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This paper presents an adaptive control allocation technique for over-actuated systems. The online actuator selection algorithm is used to select the best group of actuators. Also, a multi-objective cost function is utilized for the allocation unit. The virtual and actual control signals in the control allocation methodologies are linked by the effectiveness matrix . In many practical systems, the elements of the effectiveness matrix may vary due to changing operating conditions, nonlinearities, ageing, disturbances and faults. Hence, an online algorithm for estimation of the entries of the effectiveness matrix is presented in this paper. Estimation of the effectiveness matrix will be used for the proposed adaptive actuator selection strategy, employing the Actuator Effectiveness Index (AEI). The AEI is calculated for all the actuators, and the best group of actuators will be subsequently selected. Finally, simulation results are used to show the effectiveness of the proposed methodology.

Integrated chassis control systems represent a significant advancement in the dynamics of ground vehicles, aimed at enhancing overall performance, comfort, handling, and stability. As vehicles transition from internal combustion to electric platforms, integrated chassis control systems have evolved to meet the demands of electrification and automation. This paper analyses the overall control structure of automated vehicles with integrated chassis control systems. Integration of longitudinal, lateral, and vertical systems presents complexities due to the overlapping control regions of various subsystems. The presented methodology includes a comprehensive examination of state-of-the-art technologies, focusing on algorithms to manage control actions and prevent interference between subsystems. The results underscore the importance of control allocation to exploit the additional degrees of freedom offered by over-actuated systems. This paper systematically overviews the various control methods applied in integrated chassis control and path tracking. This includes a detailed examination of perception and decision-making, parameter estimation techniques, reference generation strategies, and the hierarchy of controllers, encompassing high-level, middle-level, and low-level control components. By offering this systematic overview, this paper aims to facilitate a deeper understanding of the diverse control methods employed in automated driving with integrated chassis control, providing insights into their applications, strengths, and limitations.

This paper proposes a design technique for vehicle lateral stability control. In this structure, reference variables are first determined based on the driver’s input. Using a fixed-time control technique, an upper controller, also known as virtual control, is designed to ensure vehicle stability for the desired yaw moment. Subsequently, optimal braking forces, also known as lower controls, are designed by virtual control and are utilized to generate the control inputs for the actuators. The optimal braking forces, which are constrained, are designed using a fixed-time dynamic control allocation method. This ensures their convergence to optimal values in a fixed time. Unlike static optimization methods, the proposed control allocation method introduces a dynamic update law. This approach not only reduces computational complexity but also guarantees the fixed-time convergence of braking forces to the optimal solution. The overall closed-loop stability in constant time is also achievable via the Lyapunov stability method. Simulations were conducted on a 10-DOF nonlinear dynamic vehicle model for standard test maneuvers of the electronic stability control system. The results indicate that the proposed method outperforms numerical optimization-based methods such as weighted least squares, weighted pseudoinverse, and asymptotic dynamic control allocation in terms of efficiency.

On-demand urban air transportation gains popularity in recent years with the introduction of the electric VTOL (eVTOL) aircraft concept. There is an emerging interest in short/medium range eVTOL air taxi considering the critical advantages of electric propulsion (i.e. low noise and carbon emission). Using several electric propulsion systems (distributed electric propulsion (DEP)) has further advantages such as improved redundancy. However, flight controller design becomes more challenging due to highly over-actuated and coupled dynamics. This study defines and resolves flight control problems of a novel DEP eVTOL air taxi. The aircraft has a fixed-wing surface to have aerodynamically efficient cruise flight, and uses only tilting electric propulsion units to achieve full envelope flight control via pure thrust vector control. The aircraft does not have conventional control surfaces such as aileron, rudder or elevator. Using pure thrust vector control has some design benefits, but the control problem becomes more challenging due to the over-actuated and highly coupled dynamics (especially in transition flight). A preliminary flight dynamics model is obtained considering the dominant effects at hover and high-speed forward flight. Hover and forward flight models are blended to simulate the transition dynamics. Two central challenges regarding the flight control are significant nonlinearities in aircraft dynamics during the transition and proper allocation of the thrust vector control specifically in limited control authority (actuator saturation). The former challenge is resolved via designing a sensor-based incremental nonlinear dynamic inversion (INDI) controller to have a single/unified controller covering the wide flight envelope. For the latter one, an optimisation-based control allocation (CA) approach is integrated into the INDI controller. CA requires special attention due to the pure thrust vector control’s highly coupled dynamics. The controller shows satisfactory performance and disturbance rejection characteristics. Moreover, the CA plays a vital role in guaranteeing stable flight in case of severe actuator saturation.

This paper reviews theoretical and empirical work on financial contracting that is relevant to accounting researchers. Its primary objective is to discuss how the use of accounting information in contracts enhances contracting efficiency and to suggest avenues for future research. We argue that incomplete contract theory broadens our understanding of both the role accounting information plays in contracting and the mechanisms through which efficiency gains are achieved. By discussing its rich theoretical implications, we expect incomplete contract theory to prove useful in motivating future research and in offering directions to advance our knowledge of how accounting information affects contract efficiency.

This paper presents a new flight control framework for tiltrotor multirotor uncrewed aerial vehicles (MRUAVs). Tiltrotor designs offer full actuation but introduce complexity in control allocation due to actuator redundancy. We propose a new approach where the allocator is tightly coupled with the controller, ensuring that the control signals generated by the controller are feasible within the vehicle actuation space. We leverage Nonlinear Model Predictive Control (NMPC) to implement the above framework, providing feasible control signals and optimizing performance. This unified control structure simultaneously manages both position and attitude, which eliminates the need for cascaded position and attitude control loops. Extensive numerical experiments demonstrate that our approach significantly outperforms conventional techniques that are based on Linear Quadratic Regulator (LQR) and Sliding Mode Control (SMC), especially in high-acceleration trajectories and disturbance rejection scenarios, making the proposed approach a viable option for enhanced control precision and robustness, particularly in challenging missions.

Fault-tolerant control systems are vital in many industrial systems. Actuator redundancy is employed in advanced control strategies to increase system maneuverability, flexibility, safety, and fault tolerability. In this paper, a fault-tolerant control scheme is proposed to make an over-actuated octorotor robust, against actuators fault and saturation. A sliding mode observer is employed to determine the actuators condition. Then, a fault-tolerant control based on the control allocation methodology is proposed to distribute the control signals between the actuators by considering their condition. In a nonlinear system, an actuator fault can lead to the saturation of other actuators and steady-state errors that can cause closed-loop instability. Hence, the proposed control scheme corrects the actuator signals in a way that their limitations are considered. Finally, experimental studies are carried out and a comparison study is provided.

This paper investigates a predefined‐time compound tracking control scheme for hybrid‐actuator missiles to address the concurrent challenges posed by external disturbances, actuator saturation, and partial actuator failures. An improved predefined‐time prescribed performance function (PTPPF) with single‐sided monotonic boundaries is proposed to confine tracking errors within preassigned ranges, which effectively suppresses potential overshoot and prevents excessive initial control commands. By combining the improved PTPPF with a novel nonsingular sliding mode manifold based on hyperbolic functions, a predefined‐time prescribed performance control (PTPPC) is developed to guarantee accelerated convergence and superior transient tracking performance. Besides, an auxiliary system is introduced to compensate for mismatches between virtual and actual control inputs caused by actuator saturation and allocation inaccuracies, which can effectively enhance overall control accuracy. Furthermore, a predefined‐time adaptive control allocation (PTACA) strategy is designed to dynamically distribute virtual control commands among aerodynamic surfaces and lateral thrusters. The proposed PTACA explicitly accounts for actuator saturation and partial actuator failures, which improves control efficiency and minimises energy utilisation. The theoretical stability of the entire control framework is established via Lyapunov analysis. Finally, comparative numerical simulations are conducted to validate the effectiveness and superiority of the proposed scheme. This paper investigates the predefined‐time compound tracking control scheme integrating prescribed performance control and adaptive allocation for hybrid‐actuator missiles, addressing concurrent challenges of external disturbances, actuator saturation, and partial actuator failures. The proposed predefined‐time prescribed performance function with single‐sided monotonic boundaries can enforce superior transient and steady‐state tracking performance while preventing excessive initial control inputs and suppressing overshoot phenomena. The designed control allocation strategy can dynamically redistribute virtual control commands among actuators, explicitly addressing saturation effects and partial actuator failures while optimising control efficiency and minimising energy loss.

A novel combination of finite time control and control allocation with uncertain configuration matrix due to actuator misalignment is investigated for attitude stabilization of a rigid spacecraft. Finite time controller using nonsingular terminal sliding mode technique is firstly designed as virtual control of control allocator to produce the three axis torques, and can guarantee finite time reachability of given attitude motion of spacecraft in the presence of external disturbances. The convergences of this feedback controller for the resulting closed loop systems are also proven theoretically. Then, under the condition of uncertainty included in the configuration matrix due to actuator misalignment, a robust least squares-based control allocation is employed to deal with the problem of distributing the three axis torques over the available actuators under redundancy, in which the focus of this control allocation is to find the optimal control vector of actuator by minimizing the worst-case residual, under the condition of the uncertainty included in actuator configuration matrix and control constraints like saturation. Simulation results using the orbiting spacecraft model show good performance under external disturbances and even uncertain configuration matrix, which validates the effectiveness and feasibility of the proposed scheme.

Distributed electronic propulsion (DEP) aircraft with vertical take‐off and landing (VTOL) ability mostly equipped with multiple redundant tiltable propulsors, which are used to provide not only thrusts, but also control torque in all flight mode. The features make the control allocation problem of these aircraft both complex and important. Therefore, this paper proposes: (і) a prototype platform for DEP VTOL aircraft that allows researchers to design and analyse control allocation strategies, and (іі) a uniform hierarchical control allocation method that can be adapted to both MC and FW modes. The platform contains ten fully actuated thrusters, which are distributed in the scaled geometry of a typical DEP‐VTOL aircraft. The proposed control allocation strategy uses hierarchical structure to avoid high‐dimensional matrix operations for the redundant actuators. The additional constraints on the thrust and tilt angles of the actuators are addressed by adopting cascade generalized inversion (CGI) to force decompensation (FD)‐based methods by a coordinate transformation. A novel smooth strategy through Schur Complement is also presented to achieve steady and smooth transition from MC to FW mode. Finally, the proposed method is implemented in the authors’ novel platform in both simulations and flight experiments to demonstrate its effectiveness and smoothness. This paper proposes: (1) a test platform for DEP VTOL aircraft that allows researchers to design and analyze control allocation strategies, and (2) a uniform hierarchical control allocation method that can be adapted to both MC and FW modes.