Samet Ersoysal

Despite the increasing use of automation and digitalization in industrial workplaces, workers still have to handle heavy loads and have to perform strenuous, repetitive, long-term assembly tasks at head level or above, which may lead to degenerative musculoskeletal disorders. The growing trend towards wearable support systems has already resulted in a large number of exoskeletons being in research or commercially available. However, most of the support systems for industrial workplaces focus on the back and shoulders, but not the elbow joint. In a preliminary study, we presented a soft passive elbow exoskeleton, which was limited to static tasks, although dynamic support is necessary for most industrial tasks. Building upon that work, this paper presents an elbow exoskeleton that can be coupled to an existing shoulder exoskeleton. The developed prototype is designed to support the elbow flexion with a pneumatic actuator for industrial applications. The functionality of the prototype was tested on three male participants in one static and two dynamic tasks. The laboratory tests have shown that the exoskeleton reduced the mean muscular activity of the brachioradialis and biceps brachii in all tasks. Based on the results, the developed exoskeleton may potentially support the elbow flexion in industrial tasks, but further testing is needed to evaluate its biomechanical effects on the user.

In modern times, the collaboration between humans and machines increasingly rises, combining their respective benefits. The direct physical support causes interaction forces in human–machine interfaces, whereas their form determines both the effectiveness and comfort of the collaboration. However, their correct detection requires various sensor characteristics and remains challenging. Thus, this paper presents a developed low-cost sensor pad working with a silicone capsule and a piezoresistive pressure sensor. Its measurement accuracy is validated in both an isolated testing environment and a laboratory study with four test subjects (gender-balanced), and an application integrated in interfaces of an active upper-body exoskeleton. In the material-testing machine, it becomes apparent that the sensor pad generally features the capability of reliably determining normal forces on its surface until a certain threshold. This is also proven in the real application, where the measurement data of three sensor pads spatially embedded in the exoskeletal interface are compared to the data of an installed multi-axis load cell and a high-resolution flexible pressure map. Here, the consideration of three sensor pads potentially enables detection of exoskeletal support on the upper arm as well as “poor” fit conditions such as uneven pressure distributions that recommend immediate system adjustments for ergonomic improvements.

In industrial workplaces, strenuous, repetitive, and long-term tasks at head level or above as well as carrying heavy loads may lead to musculoskeletal disorders of different task dependent body parts. With an increasing trend towards wearable support systems, there is already a large quantity of exoskeletons that may support the user during movements, or stabilize postures, in order to reduce strain on various parts of the body. However, most commercially available exoskeletons mainly focus on the back and shoulder support. Only a few of them address the elbow joint, despite it being prone to injury. Therefore, this paper discusses different possible design and control concepts of modular elbow exoskeletons. The modular architecture potentially enables coupling to existing commercial- and research-associated systems, through appropriate interfaces. Different morphological structures and control mechanisms are assessed in respect to their ability to extend common exoskeletons for back and shoulder support. Based on these considerations, a first functional passive prototype is presented, which supports the flexion of the elbow joint and can be coupled to an existing exoskeleton. In future work, the prototype may be used for further elaboration and practical investigations in laboratory settings to evaluate its technical functionality and biomechanical effects on the user.