A Reconfigurable Pneumatic Bending Actuator with Replaceable Inflation Modules

Abstract

A fully reconfigurable, pneumatic bending actuator is fabricated by implementing the concept of modularity to soft robotics. The actuator features independent, removable, fabric inflation modules that are attached to a common flexible but non-inflating plastic spine. The fabric modules are individually fabricated by heat sealing a thermoplastic polyurethane-coated nylon fabric, whereas the spine is manufactured through fused deposition modeling 3D printing; the components can be assembled and dismantled without the aid of any external tools. The replacement of specific modules along the array facilitates the reconfiguration of the actuator's bending trajectory and torque output; likewise, the combination of inflation modules with dissimilar geometries translates to several different trajectories on a single spine and allows the actuator to bend into assorted, unique structures. A detailed description of the actuator's design is thoroughly presented. We explored how reconfiguration of the actuator's modular geometry affected both the steady state and the dynamic characteristics of the actuator. The torque output of the actuator is proportional to the magnitude of the pressure applied. The actuator was excited by sinusoidal and square pressure inputs, and a second-order linear fit was performed. There were no perceived changes in its performance even after 100,000 inflation and deflation cycles.

A Parallel, 2-DOF Exoskeleton for the Human Shoulder: Device Characterization and Preliminary Results on Healthy Subjects

“…Load bearing actuators must operate from the -180°to -90° A-A' angle range in order to maximize their utility. This behavior is consistent with that from our previous work (27,28). These actuators would supply approximately 7%, 24.6% and 25.8% of the torque necessary to maintain arm elevation of 90° for a typical, stretched, male arm with a mass of 3.5kg (32).…”

“…To avoid the complexities involved in using traditional robotic architectures, we employed a fabric-based, pneumatic soft actuator to drive a shoulder exoskeleton. The actuator was developed based on the hybrid fabric-plastic design and results we previously presented (27,28). The majority of the actuator is composed of nylon fabric, which resulted in negligible bending resistance as evidenced by its ability to trace its full range of motion with minimal input.…”

“…Their geometric parameters are listed in Table 1. Module widths were based on the lower 5th percentile of female upper arm diameters for B, and the lower 5th percentile of male upper arm diameters for C (27). All experiments were repeated three times, and the samples were dismounted and remounted before each repetition in order to minimize the effects of any actuator movement that may have occurred during a measurement.…”

“…Moreover, evidence regarding the efficacy of pneumatic shoulder exoskeletons is scarce. To the extent of the authors' knowledge, testing data on humans has only involved a limited number of subjects (23,27). An expanded test on a greater number of human subjects would provide a more conclusive picture on the effectiveness of these exoskeletons in performing rehabilitative tasks.…”

Sleeved Bending Actuators for Soft Grippers: A Durable Solution for High Force-to-Weight Applications

“…These actuators, developed for reef-sample collection, show payloads of up to 6 kg [10]. A modular bending actuator has also been developed using polyurethane-coated fabric pockets assembled on a 3D-printed spine [20]. This was experimentally shown to sustain 100,000 cycles while producing a torque proportional to the pressure.…”