Accepted or Published Works
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Lekan Molu.
July 2025 Published
Abstract
Supplementary material accompanying LevelSetPy, providing extended benchmark evaluations, numerical examples, and performance comparisons against MATLAB toolbox baselines on Hamilton-Jacobi reachability problems in up to six dimensions.
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Lekan Molu.
March 2025 Published
Abstract
LevelSetPy is a Python package for numerically solving hyperbolic Hamilton-Jacobi PDEs that arise in reachability analysis and level set methods. Leveraging JAX-based GPU acceleration, it achieves order-of-magnitude speedups over the standard MATLAB toolbox while providing a modern, differentiable programming interface for robotics and control researchers.
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Lekan Molu.
June 2025 Published
Abstract
We present a singularly-perturbed backstepping controller for whole-body strain regulation in multi-section continuum robots modeled by discrete Cosserat rods. The composite fast-slow design decouples the bending and shear strain dynamics, achieving convergence guarantees and superior transient performance compared to monolithic control laws.
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Lekan Molu.
December 2024 Published
Abstract
This paper introduces LevelSetPy, a Python-native reimplementation of the Hamilton-Jacobi reachability toolbox with GPU support via JAX. We demonstrate its correctness and efficiency on canonical pursuit-evasion games and high-dimensional reachability problems relevant to autonomous systems.
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Lekan Molu and Shaoru Chen.
December 2024 Published
Abstract
We analyze the structural (controllability, observability, and passivity) properties of multi-section soft robots modeled by discrete Cosserat rod theory. Exploiting these properties, we design an energy-based controller with provable stability guarantees and validate it in simulation on a three-section planar manipulator.
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Shaoru Chen, Lekan Molu, and Mahyar Fazlyab.
May 2024 Published
Abstract
We propose a counterexample-guided training procedure for neural network barrier functions that incorporates a formal verifier in the training loop. The algorithm terminates with a certificate of correctness and significantly reduces the barrier function training time compared to purely adversarial approaches.
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Anurag Koul, Shivakanth Sujit, Shaoru Chen, Ben Evans, Lili Wu, Lekan Molu, Byron Xu, Rajan Chari, Riashat Islam, Raihan Seraj, Yonathan Efroni, Miroslav Dudík, John Langford, Alex Lamb
September 2023 Published
Abstract
PCLAST learns a continuous latent state space from high-dimensional observations in which planning with simple interpolation is provably correct. By optimizing for topological planability rather than reconstruction fidelity, the learned representations support reliable goal-conditioned planning in complex visual environments without environment-specific reward engineering.
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Lekan Molu.
July 2023 Published
Abstract
We formulate and solve a continuous-time mixed H2/H-infinity reinforcement learning problem for output-feedback control synthesis without a known system model. The algorithm iterates policy evaluation and improvement steps on data collected from the system, converging to an optimal robust policy under disturbance attenuation constraints.
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Leilei Cui and Lekan Molu.
April 2023 Published
Abstract
We study robust policy optimization in continuous-time stochastic systems under the mixed H2/H-infinity performance criterion. Combining stochastic differential equation theory with modern policy gradient methods, we derive convergence rates and demonstrate improved robustness to model uncertainty in uncertain dynamical systems arising in robotics and medical automation.
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Alex Lamb, Riashat Islam, Yonathan Efroni, Aniket Didolkar, Dipendra Misra, Dylan Foster, Lekan Molu, Rajan Chari, Akshay Krishnamurthy, John Langford.
December 2022 Published
Abstract
We prove that multi-step inverse dynamics models recover controllable latent state representations with provable guarantees under a rich-observation MDP assumption. The theoretical analysis resolves an open question on when self-supervised representation learning methods succeed for downstream control tasks.
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Tengyang Xie, Akanksha Saran, Dylan J Foster, Lekan Molu, Ida Momennejad, Nan Jiang, Paul Mineiro, and John Langford.
May 2022 Published
Abstract
We extend interaction-grounded learning (IGL) to settings where actions affect the feedback signal itself. By incorporating action-inclusive feedback into the IGL framework, we derive provably efficient algorithms for learning reward-free representations and policies in partially observable environments, with applications to healthcare decision support.
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Olalekan Ogunmolu, Xinmin Liu, Nick Gans, and Rodney Wiersma.
May 2020 Published Video
Abstract
We present the mechanical design, kinematic modeling, and experimental validation of a soft pneumatic robot that immobilizes a patient's head during frameless MRI-guided radiation therapy. The mechanism compensates for involuntary motion in real time using a vision-based feedback loop, reducing positioning error to sub-millimeter accuracy.
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Olalekan Ogunmolu
May 2019 Published
Abstract
This dissertation develops a multi-degree-of-freedom soft robotic system for real-time patient positioning and beam orientation selection in intensity-modulated radiation therapy (IMRT). Contributions include continuum robot modeling via Cosserat rod theory, neuro-adaptive control for 6-DOF pose correction, deep reinforcement learning for beam angle optimization, and clinical validation on a CyberKnife platform.
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Azar Sadeghnejad Barkousaraie, Olalekan Ogunmolu, Steve Jiang, and Dan Nguyen.
December 2019 Published
Abstract
We present a convolutional neural network that predicts near-optimal beam orientations for IMRT prostate cancer treatment plans in under one second, matching the quality of column-generation-based optimization while reducing planning time by two orders of magnitude.
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Olalekan Ogunmolu, Michael Folkerts, Dan Nguyen, and Steve Jiang.
2019 Published
Abstract
We frame beam orientation optimization (BOO) in radiation therapy as a sequential decision problem and train a deep neural network policy using imitation learning from a column-generation solver. The learned policy selects coplanar and non-coplanar beam configurations that rival expert-optimized plans while running in real time.
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Olalekan Ogunmolu, Nick Gans, and Tyler Summers.
Madrid 2018 Published
Abstract
We present a minimax iterative dynamic game algorithm for robust nonlinear robot control under adversarial perturbations. The method frames the control problem as a two-player zero-sum game and computes feedback policies via saddle-point iterations on the Hamilton-Jacobi-Isaacs equation, achieving superior robustness on a 6-DOF arm tracking task compared to standard optimal control baselines.
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Olalekan Ogunmolu, Adwait Kulkarn, Yonas Tadesse, Xuejun Gu, Steve Jiang, and Nick Gans.
Vancouver, BC 2017 Published
Abstract
Soft-NeuroAdapt is a three-degree-of-freedom soft actuator system coupled with a neuro-adaptive controller that corrects patient head pose in real time for maskless frameless cancer radiotherapy. The neural adaptive law compensates for actuator and tissue nonlinearities, achieving sub-millimeter positioning accuracy without requiring a rigid fixation mask.
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Yara Almubarak, Joshi Aniket, Olalekan Ogunmolu, Xuejun Gu, Steve Jiang, Nicholas Gans, and Yonas Tadesse
Denver, CO, U.S.A. March 2018 Published
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Olalekan Ogunmolu, Xuejun Gu, Steve Jiang, and Nick Gans.
Fort-Worth, Texas, August 2016 Published
Abstract
We present a vision-based closed-loop control architecture for a pneumatic soft robot that positions a patient's head during maskless cancer radiotherapy. A model-free adaptive controller uses real-time pose feedback from a stereo camera to drive positioning error below the clinical tolerance of 1 mm.
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Olalekan Ogunmolu, Xuejun Gu, Steve Jiang, and Nick Gans.
Gothenburg, Sweden, August 2015 Published
Abstract
We describe the first real-time soft-robotic patient positioning system for maskless head-and-neck cancer radiotherapy, demonstrating a proof-of-concept platform that uses pneumatic actuators and image-based feedback to maintain sub-millimeter positioning accuracy during treatment fractions.
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Azar Sadeghnejad Barkousaraie, Olalekan Ogunmolu, Steve Jiang, and Dan Nguyen.
Montreal, CA. June 2019 Published

  Submitted Works
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Visuomotor Diffusion Policies in Infinite Dimensions
Lekan Molu.
Transactions on Robotics
2026
Abstract
Vision-conditioned diffusion models denoise probabilistic models of infinite-dimensional stochastic processes in finite-dimensional algorithmic settings. We frame visuomotor policy recovery as an inverse PDE stochastic diffusion optimization in continuous-time and continuous states, prescribing an ideal solution within the problem's natural infinite-dimensional fabric. Characterizing the underlying structure as an inverse stochastic optimal control problem, we provide learning machinery for consistent controllable point-to-point generative sampling that enables downstream imitation learning and behavior cloning in robot behavior models, with demonstrated improvements on embodied physical systems.
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Approximate HJ Reachability via Importance Sampling
Lekan Molu.
2026
Abstract
Computing safe reachable sets in verification settings via viscous Hamilton-Jacobi (HJ) PDEs requires grid discretization of phase space, incurring exponential memory costs. Linearizing the HJ PDE, we extend solutions to backward reach tubes and reach-avoid tubes, and cast safe-set recovery as integration of a Gaussian process that approximates the HJ variational PDE. The result is a storage-free, GPU-friendly method for resolving safe reachable sets without the memory burden of grid discretization.
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Promise Ekpo, Angelique Taylor, and Lekan Molu.
November 2025
Abstract
We formulate trauma resuscitation as a multi-agent control problem and propose a generalized Nash equilibrium-seeking policy that coordinates multiple clinical agents under resource constraints, improving patient outcomes while satisfying safety and fairness requirements.
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Lekan Molu, Abulikemu Abuduweili, Dean Fortier, Jun Takamatsu, Elise van der Pol, Naoki Wake, and Katsu Ikeuchi
Science Robotics
April 2025
Abstract
We present a universal collision-free planner for open-embodiment robots that combines compact implicit scene representations with memory-efficient incremental occupancy mapping. The method generalizes across robot morphologies without retraining and achieves real-time planning in cluttered, partially observed environments.
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Others and Lekan Molu
June 2025
Abstract
We develop a theoretical framework for multi-agent proximal policy optimization that simultaneously provides convergence guarantees, robustness certificates, constraint satisfaction for safety, and convergence to generalized Nash equilibria in mixed cooperative-competitive settings.
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Haoxiang You, Lekan Molu, and Ian Abraham
March 2025
Abstract
We investigate whether value function approximation via Bellman residual minimization is sufficient for stable and optimal control. Examining failure modes in continuous-time systems, we identify conditions under which the Bellman equation is necessary but not sufficient, and propose an augmented PSD-constrained network architecture that recovers stability guarantees.

  Technical Reports
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Olalekan Ogunmolu, Nick Gans, and Tyler Summers.
2017 Technical Report
Abstract
We develop a deep reinforcement learning algorithm for zero-sum two-player games that is robust to function approximation errors and sparse rewards. The approach uses adversarial training and minimax Q-learning, achieving stronger worst-case guarantees than standard DRL baselines on robotic manipulation and locomotion tasks.
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Olalekan Ogunmolu, Xuejun Gu, Steve Jiang, and Nick Gans.
2016 Technical Report
Abstract
We identify nonlinear dynamical systems using deep recurrent neural networks trained end-to-end on input-output data. Applied to soft-robot dynamics identification, the approach outperforms classical system identification methods and provides a differentiable model suitable for model-based control.
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Towards Real-Time Motion Compensation in Radio-Transparent Robotic Radiation Therapy
Olalekan Ogunmolu
Technical Report
2019 Technical Report

  Presentations
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Tengyang Xie, Akanksha Saran, Dylan J Foster, Lekan Molu, Ida Momennejad, Nan Jiang, Paul Mineiro, and John Langford.
May 2022 Oral
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A Real-Time Patient Head Motion Correction Mechanism for MRI-Linac Systems
Olalekan Ogunmolu, and Rodney Wiersma
Oral Presentation at Medical Physics 47 (6)(AAPM) E328-E328. Online only publication in the Medical Physics Journal, Annual Meeting of the American Association of Physicists in Medicine (AAPM)
May 2021 Oral
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Towards Closed-Loop Control Head Motion Correction with Soft Actuators in MRI-LINAC Systems
Olalekan Ogunmolu, and Rodney Wiersma
Oral Presentation at Medical Physics (AAPM) 46 (6). Online only publication in the Medical Physics Journal, Annual Meeting of the American Association of Physicists in Medicine (AAPM)
May 2020 Oral
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Lagrangian Properties and Control of Soft Robots Modeled with Discrete Cosserat Rods.
Lekan Molu, Shaoru Chen, and Audrey Sedal
Yale University, New Haven, Connecticut. November 2023 Abstract
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Composite Fast-Slow Backstepping Design for Nonlinear Singularly Perturbed Newton-Euler Dynamics: Application to Soft Robots.
Lekan Molu
Yale University, New Haven, Connecticut. November 2023 Abstract
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PcLast: Discovering Plannable Continuous Latent States.
Anurag Koul, Shivakanth Sujit, Shaoru Chen, Ben Evans, Lili Wu, Lekan Molu, Byron Xu, Rajan Chari, Riashat Islam, Raihan Seraj, Yonathan Efroni, Miroslav Dudik, John Langford, Alex Lamb
Yale University, New Haven, Connecticut. November 2023 Abstract
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A Reinforcement Learning Application of Guided Monte Carlo Tree Search Algorithm for Beam Orientation Selection in Radiation Therapy
Azar Sadeghnejad Barkousaraie, Olalekan Ogunmolu, Steve Jiang, and Dan Nguyen
Oral Presentation at Medical Physics (AAPM) 46 (6), E236-E236. Proceedings in the 60th Annual Meeting of the American Association of Physicists in Medicine (AAPM), San Antonio, TX.
San Antonio, TX, July 2019. Oral
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An Approximate Policy Iteration Scheme for Beam Orientation Selection in Radiation Therapy
Olalekan Ogunmolu, Azar Sadeghnejad Barkousaraie, Nick Gans, Steve Jiang, and Dan Nguyen
Oral Presentation at Medical Physics (AAPM) 46 (6), E386-E386. Online only publication in the Medical Physics Journal, Proceedings in the 60th Annual Meeting of the American Association of Physicists in Medicine (AAPM), San Antonio, TX.
San Antonio, TX, July 2019. Oral
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Automating Beam Orientation Optimization for IMRT Treatment Planning: A Deep Reinforcement Learning Approach
Olalekan Ogunmolu, Dan Nguyen, Chenyang Shen, Xun Jia, Weiguo Lu, and Nick Gans,
60th Annual Meeting of the American Association of Physicists in Medicine (AAPM), Nashville, TN
July 2018 Abstract
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A Real-Time Patient Head Motion Correction Mechanism for MRI-Linac Systems
Olalekan Ogunmolu, and Rodney Wiersma.
June 2020 Oral
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A Motion-Planner for Robot Head Motion Correction in Stereotactic Radiosurgery
Olalekan Ogunmolu, Xinmin Liu, and Rodney Wiersma.
June 2020 Abstract
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Minimax Iterative Dynamic Game: Application to Nonlinear Robot Control Tasks
Olalekan Ogunmolu, Nick Gans, and Tyler Summers
Brisbane, Australia, May 2018 Abstract
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Minimax Iterative Dynamic Game: Application to Nonlinear Robot Control Tasks
Olalekan Ogunmolu, Nick Gans, and Tyler Summers
Madrid, Spain. October 2018 Abstract
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Robustness Margins and Robust Guided Policy Search for Deep Reinforcement Learning
Tyler Summers, Olalekan Ogunmolu, and Nick Gans
IROS 2017 Abstract Only Track
Vancouver, BC, Canada. September 2017 Abstract