Embedded Control|2026

FlexStrong Closed-Loop Grip Assistance System

A wearable assistive system that uses electrical muscle stimulation, sensor feedback, and embedded control logic to augment grip strength in real time.

Embedded CSTM32Flex sensorsFSRsTENS controlX9C103SOLEDFeedback controlState machines

Project Overview

Built the main embedded program and state machine around the sequence IDLE, PULSE, CONTROL, COOLDOWN, and STOP so the system could manage stimulation behavior explicitly instead of relying on ad hoc logic.

Implemented flex sensor processing, grip detection logic, and FSR-based force feedback to compare measured force against a target and adjust stimulation intensity in real time.

Integrated the digital potentiometer, display output, and safety-critical behavior including emergency shutoff, controlled ramp-up, and default intensity limits.

Used a PI-style control structure to explore the tradeoff between responsiveness, stability, and user comfort in a closed-loop assistive device.

Technical Details

STM32 microcontroller programmed in embedded C.
Flex sensors used for grip intent detection and FSRs used for force feedback.
TENS output controlled through an X9C103S digital potentiometer.
OLED display used for system state and live feedback.
Closed-loop update rate of roughly 50 Hz.

Engineering Challenges

Filtering noisy sensor readings and choosing grip detection thresholds that were reliable in practice.
Designing PI-style control that stayed responsive without overshooting or oscillating.
Handling quantized actuator control through integer potentiometer steps.
Building in safe shutdown and controlled ramp-up behavior for a system that directly affects the user.