Localization Uncertainty-driven Adaptive Framework for Controlling Ground Vehicle Robots

Modern localization techniques allow ground vehicle robots to determine their position with centimeter-level accuracy under nominal conditions, enabling them to utilize fixed maps to navigate their environments. However, when localization measurements become unavailable, the position accuracy will drop and uncertainty will increase. While research and development on localization estimation seeks to reduce the severity of these outages, the question of what actions a robot should take under high localization uncertainty is still unresolved, and can vary on a platform-by-platform and mission-by-mission basis. In this paper, we exploit localization uncertainty measures to adapt system control parameters in real time. Offline, we optimize non-linear activation functions whose control parameters and relevant weights are trained and learned using Evolutionary Algorithm (EA). Subsequently, in real time, we apply the optimized adaptation functions to the controller look-ahead distance and intermediate linear and angular velocity commands, which we identify as the most sensitive to localization error. Evolutionary runs are conducted in which a simulated target vehicle is tasked with following a randomly generated path while minimizing cross-track error, with time varying localization uncertainty added. These runs produce situation-dependent weights for parameters to the adaptation functions, which are transferred to the physical platform, a 1:5-scale autonomous vehicle. In simulation, our system was able to reduce cross-track error, which in certain cases exceeds 250 centimeters on non-adapted systems, to below 15 centimeters on average using EA-derived weights and parameters applied to our proposed adaptation system. Evaluation on the physical platform demonstrates that without the adaptation module in place, the platform is unable to successfully follow the path; with the adaptation module, the platform automatically adjusts its velocity and look-ahead distance to compensate for localization uncertainty.