Control of a nonlinear liquid level system using a new artificial neural network based reinforcement learning approach

• Published in: Applied soft computing 2014-10, Vol.23, p.444-451
• Main Authors: Noel, Mathew Mithra, Pandian, B. Jaganatha
• Format: Article
• Language: English
• Subjects: Neural networks; Nonlinear control; Process control; Reinforcement learning
• ISSN: 1568-4946; 1872-9681
• DOI: 10.1016/j.asoc.2014.06.037

•A neural network based reinforcement learning control strategy has been proposed.•Neural network and reinforcement learning paradigms are synergistically combined.•The proposed strategies are tested on two benchmark nonlinear control problem.•Simulation results indicate good performance on nonlinear regulation problems. Most industrial processes exhibit inherent nonlinear characteristics. Hence, classical control strategies which use linearized models are not effective in achieving optimal control. In this paper an Artificial Neural Network (ANN) based reinforcement learning (RL) strategy is proposed for controlling a nonlinear interacting liquid level system. This ANN-RL control strategy takes advantage of the generalization, noise immunity and function approximation capabilities of the ANN and optimal decision making capabilities of the RL approach. Two different ANN-RL approaches for solving a generic nonlinear control problem are proposed and their performances are evaluated by applying them to two benchmark nonlinear liquid level control problems. Comparison of the ANN-RL approach is also made to a discretized state space based pure RL control strategy. Performance comparison on the benchmark nonlinear liquid level control problems indicate that the ANN-RL approach results in better control as evidenced by less oscillations, disturbance rejection and overshoot.