Automatic parameter tuning methods for planning algorithms, which integrate pipeline approaches with learning-based techniques, are regarded as promising due to their stability and capability to handle highly constrained environments. While existing parameter tuning methods have demonstrated considerable success, further performance improvements require a more structured approach. In this paper, we propose a hierarchical architecture for reinforcement learning-based parameter tuning. The architecture introduces a hierarchical structure with low-frequency parameter tuning, mid-frequency planning, and high-frequency control, enabling concurrent enhancement of both upper-layer parameter tuning and lower-layer control through iterative training. Experimental evaluations in both simulated and real-world environments show that our method surpasses existing parameter tuning approaches. Furthermore, our approach achieves first place in the Benchmark for Autonomous Robot Navigation (BARN) Challenge.

It is a challenging task for ground robots to autonomously navigate in harsh environments due to the presence of non-trivial obstacles and uneven terrain. This requires trajectory planning that balances safety and efficiency. The primary challenge is to generate a feasible trajectory that prevents robot from tip-over while ensuring effective navigation. In this paper, we propose a capsizing-aware trajectory planner (CAP) to achieve trajectory planning on the uneven terrain. The tip-over stability of the robot on rough terrain is analyzed. Based on the tip-over stability, we define the traversable orientation, which indicates the safe range of robot orientations. This orientation is then incorporated into a capsizing-safety constraint for trajectory optimization. We employ a graph-based solver to compute a robust and feasible trajectory while adhering to the capsizing-safety constraint. Extensive simulation and real-world experiments validate the effectiveness and robustness of the proposed method. The results demonstrate that CAP outperforms existing state-of-the-art approaches, providing enhanced navigation performance on uneven terrains.

This paper introduces an optimisation-based trajectory deformation and tracking algorithm for tethered differential-driven mobile robots. The motivation of this work is to generate self-entanglement-free (SEF) commands for a tethered differential-driven robot to track a path. Whilst existing path planners have been capable of generating SEF paths for tethered differential-driven robots lacking an omni-directional tether retracting mechanism, no trajectory planner can handle the unavoidable movement errors that cause robot pose deviate from the pre-defined path. The trajectory deformation and tracking is challenging because the admissible heading direction of the robot is highly constrained by the SEF constraint. As a result, even with an SEF path, the robot still encounters self-entanglement issues during execution.This paper fills this gap by formulating the trajectory deforming and tracking (TDT) problem of a tethered robot into a multi-objective optimisation framework. Explicit consideration of the constraint of the relative angle between the tether stretching direction and the robot’s heading direction to be admissible during its movement is provided in this framework. The proposed algorithm repeatedly deforms the pre-defined path for easier tracking, whilst generating a suitable velocity profile for robot execution. Compared to directly applying the commonly used untethered trajectory deformation and tracking algorithm into tethered cases, the proposed algorithm demonstrates improved performance in terms of minimising the risk of self-entanglement and maximising robot safety. These are validated in both simulated and real scenarios. An open-sourcesourcing implementation has also been provided for the benefit of the robotics community.

Global trajectory planning is crucial for long-range formation navigation tasks of multi-robot systems in efficiency improvement and energy saving, whose main challenges are the joint space constraints of the whole team and the long-range deployment. To overcome the above difficulties, we reformulate the original problem into an affine formation planning problem in parameter space. Further, we propose a front-end & back-end framework for global trajectory planning of Multi-Robot Systems (MRS) with affinely deformable formation. For the front-end, an RL-steering affine formation RRT* method is designed to search a global formation-level trajectory in affine parameter space, combining the efficient BVP-solving capability of RL and the global guidance and generalizing ability of RRT*. For the back-end, we propose a formationlevel affine parameter trajectory optimization method to refine the front-end trajectory, and further transform it into peragent trajectories for execution. Extensive benchmarks and ablation experiments in simulation show the effectiveness of our framework for the global trajectory generation of a multiUAV system with affinely deformable formation. The appendix can be seen here3.