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Quantifying Ergonomics in the Elevate Soft Robotic Suit

Peter Bryan, Rejin John Varghese, Dario Farina

TL;DR

This study develops a quantitative framework to evaluate ergonomics in the Elevate soft robotic suit for shoulder elevation, using motion capture and force sensing to infer interaction forces and deformations at the shoulder, torso, and upper arm. By defining measurable metrics such as shoulder pressure $P_i$, torso constriction, and cuff volume change, the work demonstrates that Elevate can transmit approximately $120 ext{ N}$ to the cuff while keeping shoulder pressures in the $69$–$85 ext{ kPa}$ range and maintaining small body constrictions ($\\leq 3\%$ torso, $\\leq 8\%$ upper arm) during dynamic loading up to ~70° elevation. The methodology relies on accessible sensing and geometry-based estimations rather than expensive pressure mats, enabling safer, repeatable benchmarking and informing ergonomic design choices for real-world deployment. The results serve as a benchmark for comparing soft exosuits and guide future studies involving diverse populations and higher assistive torques with improved control strategies.

Abstract

Soft robotic suits have the potential to rehabilitate, assist, and augment the human body. The low weight, cost, and minimal form-factor of these devices make them ideal for daily use by both healthy and impaired individuals. However, challenges associated with data-driven, user-specific, and comfort-first design of human-robot interfaces using soft materials limit their widespread translation and adoption. In this work, we present the quantitative evaluation of ergonomics and comfort of the Elevate suit - a cable driven soft robotic suit that assists shoulder elevation. Using a motion-capture system and force sensors, we measured the suit's ergonomics during assisted shoulder elevation up to 70 degrees. Two 4-hour sessions were conducted with one subject, involving transmitting cable tensions of up to 200N with no discomfort reported. We estimated that the pressure applied to the shoulder during assisted movements was within the range seen in a human grasp (approximately 69.1-85.1kPa), and estimated volumetric compression of <3% and <8% across the torso and upper arm, respectively. These results provide early validation of Elevate's ergonomic design in preparation for future studies with patient groups.

Quantifying Ergonomics in the Elevate Soft Robotic Suit

TL;DR

This study develops a quantitative framework to evaluate ergonomics in the Elevate soft robotic suit for shoulder elevation, using motion capture and force sensing to infer interaction forces and deformations at the shoulder, torso, and upper arm. By defining measurable metrics such as shoulder pressure , torso constriction, and cuff volume change, the work demonstrates that Elevate can transmit approximately to the cuff while keeping shoulder pressures in the – range and maintaining small body constrictions ( torso, upper arm) during dynamic loading up to ~70° elevation. The methodology relies on accessible sensing and geometry-based estimations rather than expensive pressure mats, enabling safer, repeatable benchmarking and informing ergonomic design choices for real-world deployment. The results serve as a benchmark for comparing soft exosuits and guide future studies involving diverse populations and higher assistive torques with improved control strategies.

Abstract

Soft robotic suits have the potential to rehabilitate, assist, and augment the human body. The low weight, cost, and minimal form-factor of these devices make them ideal for daily use by both healthy and impaired individuals. However, challenges associated with data-driven, user-specific, and comfort-first design of human-robot interfaces using soft materials limit their widespread translation and adoption. In this work, we present the quantitative evaluation of ergonomics and comfort of the Elevate suit - a cable driven soft robotic suit that assists shoulder elevation. Using a motion-capture system and force sensors, we measured the suit's ergonomics during assisted shoulder elevation up to 70 degrees. Two 4-hour sessions were conducted with one subject, involving transmitting cable tensions of up to 200N with no discomfort reported. We estimated that the pressure applied to the shoulder during assisted movements was within the range seen in a human grasp (approximately 69.1-85.1kPa), and estimated volumetric compression of <3% and <8% across the torso and upper arm, respectively. These results provide early validation of Elevate's ergonomic design in preparation for future studies with patient groups.
Paper Structure (14 sections, 4 equations, 3 figures)

This paper contains 14 sections, 4 equations, 3 figures.

Table of Contents

  1. Introduction
  2. The Elevate Suit
  3. Evaluation Methods
  4. Pressure and Force on the Shoulder
  5. Compression across the Torso
  6. Compression across the Upper Arm
  7. Experimental Setup and Protocol
  8. Experimental Setup
  9. Experimental Protocol
  10. Results and Discussion
  11. Pressure on the Shoulder
  12. Compression across the Torso and Upper Arm
  13. Limitations and Future Work
  14. Conclusion

Figures (3)

  • Figure 1: a) The Elevate suit. b-e) Estimation of suit-body interaction forces across multiple regions, derived from kinematic and geometric measurements obtained from reflective motion-capture markers, together with cable tension data from force sensors.
  • Figure 2: Study setup and protocol. a) Actuation and sensing: locations of the 13 body markers (green) and 17 suit markers (pink). Also shown are the two force sensors (outlined in blue) and motor. b) Motor torque command profile used (three of six trials shown). c) Schematic of the control, actuation, and sensing components used in the study.
  • Figure 3: Elevate - Body Interaction. a) Plots of pressure on the shoulder at the pulleys and force at the funnel, against input (proximal) cable tension from the motor. b) Plots of the percentage reduction in area estimated from the four torso markers vs shoulder angle and vs proximal cable tension. c) Plots of the percentage reduction in area estimated from the four cuff markers vs distal cable tension and vs proximal cable tension.