Pneumatic soft exoskeleton supports arm muscles during heavy work

A research team from the University of Texas Arlington (UTA) has developed a soft exoskeleton that relieves workers during heavy tasks such as lifting and performing repetitive mechanical activities with their arms. The exoskeleton, named “Pneumatically Actuated Soft Elbow Exoskeleton” (PASE), operates with air pressure and is strapped to the arm.

PASE was developed to minimize chronic strain on the arm and elbow, write the UTA scientists in the study “Design, development, and evaluation of a pneumatically actuated soft wearable robotic elbow exoskeleton for reducing muscle activity and perceived workload,” which was published in the Journal of Rehabilitation and Assistive Technologies Engineering. The goal: to relieve workers during heavy tasks to prevent muscle and skeletal diseases.

Lightweight Exoskeleton Made of Soft Material

The robot for the arm consists of a lightweight actuator made of soft silicone at its core. The actuator is attached to a carbon fiber-onyx base plate, which is encased in a soft neoprene sleeve. This allows the exoskeleton to be attached to the arm with three straps without hard components coming into contact with the arm and impairing the user. Furthermore, the silicone in combination with the lightweight carbon fiber plate reduces the weight of the exoskeleton compared to conventional robotic aids for the arms. The total weight, including fastening straps, is 638 g. This is intended to make wearing it comfortable.

The actuator comprises several air chambers into which air is blown via a single hose through a valve. Depending on the pressure of up to 50 PSI (just under 3.5 bar), the actuator bends to support the natural curvature of the elbow. Excess air escapes again via a controlled valve when the arm relaxes. A simple Inertial Measurement Unit (IMU) serves as a sensor, measuring acceleration and rotational movements and determining the arm's position in space.

To test the functionality and effectiveness of PASE, the researchers conducted a study with 19 participants aged 18 to 45. They had to perform three tasks: manually lifting various weights, performing simple assembly work, and drilling holes with a drill. The scientists found that muscle activity in the biceps and triceps decreased by up to 22 percent with the use of the exoskeleton. Participants reported that they perceived the workload to be significantly lower than without the exoskeleton.

Encouraged by these results, the scientists want to expand their research and have submitted a proposal to the National Science Foundation. It is intended to fund a project to develop an exoskeleton that can fully assist the upper limbs in their movements. In addition to the elbows, wrists and fingers are also to be supported.

(olb)