# Towards Clinical Trial Readiness: Optimization of a Parallel Robot for Lower Limb Rehabilitation

## TL;DR

This paper describes the optimization of a robotic system for lower limb rehabilitation, using feedback to improve safety and usability for future clinical trials.

## Contribution

The novel use of fuzzy logic to convert subjective feedback into objective design improvements for a rehabilitation robot.

## Key findings

- Safety, torque capacity, and adaptability were identified as key areas needing improvement.
- Mechanical refinements improved user comfort and perceived safety.
- The optimized system shows improved readiness for clinical evaluation.

## Abstract

This study presents the clinical trial readiness and optimization of a parallel robotic system developed for early-stage lower limb rehabilitation of bedridden patients using feedback from healthy users and clinicians. The system combines a parallel hip–knee mechanism with a Bowden cable-driven ankle module, both actuated by servomotors and controlled through a PLC platform. Experimental tests were performed in laboratory conditions with twenty healthy participants (aged 25–45) and ten clinicians, focusing on safety, ergonomics, clinical usability, and comfort through structured questionnaires. The responses were quantified and analyzed using a Mamdani-type fuzzy logic model, allowing subjective feedback to be converted into objective redesign priorities. Safety, torque capacity, and adaptability emerged as the key areas that need improvement. Subsequent mechanical and structural refinements resulted in substantial gains in user comfort, perceived safety, and clinician-reported applicability. The optimized robotic system demonstrates enhanced functionality and improved readiness for clinical evaluation, highlighting the benefit of incorporating fuzzy logic-based feedback into the development of rehabilitation robots.