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Fälldin, Arvid
Publications (2 of 2) Show all publications
Aoshima, K., Fälldin, A., Wadbro, E. & Servin, M.Data-driven models for predicting the outcome of autonomous wheel loader operations.
Open this publication in new window or tab >>Data-driven models for predicting the outcome of autonomous wheel loader operations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

This paper presents a method using data-driven models for selecting actions and predicting the total performance of autonomous wheel loader operations over many loading cycles in a changing environment. The performance includes loaded mass, loading time, work. The data-driven models input the control parameters of a loading action and the heightmap of the initial pile state to output the inference of either the performance or the resulting pile state. By iteratively utilizing the resulting pile state as the initial pile state for consecutive predictions, the prediction method enables long-horizon forecasting. Deep neural networks were trained on data from over 10,000 random loading actions in gravel piles of different shapes using 3D multibody dynamics simulation. The models predict the performance and the resulting pile state with, on average, 95% accuracy in 1.2 ms, and 97% in 4.5 ms, respectively. The performance prediction was found to be even faster in exchange for accuracy by reducing the model size with the lower dimensional representation of the pile state using its slope and curvature. The feasibility of long-horizon predictions was confirmed with 40 sequential loading actions at a large pile. With the aid of a physics-based model, the pile state predictions are kept sufficiently accurate for longer-horizon use.

National Category
Other Physics Topics Computer Vision and Robotics (Autonomous Systems) Transport Systems and Logistics Robotics
Research subject
Physics
Identifiers
urn:nbn:se:umu:diva-220410 (URN)10.48550/arXiv.2309.12016 (DOI)
Available from: 2024-02-02 Created: 2024-02-02 Last updated: 2024-02-05
Wiberg, V., Wallin, E., Fälldin, A., Semberg, T., Rossander, M., Wadbro, E. & Servin, M.Sim-to-real transfer of active suspension control using deep reinforcement learning.
Open this publication in new window or tab >>Sim-to-real transfer of active suspension control using deep reinforcement learning
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

We explore sim-to-real transfer of deep reinforcement learning controllers for a heavy vehicle with active suspensions designed for traversing rough terrain. While related research primarily focuses on lightweight robots with electric motors and fast actuation, this study uses a forestry vehicle with a complex hydraulic driveline and slow actuation. We simulate the vehicle using multibody dynamics and apply system identification to find an appropriate set of simulation parameters. We then train policies in simulation using various techniques to mitigate the sim-to-real gap, including domain randomization, action delays, and a reward penalty to encourage smooth control. In reality, the policies trained with action delays and a penalty for erratic actions perform at nearly the same level as in simulation. In experiments on level ground, the motion trajectories closely overlap when turning to either side, as well as in a route tracking scenario. When faced with a ramp that requires active use of the suspensions, the simulated and real motions are in close alignment. This shows that the actuator model together with system identification yields a sufficiently accurate model of the actuators. We observe that policies trained without the additional action penalty exhibit fast switching or bang-bang control. These present smooth motions and high performance in simulation but transfer poorly to reality. We find that policies make marginal use of the local height map for perception, showing no indications of look-ahead planning. However, the strong transfer capabilities entail that further development concerning perception and performance can be largely confined to simulation. 

Keywords
autonomous vehicles, rough terrain navigation, machine learning, sim-to-real, reinforcement learning, heavy vehicles
National Category
Computer Vision and Robotics (Autonomous Systems) Other Physics Topics
Research subject
Physics; computer and systems sciences
Identifiers
urn:nbn:se:umu:diva-207977 (URN)10.48550/arXiv.2306.11171 (DOI)
Funder
Mistra - The Swedish Foundation for Strategic Environmental Research, DIA 2017/14 #6
Available from: 2023-05-05 Created: 2023-05-05 Last updated: 2023-07-04Bibliographically approved
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