Toward the Development of Large-Scale Inflatable Robotic Arms Using Hot Air Welding

The manufacturing method of soft pneumatic robots affects their ability to maintain their impermeability when pressurized. Pressurizing them beyond their limits results in leaks or ruptures of the structure. Increasing their size simultaneously increases the tension forces within their structure and reduces their ability to withstand the pressures necessary for them to operate. This article introduces the use of hot air welding to manufacture three-dimensional inflatable elements containing only lap seals which can sustain larger tension forces than the fin seals used in most other inflatable robotic arms. This manufacturing technique is then used to form inflatable joints with 2-degrees of freedom (DOFs), which can be assembled to form 6-DOFs robotic arms. A dual-arm inflatable robot was built using two arms each with a length of 85 cm, was capable of lifting payloads up to 3 kg, had a large range of motion, and was able to lift misaligned boxes using its two arms relying only on friction force by pushing on both sides of the box. The arm concept was then scaled to form a robotic arm with a length of nearly 5 m, which was able to pickup and place a basketball in a basketball hoop from the free-throw line several meters away. The present work advances the state of the art in building large-scale soft robotic arms.