Design and Engineering of AeroGrip

Abstract

This design project marks the collaborative efforts of Translas, a prominent welding company based in the Netherlands, and Skelex, a scale-up enterprise specializing in exoskeleton design. Translas developed the 8XE fume extractor torch. However, a common complaint of the new torch is its decreased usability and potential ergonomic risk. To address this problem, Skelex and Translas have united their expertise to develop an exoskeleton-lite solution, aimed at assisting welders in carrying the torch. The aim is to alleviate the physical strain of welding and enhance overall ergonomics. A literature review of welding, ergonomics, and exoskeletons reveal that musculoskeletal disorders form a significant societal problem with large financial losses, which provide opportunities for cutting-edge companies as Translas and Skelex, and form the groundwork for a problem definition, design goal, and drivers. Through a numerical model the specific ergonomic concerns of the 8XE torch are analysed, which is also used to assess the final design. It was found that generally static welding forces with the 8XE are within safe parameters as recommended by ergonomic experts. The bending stiffness of the 8XE cable contributes significantly to the wrist moment, being estimated to reach values of 0.5Nm in conventional welding, compared to the 0.7Nm contribution due to weight. Friction in the ball-and-socket joint, and inertia ore comparatively low, and do not significantly cause ergonomic concerns. An iterative prototyping phase diverges to explore various ways to offload the 8XE’s weight on the wrist to stronger body parts, converging to two good concepts. A simple strap off loading the weight on the wrist to the lower arm for a limited amount of welding positions, and an exoskeleton worn on the waist and shoulders carrying the full weight of the torch using a tool balancer. After three user tests, two of which with welders in industry, both concepts were combined which led to the creation of AeroGrip. AeroGrip is an exoskeleton-lite product that eases welding by changing the weight distribution on the upper extremities, improving ergonomics and helping welders ‘be their ultimate’; they can weld safely for longer, with more precision, whilst experiencing less strain. It is a system that attaches to the welding cable through a ladder strap and buckle. A hook attached to a Kevlar cable can be pulled out and attached to the special AeroGrip Gloves, which feature a leather tab with grommet. The Kevlar cable is attached to a power spring via a spool in the casing, which ultimately results in a Tension of ~12N. Two final user tests, and comparative numerical analysis show that AeroGrip eases welding, provides an ergonomic benefit, and is convenient to use. FEM analysis and friction analysis ensure feasibility, whilst an assembly plan and business case ensure viability.