Physics-Informed Neural Networks-based Model Predictive Control for Multi-link Manipulators

Prospective contribution to the MATHMOD 2022 Vienna conference.

About The Project

We discuss nonlinear model predictive control (NMPC) for multi-body dynamics via physics-informed machine learning methods. Physics-informed neural networks (PINNs) are a promising tool to approximate (partial) differential equations. PINNs are not suited for control tasks in their original form since they are not designed to handle variable control actions or variable initial values. We thus present the idea of enhancing PINNs by adding control actions and initial conditions as additional network inputs. The high-dimensional input space is subsequently reduced via a sampling strategy and a zero-hold assumption. This strategy enables the controller design based on a PINN as an approximation of the underlying system dynamics. The additional benefit is that the sensitivities are easily computed via automatic differentiation, thus leading to efficient gradient-based algorithms. Finally, we present our results using our PINN-based MPC to solve a tracking problem for a complex mechanical system, a multi-link manipulator.

Citing

If you use this project for academic work, please consider citing our publication:

Jonas Nicodemus, Jonas Kneifl, Jörg Fehr, Benjamin Unger,
Physics-informed Neural Networks-based Model Predictive Control for Multi-link Manipulators,
IFAC-PapersOnLine, Volume 55, Issue 20, 2022.

Built With

• TensorFlow
• Python

Getting Started

To get a local copy up and running follow these simple steps.

Prerequisites

A python environment is required, we recommend using a virtual environment.

Installation

1. Clone the repo

   git clone [email protected]:Jonas-Nicodemus/PINNs-based-MPC.git
   

2. Go into the directory

   cd PINNs-based-MPC
   

3. Install dependencies

   pip install -r requirements.txt
   

Usage

There are two executable scripts located in src.

• train_pinn.py can be executed to learn weights and overwrite the already existing ones, which can be found under resources/weights.
• main.py, then evaluates the PINN first in self-loop prediction mode and subsequently in closed-loop mode connected to the real system (emulated by RK45) for the given reference trajectory.

License

Distributed under the MIT License. See LICENSE for more information.

Contact

Jonas Nicodemus - [email protected]

Benjamin Unger - [email protected]

Jonas Kneifl - [email protected]

Jörg Fehr - [email protected]

Project Link: https://github.com/Jonas-Nicodemus/PINNs-based-MPC