Shihao Cheng
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Research

Continuous Impedance Control for Wearable Locomotion

A phase-variable impedance controller that continuously blends walking and stair behavior during stance, extending smooth transition control from prosthesis motion to prosthesis support. Plainly: this focuses on how stiff or supportive the prosthesis should feel while the user is loading it during a transition.

IEEE TNSRE 2026 Phase-Variable Control Impedance Control Walk–Stair Transition Powered Prosthesis
Watch Video TNSRE 2026 Paper
Related: Prior Work (TNSRE 2024) →
Loop demo of continuous walk-stair transition behavior with phase-variable impedance control.
Problem & Contribution

Smooth swing motion isn't enough — during stance the robot must also provide the right support, so this extends continuous transition control into impedance behavior during weight-bearing.

My Role

I contributed to extending continuous transition control from kinematic trajectories to stance-phase impedance behavior for powered knee-ankle prostheses.

Challenge

Transitioning swing kinematics alone leaves stance-phase impedance switching abrupt during walk–stair transitions.

Contribution

Stance-phase support adaptation during walk–stair transitions in a powered prosthesis.

Ph.D. research conducted in the LocoLab at the University of Michigan, advised by Prof. Robert D. Gregg.

How It Extends
  1. 1 Kinematic Transition Control Prior work blends walking and stair motion continuously (TNSRE 2024).
  2. 2 Stance Impedance Blending The same phase variable now blends knee–ankle impedance during stance.
  3. 3 Adaptive Support The prosthesis provides the right support as load shifts through the transition.
Evidence
Stance Support Adaptation
Stance Phase
Variable-Stair Validation
Human Subjects
Builds on TNSRE 2024
Extension

Figures

Overview of the continuous impedance transition framework for walk-stair prosthesis control (TNSRE 2026)
Three-panel workflow showing steady-state continuous impedance models, interpolation between models, and variable-incline walk-stair transition execution. Adapted from Cortino et al., IEEE TNSRE 2026. © 2026 IEEE.
Continuous impedance transition results across walk-stair conditions (TNSRE 2026)
Knee- and ankle-moment trajectories across walk-to-stair-ascent, stair-ascent-to-walk, walk-to-stair-descent, and stair-descent-to-walk transitions, comparing able-bodied data with continuous and discrete control strategies. Adapted from Cortino et al., IEEE TNSRE 2026. © 2026 IEEE.

Technical Stack

Impedance Control Stance-Phase Support Phase Variable Continuous Transitions Weight-Bearing Control Powered Prosthesis Platform
More Related Work
View all projects →
tnsre2024_exp Control Phase-Variable Control for Continuous Locomotion Transitions Walk–stair transitions are brittle when a controller depends on one perfect switching moment; making them smooth and timing-robust is one of the strongest results of my Ph.D. work. View Project → Replay-constrained sim-to-real personalization concept diagram Personalization Replay-Constrained Sim-to-Real Personalization for Prosthesis Control A prosthesis never walks alone — it is coupled to a human whose neuromuscular response is hard to model. Rather than simulate the person, this work replays recorded user motion while simulating the device, so risky high-dimensional impedance strategies can be screened and ranked before any real-user trial. View Project →
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