A review of the design of load-carrying exoskeletons

Abstract

The increasing necessity of load-carrying activities has led to greater human musculoskeletal damage and an increased metabolic cost. With the rise of exoskeleton technology, researchers have begun exploring different approaches to developing wearable robots to augment human load-carrying ability. However, there is a lack of systematic discussion on biomechanics, mechanical designs, and augmentation performance. To achieve this, extensive studies have been reviewed and 108 references are selected mainly from 2013 to 2022 to address the most recent development. Other earlier 20 studies are selected to present the origin of different design principles. In terms of the way to achieve load-carrying augmentation, the exoskeletons reviewed in this paper are sorted by four categories based on the design principles, namely load-suspended backpacks, lower-limb exoskeletons providing joint torques, exoskeletons transferring load to the ground and exoskeletons transferring load between body segments. Specifically, the driving modes of active and passive, the structure of rigid and flexible, the conflict between assistive performance and the mass penalty of the exoskeleton, and the autonomy are discussed in detail in each section to illustrate the advances, challenges, and future trends of exoskeletons designed to carry loads.

Exoskeletons: A challenge for development

“…Technical details of control strategies are rarely specified in detail. They are discussed rather superficially as a means to increase stability, performance, and achieve natural movements (Gupta et al, 2019 , 2020 ; Chen et al, 2020 ; Kapsalyamov et al, 2020 ; Schnieders and Stone, 2020 ; Pérez Vidal et al, 2021 ; Plaza et al, 2021 ; Rodríguez-Fernández et al, 2021 ; Liang et al, 2022 ; Massardi et al, 2022 ; Tijjani et al, 2022 ). The design of lower limb exoskeletons is a focus topic on its own, especially in rehabilitation and assisted living use cases.…”

A Real-Time Control Method for Upper Limb Exoskeleton Based on Active Torque Prediction Model

“…In order to reduce the overall weight and ensure the strength of the instrument, the exoskeleton prototype was developed with a lightweight design, mostly made of carbon fiber and ABS, and weighed around 1.5 kg overall. Meanwhile, the exoskeleton adopted the design idea of the motor side and synchronous belts to transfer the torque to the elbow joint [25]. The side position of the motor reduced the volume, and the elbow joint and synchronous belt transmission provided steady and effective duplex torque transmission.…”

Neural Network Robust Control Based on Computed Torque for Lower Limb Exoskeleton

“…In such case, the exoskeleton usually works in conjunction with the corresponding trolley, which provides support and guidance to ensure safety and keep balance for the wearers [10,11]. In military and industrial fields, exoskeletons transmit the load borne by the wearer (such as backpacks or heavy tools) to the ground [12,13], reducing fatigue and enhancing endurance and load capacity. Currently, lower limb exoskeletons are applied in different scenarios and the collaboration modes can be generally categorized into trolley-assisted mode, independent mode, and load-bearing mode.…”