Learning from Demonstrations Meets Symbolic Control - A Supervisory Control Architecture for Formal Certification of Learned Motion
Authors: Ashok Kumar, Mahathi Anand, Angela P. Schoellig, Abdalla Swikir
Organizations: Mohamed bin Zayed University of Artificial Intelligence, Abu Dhabi, UAE. · Learning Systems and Robotics Lab, Technical University of Munich, Germany.
Dynamical system (DS)-based learning from demonstration generates flexible robot motions, but existing guarantees rely on certificate generation to obtain formal guarantees of safety and goal convergence. We propose a symbolic supervisory control architecture that automatically generates a fail-safe backup plan, certifying safety, reachability, and actuator feasibility directly from the robot's dynamics, independent of the learned DS. A nominal controller tracks the learned DS, while the supervisory controller monitors safety and target convergence, providing non-conservative intervention when the nominal controller violates necessary constraints. Experimental results include simulations and real robot deployment with various 2D and 3D datasets, including handwriting datasets, validating the effectiveness of our approach in providing formal guarantees with learned motion even in complex, dynamic environments.
Figures & tables
Fig. 1: The proposed pipeline follows the principle synthesize, supervise, and certify . Starting with the learned DS and a symbolic certified controller, our methodology synthesizes nominal controllers to follow the learned paths, supervises and checks for collision and reachability to the goal, and modifies the controller slightly to obtain certified inputs before executing them on the robot.
Fig. 2: Simulations showing the performance of our supervisory control method vs CLF-CBF [ 13 ] for four representative datasets: sine, G, snake, and khamesh, with different obstacle configurations.
Fig. 3: Online realization of our approach vs CLF-CBF on dynamic obstacles with sine motion; red arrows indicate the motion of the obstacles.
method
task success
collisions
vel. limit violations
acc. limit violations
path return rate
ours (Certified Supervisor)
95.67
0.0
0.0
0.0
93.33
CLF-CBF
65.67
18.0
0.0
43.33
53.33
TABLE I: Quantitative comparison on the task performance rates between our method and CLF-CBF. All criteria are evaluated over 300 aggregated DS-learning and tracking tasks, and are measured in % .
Method
MSE(mm)
DTW(mm)
acc. variation (m/s 2 )
navigation time (s)
Ours (Certified Supervisor)
7.46
14.613
0.249
23.27
CLF-CBF
18.98
17.551
0.02
24.5
TABLE II: Trajectory-fidelity and motion-quality comparison between the our method and the CLF-CBF baseline. All values are averaged over successful trials, aggregated across 10 LASA datsets, 3 learned ds models per motion ( lpv -DS, PolyDS, and NN-DS), and 10 motion trajectories per model.
Learning Method
Trials
ours
CBF-CLF
LPV-DS
100
99.00%
54.00%
PolyDS
100
100.00%
76.00%
NNDS
100
88.00%
67.00%
TABLE III: The learning method-family wise breakdown of the task success rates (ours vs CLF-CBF [ 13 ] ).
Fig. 4: Franka FR3 robot executing a learned C-shaped motion under manually applied perturbations, without an obstacle (left) and with a moving obstacle (right)
Fig. 5: End-effector trajectories when subject to perturbations at runtime using offline (left) and online (right) symbolic synthesis.
Dynamical Systems (DS) are reactive motion policies representing vector fields trained with theoretical guarantees of stability and convergence. To ensure safety during deployment in unknown environments they must be locally reshaped, either through modulation or geometric control barrier function strategies. However, depending on the geometry of the obstacles and the complexity of the DS, these local strategies can lead the system to unavoidable collisions or spurious attractors. In this work, we certify safety with a value function drawn from the notion of backward reachability tube, which measures the worst-case safety along a rollout trajectory of the nominal DS. Usually, such a value function is intractable for a controlled system due to curse of dimensionality. We show that in the DS-based learning-from-demonstration setting, the absence of a control input collapses the reachability problem to a deterministic rollout, and the presence of certain stability conditions truncates the infinite horizon to a finite one, resulting in a well-defined value function. We further show that the value function we devised is the maximal forward-invariant subset of the obstaclefree region for the nominal DS flow. The application of this certificate function is validated across five DS constructions - analytical, Neural ODE, diffeomorphic latent space, LPV-DS, SE(3)and validate it on a Franka manipulator. Modulation and geometric CBFs also suffer from saddle point in cases of headon approach towards an unsafe zone. We show that CBF-on-V avoids this pitfall entirely.
Aditya Vats, Tianyi Xia, Nadia Figueroa
The authors are with the University of Pennsylvania, Philadelphia, PA, USA.
We present STT-LfD, a unified Learning from Demonstration (LfD) framework that integrates motion learning with control for unknown Euler-Lagrange systems. Unlike traditional decoupled approaches that track a fixed reference, the proposed method treats demonstrations as a data-driven safety specification. Using heteroscedastic Gaussian Processes, STT-LfD learns Spatiotemporal Tubes (STTs) as an intent envelope that capture time-varying precision requirements of a task. A closed-form feedback controller then enforces these learned constraints while respecting actuator limits, without requiring explicit system identification. The approach preserves the temporal structure of demonstrations, remains computationally efficient, and avoids explicit system identification. Hardware experiments on a mobile robot and a 7-DOF manipulator show that it outperforms baselines in robustness to disturbances and computational speed.
Safe model-based reinforcement learning (RL) often bridges control-theoretic analysis and RL for robots to safely explore (partially) unknown system dynamics while deriving control actions for task efficiency. The control performance and safety assurance typically rely on prior knowledge of partially modeled nominal system dynamics and the data-driven models that compensate for residual model uncertainties. However, existing methods often overlook the structure of residual model uncertainties (e.g., components affine in control), which could lead to overly conservative robot behaviors or invalid safety guarantees under the safe learning-based controllers. This paper proposes a safe reinforcement learning framework that learns control-affine dynamics with a certifiable data-driven safe policy using control barrier functions (CBF). Specifically, we first use Control-Affine Random Fourier Features (ARFF) to model robot dynamics in a control-affine form, which offers computational efficiency that scales with dataset size and reduces potential model bias for model-based reinforcement learning. Then, a model-free, efficient uncertainty quantification method using adaptive conformal prediction (ACP) is applied to quantify the uncertainty in the safety constraint arising from the learned control-affine dynamics. This allows for data-driven safety assurance amenable to principled and efficient controller synthesis with CBF. Simulation results on the cartpole and the 3D quadrotor platforms demonstrate the effectiveness of the proposed framework.
Hao Zhou, Yanze Zhang, Cameron Reid +1
Department of Computer Science, University of Illinois Chicago, Chicago, IL 60607, USA · Department of Computer Science and Engineering, Texas A&M University, College Station, TX 77843, USA