their processing area.

In manual mode (radio-controlled), the platform can travel with the robot in all directions, with the destination being the loading/unloading dock. Once on the dock, it switches to autonomous mode. However, when working in the narrow trailer of a lorry, the robot can only move forwards and backwards to a limited extent and can only turn slightly to re-centre. This posed a space problem, especially for guiding the numerous power, control and pneumatic cables from outside into the trailer where the robot works. Alternatives such as a battery for the energy supply or a motor were out of the question due to the robot's size and weight restrictions.

Instead, an energy chain system was chosen, which is pulled horizontally behind the robot over concrete and the wooden or plastic formwork of the lorry trailer with a minimum travel of 14m, a speed of 12m/min and acceleration of 1m/s². The small height difference between the dock and trailer also posed a challenge and required a cable guide that was as wear-free as possible. As the chain would be slightly off-centre from the track of the mobile platform, it had to be in a position to accept twisting/deformation.

In order to fulfil the special requirements of the cable guide, we worked closely with the customer to find the best technical solution.

In the end, the choice fell on an e-spool with spring retraction, which today enables the engineers to guide all power and data cables as well as pneumatic hoses safely to the robot platform.

To ensure that the unwound energy chain could also move in the Y direction, the e-spool was assembled on a turntable with the 1400 series energy chain. Another specification concerned the last links of the chain, which were assembled in reverse so that the cable guide is closer to the floor when the e-spool is unrolled.

Additional sensors were also installed on the energy chain to stop the mobile platform before the chain runs out. The e-spool made it possible to wind up the cables in a confined space. Thanks to the integrated spring retraction system, the engineers were able to dispense with a motorised system for winding up the chain.

Unlike a battery-powered or motor-driven system, the robot could thus be kept as light and slim as possible. The e-spool also meant that the project team's budget for the cable guide could be adhered to. In addition to the energy chain, we also supplied the cables and hoses used in it. These were primarily chainflex motor cables, chainflex control cables and a pneumatic hose.