I’m excited to share that our paper, “Compliant Explicit Reference Governor for Contact Friendly Robotic Manipulators”, has been accepted to the IFAC World Congress!

This work was led jointly with Yaashia Gautam (equal contribution), in collaboration with Adhitya Mohan, Nataliya Nechyporenko, Alessandro Roncone, and Marco M. Nicotra.

Paper Summary

Traditional motion planning treats contact with the environment as something to be avoided. But modern manipulation — wiping a surface, pushing an object, leaning against a wall — needs contact to be treated as a resource, not a hazard. CERG is a modular safety filter that sits between any high-level planner and any low-level controller and enables robots to:

  • Freely move when no contact is required, with no performance penalty.
  • Safely engage in contact, by bounding the total mechanical energy (kinetic + potential) of the closed-loop system below a user-defined Emax.
  • Smoothly transition between free motion and contact without rewriting the controller or solving a custom MPC at runtime.

Under the hood, CERG extends the Explicit Reference Governor framework with:

  1. A Compliant Dynamic Safety Margin that handles disjunctive (OR-type) constraints — “avoid the surface or contact it with bounded energy.”
  2. A Soft Navigation Field that lets the virtual reference penetrate the constraint boundary, which is what produces the compliant contact behavior.
  3. Provable guarantees on constraint satisfaction and asymptotic stability — without redesigning the underlying controller.

Key Results

We validated CERG on a progression of platforms:

  • A 2-link planar arm in MATLAB, showing CERG reduces interaction forces under both joint-space and end-effector control formulations.
  • A 7-DoF Franka Emika Panda in Drake, with the full Compliant Contact Model, where CERG adheres to Emax during contact while matching the standard ERG’s free-motion energy profile.
  • Two real-world Franka tasks:
    • Whiteboard wiping: CERG enforced three different Emax values during contact; standard ERG and Cartesian impedance control both violated constraints.
    • Jenga tower pushing: CERG completed the task without toppling the tower, while ERG over-energized the contact and impedance control either violated joint-velocity limits or toppled the stack.

Why It Matters

CERG offers a drop-in safety layer for any robot with a legacy controller, providing principled guarantees for contact-rich manipulation — exactly the regime where most physical-interaction tasks (assembly, surface tracing, gentle pushing, human–robot contact) live. It’s a step toward robots that can confidently touch the world without breaking it, or themselves.

Thanks to my co-authors and to the NSF and NASA programs supporting this work. Looking forward to presenting in Busan!