Real-time Gaussian Process based Approximate Model Predictive Trajectory Tracking Control for Autonomous Vehicles

TL;DR

This paper introduces a Gaussian process-based approximation method for real-time trajectory tracking control in autonomous vehicles, significantly reducing computation time while maintaining performance.

Contribution

The authors propose a curvilinear coordinate transformation and residual learning approach to improve data efficiency in Gaussian process model predictive control for autonomous vehicles.

Findings

Control inputs computed five times faster than real-time iteration MPC.

Achieved similar tracking performance with reduced computational cost.

Validated approach on a small-scale vehicle with embedded Raspberry Pi.

Abstract

Applying model predictive control on embedded systems remains challenging due to the high computational cost of solving optimal control problems. To address this limitation, computationally efficient Gaussian process approximations of the implicit model predictive control law can be employed. However, for trajectory-tracking applications, the large amount of training data required for successful generalization across distinct reference trajectories poses a significant challenge. To improve data efficiency, we propose to transform the model into curvilinear coordinates around the reference trajectory. Secondly, we use a nominal feedforward component, allowing the Gaussian process to learn only the residual control input, making the approximation of a trajectory-tracking controller feasible. To underline the applicability of the approach, we deploy the controller on a Raspberry Pi in a small-scale vehicle and validate it experimentally. Compared to a model predictive control implementation using real-time iterations, the Gaussian process based approximation computes control inputs about five times faster while achieving similar closed-loop tracking performance.