This paper presents a robust actuator fault detection and diagnosis (FDD) scheme for a quadrotor UAV (QUAV) in the presence of external disturbances. First, the dynamic model of a QUAV taking into account actuator faults and external disturbances is constructed. Then, treating the actuator faults and external disturbances as augmented system states, an adaptive augmented state Kalman filter (AASKF), is developed without the need of make the assumption that the exact stochastic information of actuator faults and external disturbances are available. Next, in order to reduce the computational load of AASKF, an adaptive three-stage Kalman filter (AThSKF) is proposed by decoupling the AASKF into three subfilters. The AThSKF-based FDD scheme can not only detect and isolate actuator faults but also estimate the magnitudes even if the QUAV suffers from the external disturbances. Finally, the performance of the FDD scheme is evaluated under different fault scenarios, and simulation results demonstrate the effectiveness of the proposed method.

A safe time-varying formation (TVF) control framework is proposed in this article for heterogeneous multiagent systems under the constraints of denial of service (DoS) attacks, noncooperative dynamic obstacles, and input saturation. The framework integrates both the cyber-layer and physical-layer components to address the challenges posed by these adverse conditions. In the cyber-layer, a distributed resilient observer is provided based on a control Lyapunov function (CLF)-quadratic program (QP). This observer estimates a reference exosystem, effectively decoupling heterogeneous dynamics from unsafe networks and optimizing the system resilience against DoS attacks. At the physical-layer, for the first time, a collision-free TVF controller is presented based on the CLF-exponential control barrier function-QP. The controller guarantees high-order heterogeneous agents’ operation safety under noncooperative obstacles and input saturation. The effectiveness and advantages of the proposed algorithms are verified through the comparative simulations and experiments conducted on a physical system comprising unmanned aerial vehicles and unmanned ground vehicles.

This paper investigates the fault detection and diagnosis (FDD) problem for multiagent systems subject to sensor faults and disturbances. A distributed proportional integral derivative formation control protocol is constructed to achieve practical formation. A distributed FDD scheme, comprised of a fault detection module, a fault isolation module, and a fault estimation module, is designed within the formation control. For fault detection, the relationship between residuals and sensor faults in the multiagent systems is established such that each agent can detect the faults of all agents. For fault isolation, the distributed observer in each agent can determine whether the fault is in itself or its neighbors. Utilizing the absolute output information of each agent and the relative output information among neighboring agents, a distributed fault estimator is derived to provide the fault magnitude information. Simulation results are presented to demonstrate the effectiveness of the proposed FDD scheme.

Simultaneous localization and mapping (SLAM) is one of the prerequisite technologies for intelligent mobile robots to accomplish various tasks in unknown environments. In recent years, many excellent SLAM systems have emerged, but most of them have a basic assumption that the environment is static, which results in their poor performance in dynamic environments. To solve this problem, this paper presents SCE-SLAM: a novel real-time semantic RGB-D SLAM system that is built on the RGB-D mode of ORB-SLAM3. SCE-SLAM tightly combines semantic and geometric information. Considering the real-time requirements, the semantic module provides semantic prior knowledge for the geometric module using the latest and fastest object detection network YOLOv7. Then, a new geometric constraint method is proposed to filter dynamic feature points. This method takes full advantage of depth images and semantic information to recover three-dimensional (3D) feature points and the initial camera pose. A 3D coordinate error is used as a threshold, and SCE-SLAM removes dynamic points using the K-means clustering algorithm. In this way, SCE-SLAM effectively reduces the impact of dynamic points. Furthermore, we validate SCE-SLAM with challenging dynamic sequences of the TUM dataset. The results demonstrate that SCE-SLAM significantly improves the localization accuracy and system robustness in all kinds of dynamic environments.