Predictor-Based Control for Delay Compensation in Bilateral Teleoperation of Wheeled Rovers on Soft Terrains

The challenges posed by terrain-induced slippage for wheeled rovers traversing soft terrains (e.g. lunar terrain) are critical to ensuring safe operation. Bilateral teleoperation systems present a promising solution to this issue, by conveying the slippage information as haptic feedback to the operator. However, communication delays present a significant challenge to achieving a high-fidelity closed-loop system, leading to reduced situational awareness and poor command-tracking performance. This paper proposes a first-order time-delayed (FOTD) predictor-based control scheme to design an effective bilateral teleoperation system. The closed-loop stability of the teleoperation system is analyzed in the presence of large delays. Our analysis revealed that while the conventional PD-like control scheme keeps the closed-loop teleoperation system stable, it performs poorly. In contrast, our proposed FOTD control scheme effectively stabilizes the closed-loop system without compromising performance. In our case study, we evaluated a bilateral teleoperated rover subjected to slippage and large delays encountered in lunar exploration. The FOTD control scheme successfully compensated for 75.9% of the delays in the simulations and 63.2% of the delays in the experiments. This effective compensation leads to higher fidelity closed-loop integration and better command-tracking performance. Furthermore, a comparative study demonstrates that our FOTD-controlled teleoperation approach exhibits less slippage and reduced task completion time, resulting in a higher task success rate compared to both PD-like-controlled and traditional teleoperation approaches.