Publications
Welcome to my collection of robotics research publications. My work focuses on mechanically adaptive robotics, optimal control, actuator design, and the theory of human performance augmentation—pushing the boundaries of intelligent systems and automation. Through peer-reviewed articles, conference papers, and patents, I share insights into the challenges and breakthroughs driving robot autonomy and adaptive technology. Explore my latest research and discover how these innovations are shaping the future of robotics.
Design and Control of a Parallel Elastic Actuator with Adjustable Equilibrium Position
Yixi Chen, Evangelos Chatziandreou, Chase Mathews, Beau Johnson, and David J. Braun, Design of a Parallel Elastic Actuator with Continuously Adjustable Equilibrium Position, IEEE Robotics and Automation Letters, vol. 11, no. 6, pp. 6512-6519, 2026. We present an adjustable-equilibrium parallel elastic actuator (AE-PEA) that combines…
Learning Finite-Horizon Optimal Control with Unknown Control-Affine Dynamics
Y. Chen, Y. Li and D.J. Braun, Learning Finite-Horizon Optimal Control with Unknown Control-Affine Dynamics, Systems & Control Letters, vol. 203, no. 106161, 2025. This paper introduces a model-free method for designing optimal controllers over a fixed time horizon. Instead of relying on a detailed…
Energy Minimization using Custom-Designed Magnetic-Spring Actuators
Y. Y. Fu, A.U. Kilic and D.J. Braun, Energy Minimization using Custom-Designed Magnetic-Spring Actuators, IEEE International Conference on Intelligent Robots and Systems, pp. 3534-3539, October 14 – 18, Abu Dhabi, United Arab Emirates, 2024. This paper presents a new actuator design that integrates a conventional…
A Novel Approximation for the Spring Loaded Inverted Pendulum Model of Locomotion
A.U. Kilic and D.J. Braun, A Novel Approximation for the Spring-Loaded Inverted Pendulum Model of Locomotion, IEEE International Conference on Intelligent Robots and Systems, pp. 4315-4321, October 1 – 5, Detroit, MI, USA, 2023. This paper introduces a new analytical approximation of the Spring-Loaded Inverted…
Human Adaptable Variable Stiffness Springs
D. Braun, C. W. Mathews, Human Adaptable Variable Stiffness Springs, US Patent Application 18/226,204, 2023. This patent describes variable stiffness spring mechanisms designed for human-centered applications. One design integrates a torsional spring with a self-locking mechanism and auxiliary spring, allowing stiffness to be adjusted at…
Variable Stiffness Floating Spring Leg: Performing net-zero energy cost tasks not achievable using fixed stiffness springs
S.Y. Kim and D.J. Braun, Variable Stiffness Floating Spring Leg: Performing net-zero energy cost tasks not achievable using fixed stiffness springs, IEEE Robotics and Automation Letters, vol. 8, no. 9, pp. 5400-5407, 2023. This paper introduces a new variable stiffness spring design that combines force amplification…
Controllable Mechanical-domain Energy Accumulators
S.Y. Kim and D.J. Braun, Controllable Mechanical-domain Energy Accumulators, IEEE International Conference on Robotics and Automation, London, United Kingdom, pp. 7359-7364, 2023. This paper presents a novel lockable compression spring that can store and release mechanical energy with high efficiency and precise control. The design uses…
Design of a Variable Stiffness Spring with Human-Selectable Stiffness
C. Mathews and D.J. Braun, Design of a Variable Stiffness Spring with Human-Selectable Stiffness, IEEE International Conference on Robotics and Automation, London, United Kingdom, pp. 7385-7390, 2023. This paper introduces a variable stiffness spring that allows users to manually adjust stiffness, similar to changing gears on…
Novel Spring Mechanism Enables Iterative Energy Accumulation under Force and Deformation Constraints
C. Dempsey and D.J. Braun, Novel Spring Mechanism Enables Iterative Energy Accumulation under Force and Deformation Constraints, IEEE International Conference on Robotics and Automation, London, United Kingdom, pp. 7391-7397, 2023. This paper introduces a floating spring mechanism that allows energy to be accumulated iteratively across multiple…
Method and Apparatus for Human Augmentation and Robot Actuation
D. Braun, C. W. Mathews, Method and apparatus for human augmentation and robot actuation, US Patent 17/872,164, 2022. This patent discloses a Parallel Variable Stiffness Actuator (PVSA) that combines a direct-drive motor with a variable stiffness spring arranged in parallel. The design allows the motor…
Variable Stiffness Mechanisms for low Energy Cost Stiffness Modulation
D. Braun, S. Kim, Variable Stiffness Mechanisms for low Energy Cost Stiffness Modulation, US Patent Application 17/506,164, 2021. This patent describes a variable-stiffness floating spring mechanism that can change stiffness without altering the energy stored in the spring. The design allows amplification of human output…
Method and Apparatus for Augmented Locomotion
D. Braun, A. Sutrisno, and T. Zhang, Method and Apparatus for Augmented Locomotion, US Patent 17/127,080, 2020. This patent discloses apparatuses for augmenting human locomotion using variable stiffness mechanisms that selectively store and release energy generated by human movement. By capturing and releasing this energy…