Video streaming based teleoperation often faces a trade-off between bandwidth consumption and the need for high-fidelity telepresence. Higher image resolution or a wider field of view (FOV) substantially increases bandwidth requirements. In this paper, we propose a novel telepresence model for teleoperated vehicles operating in bandwidth-constrained environments. Our approach employs a LiDAR-fused 3D Gaussian Splatting (3DGS) as a compact scene representation to efficiently generate remote views. Initially, a static point cloud map is constructed using LiDAR-based semantic mapping, which serves as the initial Gaussians for optimizing the 3DGS model. During teleoperation, the prebuilt 3DGS is then rendered on the teleoperation platform, while only safety-critical information, such as vehicle pose and dynamic objects, is transmitted from the vehicle to the teleoperator in real-time. The proposed telepresence model significantly reduces data transmission requirements while maintaining photorealistic telepresence, enabling reliable and effective teleoperation even under stringent bandwidth constraints. This capability ensures safe and efficient vehicle teleoperation under challenging environments without relying on traditional high-bandwidth communication, thereby broadening the applicability of teleoperation technology to more demanding and diverse operational scenarios. Real-world experimental results show that the developed system can provide immersive teleoperation experiences at Kbps-level bandwidth consumption.

This paper presents an analysis on flexible formations of nonholonomic mobile robots from the perspectives of motion planning and control. The formations are flexible in the sense that their formation configurations are defined based on curvilinear longitudinal and lateral relative separations instead of the commonly used rectilinear relative separations. And the mobile robots' motions considered here are kinodynamically constrained. In this work, we relate the formation maneuverability with the mobile robots' limited motion capabilities and the formation's configuration which in turn provides a measure on the formation's motion capabilities. In addition, useful findings pertaining to fundamental formations are also derived, which are advantageous for efficient and effective formation motion planning and control. These results lay a foundation to address the problems of planning kinodynamically feasible formation leader's trajectories to connect flexible formations between different locations such that every robot of the formation can follow its assigned formation point without violating it's kinodynamical motion constraints.

This paper addresses the distributed formation trajectory planning for a group of nonholonomic vehicles. This is realized with a decentralized Model Predictive Control under dynamic virtual structure architecture. A specific limitation of virtual structure based formation method is the necessity of access to the desired reference. To remove this requirement, a distributed estimator is developed so that each vehicle can construct the desired reference based on the local information exchange. In formation trajectory planning, several issues are taken into consideration which includes: (i) distributed formation achievement by a team of nonholonomic vehicles from initial situation. (ii) inter-group collision avoidance. (iii) dynamic formation to obtain flexible manoeuvring during movement in unknown and cluttered environment. (iv) obstacle avoidance. Finally, simulation results are presented to illustrate the performance of the proposed methodology in producing optimal formation trajectory planning for multiple nonholonomic vehicles.

Hybrid systems operate in various states, which are represented by a set of modes. In each mode, the system is governed by continuous dynamics, and different modes correspond to different continuous models. For hybrid systems, model-based fault detection and isolation is a challenging task due to the fact that the system's prevailing dynamical model and its current mode (discrete state) are mutually dependent and intertwined. In this paper, a new energy-based approach is introduced for mode tracking of hybrid systems, and its associated systematic analysis is based on a hybrid bond graph. Each system's mode is characterized by a concise energy relation that allows mode identification in the new mode tracking method.

This research result consists of two parts: one is general theory on causality assignment for hybrid bond graph (HBG) and another is application of this concept to the quantitative fault diagnosis. From Low et al., 2008, a foundation for quantitative bond graph-based fault detection and isolation (FDI) design using HBG is laid. Useful causality properties pertaining to the HBG from FDI perspectives, and the concept of diagnostic hybrid bond graph (DHBG) which is advantageous for efficient and effective FDI applications are proposed. This paper is a continuation of our previous paper (Low et al., 2008). Here, the DHBG is exploited to analyze the hybrid system's fault detectability and fault isolability. Additionally, a quantitative FDI framework for effective fault diagnosis for hybrid systems is proposed. Simulation and experimental results are presented to validate some key concepts of the quantitative hybrid bond graph-based FDI framework.

Bond graph (BG) is an effective tool for modeling complex systems and it has been proven useful for fault detection and isolation (FDI) for continuous systems. BG provides the causal relations between system's variables which allow FDI algorithms to be developed systematically from the graph. In the same spirit, Hybrid bond graph (HBG) is a BG-based modeling approach which provides an avenue to model complex hybrid systems. However, due to mode-varying causality properties of HBG, HBG has not been efficiently-exploited for fault diagnosis. In this work, a comprehensive study on the HBG from FDI viewpoints is presented. Some properties pertaining to the HBG are gained in the study. Based on these findings, a causality assignment procedure and a model approximation technique are developed to achieve a HBG with a desirable causality assignment that leads a unified description of system's behavior. These results lay a foundation for quantitative FDI design for complex hybrid systems.

In this work we present a new health monitoring method for hybrid systems. The method utilizes the concept of unified constraint relations, named the global analytical redundancy relations (GARRs). Using GARRs for health monitoring of hybrid system requires the system's current mode and this information is provided by a mode tracker. To make the mode tracking more efficient, a unique mode-change isolation process is utilized, this process is based on the mode change signature matrix (MCSM).

This paper aims to give a general and unifying presentation on modeling of wheel mobile robots (WMRs) in the presence of wheel skidding and slipping from the perspective of control design. We present kinematic models that explicitly relate perturbations to the vehicle skidding and slipping. Four configurations of mobile robots are considered, and perturbations due to skidding and slipping are categorically classified as input-additive, input multiplicative, and/or matched/unmatched perturbations. Furthermore, we relate the WMR's maneuverability with the vehicle controllability that provides a measure on the WMR ability to track a trajectory in the presence of wheel skidding and slipping. These classifications and formulations lay a base for the deployments of various control design techniques to overcome the addressed perturbations.

This paper presents a scheme for high-update rate wheel mobile robot (WMR) posture, velocities, and perturbation estimation using real-time kinematic global positioning system (RTK-GPS) and inertial sensors for WMR control in the presence of wheel skidding and slipping. An outdoor estimation system based on Kalman filtering combines the inertial measurements with centimeter accuracy RTK-GPS measurements to provide essential posture, velocities, and perturbation information. The particular contribution of this paper is in designing an estimation system to be able to deal with WMR control problems in the presence of wheel skidding and slipping. The experimental results suggest that with careful modelling of WMR, the estimation scheme is able to provide reliable and high update rate information for WMR control applications in the presence of wheel skidding and slipping.

This paper presents an analysis on wheeled mobile robots in the presence of wheel skidding and slipping from the perspective of control design. The analysis is based on the kinematic models that are recently developed from control perspective (Wang and Low 2006). Four generic mobile robots are considered in this analysis. We relate the robot's maneuverability with its controllability which provides insights on the robot's ability to track a trajectory in the presence of wheel skidding and slipping. These findings lay a base for the deployments of various control design techniques to overcome mobile robot control problems in the presence of wheel skidding and slipping.

This present paper aims to give a general and unifying presentation on modeling of WMRs in the presence of wheel skidding and slipping from the perspective of control design. We present kinematic models that explicitly relate the perturbations to the vehicle skidding and slipping. Four configurations of mobile robots are considered and the perturbations due to skidding and slipping are categorically classified as input additive, input multiplicative, and/or matched/unmatched perturbations. These classifications and formulations lay a base for the deployments of various control design techniques to overcome the addressed perturbations

This paper presents a fault-tolerant tracking controller for a platoon of two mobile robots. A vehicle model and a unified controller are proposed for both look-ahead and look-behind tracking of a four-wheel-steering vehicle. The controller can handle situations where faults occur at the two steering systems of the vehicle by making use of any operational systems to steer the vehicle. Tracking stability is ensured by the proper selection of design parameters. Experimental results show the control scheme work properly even in the situations when faults are on and off often at different parts of the vehicle

Positioning of a mobile robot is critical to its movement in an outdoor environment to accomplish tasks with success and accuracy. For outdoor automation with a fleet of mobile robots in a local area, a common positioning system for all vehicles is essential for maneuvering and coordination. The positioning system should be referenced to a global coordinate frame and requires few artificial landmarks only for the areas that are out of the GPS positioning system. In addition, positioning system is desirable to have a high update rate for real-time control purposes. In this paper, we propose an integrated positioning system (IPS), which is able to provide an accurate and high update rate position estimate. The integrated system utilizes GPS as the global coordinate positioning system, Nav200 as the local positioning system for areas that are not covered by GPS signals and encoders/compass as the supplementary relative positioning system. The structure of the IPS and techniques are described. Experimental results are presented to show the working and output of the IPS.