4 research outputs found
A Benchmark Comparison of Imitation Learning-based Control Policies for Autonomous Racing
Autonomous racing with scaled race cars has gained increasing attention as an
effective approach for developing perception, planning and control algorithms
for safe autonomous driving at the limits of the vehicle's handling. To train
agile control policies for autonomous racing, learning-based approaches largely
utilize reinforcement learning, albeit with mixed results. In this study, we
benchmark a variety of imitation learning policies for racing vehicles that are
applied directly or for bootstrapping reinforcement learning both in simulation
and on scaled real-world environments. We show that interactive imitation
learning techniques outperform traditional imitation learning methods and can
greatly improve the performance of reinforcement learning policies by
bootstrapping thanks to its better sample efficiency. Our benchmarks provide a
foundation for future research on autonomous racing using Imitation Learning
and Reinforcement Learning
A Fast Singular Boundary Method for the Acoustic Design Sensitivity Analysis of Arbitrary Two- and Three-Dimensional Structures
This paper proposes a fast meshless scheme for acoustic sensitivity analysis by using the Burton–Miller-type singular boundary method (BM-SBM) and recursive skeletonization factorization (RSF). The Burton–Miller formulation was adopted to circumvent the fictitious frequency that occurs in external acoustic analysis, and then the direct differentiation method was used to obtain the sensitivity of sound pressure to design variables. More importantly, RSF was employed to solve the resultant linear system obtained by the BM-SBM. RSF is a fast direct factorization technique based on multilevel matrix compression, which allows fast factorization and application of the inverse in solving dense matrices. Firstly, the BM-SBM is a boundary-type collocation method that is a straightforward and accurate scheme owing to the use of the fundamental solution. Secondly, the introduction of the fast solver can effectively reduce the requirement of computer memory and increase the calculation scale compared to the conventional BM-SBM. Three numerical examples including two- and three-dimensional geometries indicate the precision and efficiency of the proposed fast numerical technique for acoustic design sensitivity analysis associated with large-scale and complicated structures