Research

Interpretable Learning-Based Control

Contents
  1. Overview
  2. Results
  3. Publications

Model predictive control laws learned as oblique decision trees, over 1,000× faster than online MPC.

Overview

Model predictive control (MPC) performs well but must solve an optimization problem online at every step. The control law of linear MPC is piecewise affine, so it can be represented exactly by an oblique decision tree with linear predictions at the leaf nodes. Building on this, I learn MPC laws as interpretable decision trees offline and deploy the tree online as the controller.

Equivalence between a linear MPC control law and an oblique decision tree, and the offline training / online control framework
(a) A linear MPC control law equals an oblique decision tree with linear predictions. (b) The tree is trained offline and deployed online as the controller.

Results

The resulting controllers perform competitively with MPC at the speed of a low-level PID controller: over 1,000× faster than MPC and 10× faster than neural network equivalents. I have extended this framework to quadcopter control and to interpretable reinforcement learning for multi-loop adaptive PID control.

Publications

IEEE CDC 2025

Exact Learning of Linear Model Predictive Control Laws Using Oblique Decision Trees with Linear Predictions

Ren, J., Mao, Q., Zhao, T., and Cao, Y.

64th IEEE Conference on Decision and Control, pp. 7018–7023 (2025).

DOI
IFAC WC 2026

Fast, High-Performance, and Interpretable Quadcopter Control Using Decision Trees

Ren, J., Juang, M.-H., Zhao, T., and Cao, Y.

23rd IFAC World Congress (2026).

IFAC WC 2026

Interpretable Reinforcement Learning for Multi-Loop Adaptive PID Control

Zhao, T., Ren, J., Zou, C., Yang, Y., Cao, Y., and Gopaluni, R.B.

23rd IFAC World Congress (2026).

IEEE T-ASE 2024

Deep Learning-Based Approximation of Model Predictive Control Laws Using Mixture Networks

Okamoto, M., Ren, J., Mao, Q., Liu, J., and Cao, Y.

IEEE Transactions on Automation Science and Engineering, 22: 2909–2922 (2024).

DOI
Energy 2025

Hierarchical Model Predictive Control for Energy Consumption Regulation of Industrial-Scale Circulation Counter-Flow Paddy Drying Process

Li, C.*, Ren, J.*, Seth, A., Zhang, Y., Huang, J., Li, C., and Cao, Y.

Energy, 321: 135431 (2025).

* Co-first authors

DOI