[Paper Review] SUPER-MAN: SUPERnumerary Robotic Bodies for Physical Assistance in HuMAN-Robot Conjoined Actions

Alberto Giammarino, Juan M. Gandarías+4 more|arXiv (Cornell University)|Jan 17, 2022

Prosthetics and Rehabilitation Robotics4 citations

TL;DR

This paper introduces SUPER-MAN, a mobile supernumerary robotic system that enhances human-robot collaboration in industrial tasks through an admittance-based interface and whole-body control. The framework enables two implementations—MOCA-MAN and Kairos-MAN—demonstrating improved task performance and reduced user workload in physical assistance scenarios, validated via user studies and NASA-TLX assessments.

ABSTRACT

This paper presents a mobile supernumerary robotic approach to physical assistance in human-robot conjoined actions. The study starts with a description of the SUPER-MAN concept. The idea is to develop and utilize mobile collaborative systems that can follow human loco-manipulation commands to perform industrial tasks through three main components: i) an admittance-type interface, ii) a human-robot interaction controller, and iii) a supernumerary robotic body. Next, we present two possible implementations within the framework from theoretical and hardware perspectives. The first system is called MOCA-MAN and comprises a redundant torque-controlled robotic arm and an omnidirectional mobile platform. The second one is called Kairos-MAN, formed by a high-payload 6-DoF velocity-controlled robotic arm and an omnidirectional mobile platform. The systems share the same admittance interface, through which user wrenches are translated to loco-manipulation commands generated by whole-body controllers of each system. Besides, a thorough user study with multiple and cross-gender subjects is presented to reveal the quantitative performance of the two systems in effort-demanding and dexterous tasks. Moreover, we provide qualitative results from the NASA-TLX questionnaire to demonstrate the SUPER-MAN approach's potential and its acceptability from the users' viewpoint.

Motivation & Objective

• Address the limitations of wearable assistive devices like exoskeletons and supernumerary robotic limbs, which suffer from discomfort, mobility restrictions, and dependency on human coupling.
• Overcome the underutilization of collaborative robots (Cobots) by enabling direct, physical human-robot interaction in dynamic, task-oriented environments.
• Develop a floating-base robotic system that acts as a supernumerary body, extending human capabilities without physical attachment, thereby improving task efficiency and user comfort.
• Enable seamless human-robot conjoined loco-manipulation through intuitive force-based control and adaptive whole-body motion planning.
• Validate the system’s effectiveness through quantitative performance metrics and user perception data from cross-gender subject studies.

Proposed method

• Implement a mobile supernumerary robotic framework (SUPER-MAN) using an admittance-type interface to translate human-generated wrenches into loco-manipulation commands.
• Design two distinct robotic platforms: MOCA-MAN (redundant torque-controlled arm on omni-directional base) and Kairos-MAN (high-payload 6-DoF velocity-controlled arm on omni-directional base), both sharing the same interface and control architecture.
• Employ whole-body controllers with hierarchical task prioritization, using Cartesian stiffness and damping matrices to balance compliance, tracking accuracy, and stability.
• Apply null-space optimization to decouple base and arm motions, ensuring minimal interference during manipulation and locomotion modes.
• Use a virtual model-based control strategy with virtual mass and damping to regulate mobile base dynamics and ensure smooth, stable motion.
• Tune admittance controller parameters (mass and damping matrices) to balance controllability, transparency, and user effort during interaction.

Experimental results

Research questions

• RQ1 Can a mobile supernumerary robotic system effectively reduce physical workload in human-robot conjoined industrial tasks without requiring wearable attachment?
• RQ2 How does the performance of a mobile supernumerary robot compare to traditional assistive devices in terms of task accuracy and user effort?
• RQ3 To what extent does the admittance-based interface enable intuitive, force-guided control of mobile manipulators in dynamic human-robot collaboration?
• RQ4 How do different robotic configurations (MOCA-MAN vs. Kairos-MAN) affect task performance and user perception in dexterous and effort-demanding operations?
• RQ5 What is the user experience and perceived workload when interacting with a mobile supernumerary robotic body in real-world industrial tasks?

Key findings

• The SUPER-MAN framework significantly reduces user workload in physical assistance tasks, as evidenced by NASA-TLX scores indicating lower mental and physical demand compared to unassisted operation.
• MOCA-MAN and Kairos-MAN demonstrated improved task performance in both dexterous and effort-demanding operations, with Kairos-MAN showing superior performance in high-payload scenarios due to its 6-DoF velocity-controlled arm.
• User studies revealed that subjects achieved higher task completion accuracy and lower perceived effort when assisted by the supernumerary robotic body, particularly in repetitive and high-force tasks.
• The admittance interface enabled intuitive control with minimal learning curve, as shown by consistent performance across subjects of different genders and physical profiles.
• The whole-body controller with hierarchical task prioritization successfully decoupled base and arm motions, minimizing unintended base movements during manipulation and ensuring stable locomotion.
• Parameter tuning of the admittance and whole-body controllers—particularly the damping and stiffness matrices—resulted in stable, compliant, and responsive robot behavior under varying task conditions.