Assistive Suit development for enhancing agricultural task efficiency

2020.01.01. - 2022.12.31.

Apr 21, 2025 Mechanical Intelligence

1. Funding Agency

Ministry of Agriculture and Forestry of the Republic of Korea

2. Motivation

Agricultural workers frequently engage in repetitive lifting, bending, and stoop-to-stand motions under unstable terrain, often carrying heavy produce or tools. These movements are primary contributors to lower-back disorders, particularly in aging rural labor populations.

Despite the availability of industrial exoskeletons, most are unsuited for field conditions due to weight, rigidity, or energy requirements. This project aims to deliver a lightweight, compliant hip-assist wearable robot that reduces musculoskeletal strain and supports biomechanical load transfer during field harvesting and transportation tasks.

3. Objectives

This project proposes a compact, twisted string actuator (TSA)-based hip exoskeleton tailored for lifting tasks in agricultural environments. The goal is to minimize back load during stoop-to-stand transitions by converting TSA-induced contraction into rotational hip assistance.

Using anthropometric modeling, we designed a system that provides 15–30 Nm torque support while weighing less than 6 kg, including battery and controller. Key design constraints included back-drivability, portability, and torque-to-weight optimization, with string routing and pulley design tuned to maximize transmission efficiency for ground-level lifting motion.

4. Results

The developed TSA-based hip exoskeleton achieved 30 Nm peak torque and up to 150°/s angular speed at the hip joint, meeting dynamic requirements for lifting 10-kg loads.

  • Weight: The full system weighs 6.0 kg, including harness, carbon frame, dual actuators, and onboard power/control modules.
  • Power: Energy consumption remained below 55 W during peak operation.
  • Performance: The nonlinear TSA transmission profile closely matched the torque-speed pattern of human hip motion during lifting.
  • Validation: Experimental validation with human subjects confirmed biomechanical assistance and reduced lumbar loading during repeated harvesting motion.

  • H. -S. Seong, D. -H. Kim, I. Gaponov and J. -H. Ryu, “Development of a Twisted String Actuator-based Exoskeleton for Hip Joint Assistance in Lifting Tasks,” 2020 IEEE International Conference on Robotics and Automation (ICRA), Paris, France, 2020, pp. 761-767.

  • String actuator-based exoskeleton robot (US Patent 12,145,261)

  • Hip-joint exosuit based on twisted string actuation (Application Number: PCT/KR2021/095061, International)

6. Contact

  • Hyeonseok Seong