David Braun

News

Awards, grants, publications, patents, talks, and media coverage.

2026

  • Adjustable-equilibrium parallel elastic actuator (AE-PEA)Our paper, published in IEEE Robotics and Automation Letters, introduces an adjustable-equilibrium parallel elastic actuator that combines a direct-drive motor and a 3D-printed torsional spring with a small auxiliary motor for continuous equilibrium adjustment. The design integrates high torque control bandwidth, passive energy storage, shock mitigation, and equilibrium tuning in a single actuator.

2025

2024

2023

  • Workshop presenter at IEEE IROS 2023At the workshop “No More Slow Flexible Robots” at the IEEE/RSJ International Conference on Intelligent Robots and Systems in Detroit, Michigan, I will present “Compliant Actuators: Old Designs, New Directions,” on new concepts for compliant robot actuators that enhance robot agility.
  • Paper presentation at IEEE IROS 2023Our research introduces a new approximation to the spring-loaded inverted pendulum model of locomotion. The work was presented at the IEEE/RSJ International Conference on Intelligent Robots and Systems in Detroit, Michigan.
  • Paper published in IEEE RA-LOur paper “Variable Stiffness Floating Spring Leg: Performing Net-Zero Energy Cost Tasks Not Achievable Using Fixed Stiffness Springs” introduces a spring technology that is the subject of a pending patent application. The paper extends the century-old concept of energetically conservative fixed-stiffness springs to energetically conservative variable stiffness springs.
  • NSF Undergraduate Research SupportWe are grateful to have received NSF funding for an undergraduate summer research project focusing on optimizing spring designs for robotic applications. This generous funding will support one undergraduate student during a two-month summer research internship.
  • Invited talk by Professor Koushil SreenathProfessor Koushil Sreenath from UC Berkeley gave a talk at Vanderbilt on the control and learning of legged robot locomotion.
  • Session chair at IEEE ICRA 2023I am honored to serve as a Session Chair at the IEEE International Conference on Robotics and Automation in London, in a session on the dynamics and control of robots.
  • Paper presentation at IEEE ICRA 2023Our paper, “Data-driven Iterative Optimal Control for Switched Dynamical Systems,” published in IEEE Robotics and Automation Letters will be presented at the upcoming IEEE International Conference on Robotics and Automation in London.
  • Paper accepted in IEEE RA-LOur paper “Data-Driven Iterative Optimal Control for Switched Dynamical Systems” presents a method for reducing the simulation–reality gap with hardware-in-the-loop optimal control. The paper was accepted for publication in IEEE Robotics and Automation Letters.
  • Three papers accepted at IEEE ICRA 2023Three of our papers have been accepted for presentation at the IEEE International Conference on Robotics and Automation in London. The three papers introduce (1) a mechanical alternative to conventional batteries, offering a new approach to energy storage in robotics, (2) a human-driven variable stiffness spring that enables energy accumulation through the repetitive application of a small, constant force, and (3) a variable stiffness robot hip joint, designed to be adjusted by a human user, much like shifting gears on a bicycle. The three designs are the subject of pending patent applications.

2022

2021

  • Paper presentations at IEEE IROS 2021Two of our papers have been accepted for presentation at the IEEE/RSJ International Conference on Intelligent Robots and Systems 2021. The papers introduce Parallel Variable Stiffness Actuators, and a floating spring whose stiffness can be changed independently of the energy it stores.
  • Seeding Success GrantI am honored to receive the Seeding Success Grant from Vanderbilt University for the project, “Catapult Legs: Enhancing Human Physical Ability with Robotic Limbs.” This research explores variable stiffness designs to expand the potential of robotic systems and assistive technologies for humans.
  • Running shoe with programmable spring“Speed records have a strange, primal allure. If an angry elephant is chasing you, would you be fast enough to escape? What about a bear or a black mamba? In any of these cases, your chances are not very good unless you are a trained runner. Unless you had springs on your legs. What sounds like an idea from an animated series could actually work. That’s the conclusion of a new study conducted at Vanderbilt University.” — Die Welt, 31 March 2021 (translated from German). Read the full article (in German).
  • Paper presentation at IEEE ICRA 2021Our paper “Human Driven Compliant Transmission Mechanism” presents a mechanism that lets a person supply energy while the leg is in the air and release it when the foot is on the ground. It has been accepted for presentation at the IEEE International Conference on Robotics and Automation.

2020

2019

  • Associate editor at IEEE ICRA 2020I am honored to serve as an Associate Editor for the IEEE International Conference on Robotics and Automation 2020.
  • Paper published in IEEE T-ROOur paper, “Operational Space Control Under Actuation Constraints Using Strictly Convex Optimization,” has been published in IEEE Transactions on Robotics. This work extends the Operational Space Control formulation to systems with actuation constraints enabling enhanced control of robots.
  • Prototype variable-length leaf springWe successfully developed a prototype of a variable-length leaf-spring actuator capable of stiffness modulation with minimal energy consumption. The work, published in IEEE Transactions on Robotics, demonstrated the device’s potential in collaborative human–machine tasks. This work was achieved in collaboration with The Newman Laboratory for Biomechanics and Human Rehabilitation at MIT.
  • Hardware-in-the-loop optimal control published in IEEE T-ROOur paper “Hardware-in-the-Loop Iterative Optimal Feedback Control without Model-Based Future Prediction” was published in IEEE Transactions on Robotics. It introduces an optimal control method that does not rely on predictions from imperfect models, making it robust to modeling errors.
  • Dynamics and Control Lab moves from Singapore to the USAThe Dynamics and Control Laboratory transitioned from Singapore to the Advanced Robotics and Control Laboratory at Vanderbilt.
  • Control and design challenge at SUTDI led a week-long Control and Design Challenge at the Singapore University of Technology and Design, in which students worked on hands-on projects in robotics and engineering.
  • Hands-on research featured at SUTDOur hands-on research was featured on a billboard at the Singapore University of Technology and Design.
  • Paper published in IEEE TNSREOur paper “Enhancing Mobility with Quasi-Passive Variable Stiffness Exoskeletons” was published in IEEE Transactions on Neural Systems and Rehabilitation Engineering. It shows how a quasi-passive variable stiffness spring exoskeleton can decouple kinetic energy from limb deflection and force generation.

2018

  • Paper published in AutomaticaOur paper “Reinforcement Learning for a Class of Continuous-Time Input Constrained Optimal Control Problems” was published in Automatica. It extends reinforcement learning to a wider class of continuous-time optimal control problems with input constraints.
  • Positive-negative stiffness actuators published in IEEE T-ROOur paper “Positive-Negative Stiffness Actuators,” published in IEEE Transactions on Robotics, introduces an actuator that combines positive and negative stiffness spring mechanisms. The design enables open-loop stiffness modulation and equilibrium position control with a single motor.
  • Paper published in IEEE RA-LOur paper “Efficiently Computable Constrained Optimal Feedback Controllers” was published in IEEE Robotics and Automation Letters. It introduces two locally optimal feedback controllers designed for real-time implementation.
  • Invited talk at Vanderbilt UniversityI delivered an invited talk at Vanderbilt University on advances in robot control and design.
  • Robotics: Science and Systems review meetingI took part in the Robotics: Science and Systems review meeting at Cornell University. I am grateful to Professor Ani Hsieh from the University of Pennsylvania for our discussions, and for driving me from Philadelphia to Ithaca after our flight was canceled.
  • Invited talk at Carnegie Mellon UniversityIt was an honor to present an invited talk at Carnegie Mellon University, where I shared our work on the “Hardware-in-the-Loop Optimal Control Method.” The discussion focused on how this approach advances real-time optimal control in robotics.
  • Invited speaker at IEEE ICRA 2018 workshopI was an invited speaker at the IEEE International Conference on Robotics and Automation 2018 Workshop on Soft Robotics for Rehabilitation Applications: Design, Material, and Control. This workshop provided a platform to share and discuss advances in rehabilitation robotics.
  • Papers accepted at IEEE ICRA 2018Two of our papers have been accepted for presentation at the IEEE International Conference on Robotics and Automation 2018. The papers discuss the algorithmic design of compliant actuators and introduce a torsional leaf-spring actuator.

2017

  • Area chair for RSS 2018I am honored to serve as Area Chair for the 2018 Robotics: Science and Systems Conference, contributing to the organization of one of the leading robotics conferences.
  • MOE Tier 2 Research Fund awardedThis Tier 2 Academic Research Fund of the Singapore Ministry of Education supports research on optimal control in robotics, with the aim of energy-efficient control methods for robotic systems.
  • Invited speaker at IEEE ICRA 2017 workshopI am honored to be an invited speaker at the IEEE International Conference on Robotics and Automation 2017 Workshop on Recent Advances in Dynamics for Industrial Applications. My presentation focused on our research in advanced control methods for industrial robotics.
  • Papers accepted at IEEE ICRA 2017Two of our papers have been accepted for presentation at the IEEE International Conference on Robotics and Automation 2017. These papers detail the analytical design of compliant actuators and introduce a new negative stiffness actuator for robotic applications.

2016

  • Invited speaker at IEEE ICRA 2017 workshopI am an invited speaker at the upcoming IEEE International Conference on Robotics and Automation 2017 Workshop on The Mechanics of Human Locomotion and the Development of Wearable Robotic Systems. The workshop will bring together experts in biomechanics and robotics working on wearable technology.
  • Paper accepted in Physical Review EOur paper on Adaptive Optimal Parametric Excitation has been accepted for publication in Physical Review E published by the American Physical Society. This work introduces a data-driven self-tuning algorithm for achieving parametric resonance in bistable oscillators, with potential applications in signal amplification, energy harvesting, and robot control.
  • Seminar at the SUTD-MIT International Design CentreI delivered a seminar at the SUTD-MIT International Design Center in Singapore, where I presented our efforts to develop next-generation compliant robot actuators aimed at improving energy efficiency in robotic systems.
  • Associate editor for IEEE BioRob 2016I am honored to serve as an Associate Editor for the IEEE International Conference on Biomedical Robotics and Biomechatronics 2016, contributing to the review and organization of this conference.
  • Paper accepted at IEEE ICRA 2016Our paper on Energy-Efficient Impedance Modulation has been accepted for presentation at the IEEE International Conference on Robotics and Automation 2016. We are grateful for the collaboration with Professor Neville Hogan from MIT that made this work possible.

2015

  • Paper accepted in Physical Review LettersThe paper “Optimal Parametric Feedback Excitation of Nonlinear Oscillators,” accepted for publication in Physical Review Letters, shows how to excite an oscillator optimally by periodically varying a system parameter, without a model of the system. The principle applies to energy-efficient control of physical systems across domains and scales.
  • Two research grants received for robot exoskeletonsWe have received two research grants from the Singaporean Ministry of Education and the Changi General Hospital to support our work on robot exoskeletons. These grants will enable us to advance research in assistive wearable robotics.
  • Invited talk by Professor Thomas PeacockProfessor Thomas Peacock from MIT delivered an invited talk at the Singapore University of Technology and Design on fluid dynamics. I am grateful for his visit and our discussions on non-intuitive dynamics problems.
  • Invited talk at Asian Robotics WeekI delivered an invited talk at the 2015 Asian Robotics Week held at Marina Bay Sands in Singapore. This event brought together local stakeholders in the area of robotics and highlighted regional and international advances in robotics research.
  • Invited talk by Professor Michael GoldfarbWe had the pleasure of welcoming Professor Michael Goldfarb from Vanderbilt University, who delivered an invited talk at the Singapore University of Technology and Design on the latest developments in human rehabilitation technologies.
  • Scientific program co-chair for IEEE ICORR 2015I am honored to serve as the Scientific Program Co-Chair for the IEEE International Conference on Rehabilitation Robotics 2015, contributing to the program’s organization and facilitating research discussions.
  • Exhibition at the ArtScience Museum in SingaporeOur energy-efficient compliant actuator is now on display at the ArtScience Museum in Singapore, in an exhibition that brings together technology and art to introduce the public to robotics research.

2014