This work presents the design of an event-driven position tracking control law for a nano unmanned helicopter with a body length less than 25 centimeters and a mass less than 70 grams. A robust geometric controller based on robust integral sign error (RISE) is devised to compensate for the unmanned helicopter’s modeling uncertainties as well as unknown external disturbances. An event-driven robust nonlinear control technique is formulated for the nano helicopter’s position loop control taking into account the very limited onboard computing resources of the nano unmanned helicopter. The stability of the helicopter’s closed-loop system is analyzed. And practical flying experiments are performed to verify the efficiency of the control method. The experimental results demonstrate that not only the tracking accuracy is guaranteed, but also the proposed control method can also successfully reduce the consumption of the onboard flight control unit’s computing resources.

This work investigates the control technique for a quadrotor unmanned aerial vehicle with a slung load. By taking the advantage of the cascade property, a new hierarchical control scheme is designed that divides the control problem into three parts. For the attitude motion control of the quadrotor, the non-singularity terminal sliding mode based control law is proposed. For the translation motion control of the quadrotor, the super-twisting based control law is designed. Additional, for the swing attenuation of the slung load, a nonlinear anti-swing control design is provided. A Lyapunov stability analysis is presented to show the stability of the closed loop system, together with the fast convergence of the quadrotor's translational and attitude tracking, and exponential convergence of the slung load's swing motion. The real time experiments verifies the well performance of the proposed controller.

This article focuses on the position and attitude tracking control design for an underactuated small-size unmanned helicopter. Considering the modelling uncertainties and the unknown external disturbances associated with the small-size unmanned helicopter, a new geometry-based adaptive tracking controller on special orthogonal group (SO(3)) is developed. To overcome the singularity and ambiguous issue inherented in the Euler angle expression and quaternion expression, the small-size unmanned helicopter’s dynamics is established on SO(3). Then, by using the sliding observer and radial basis function-based neural networks (RBFNNs), the helicopter’s dynamic modelling uncertainties and the unknown external disturbances are compensated. The stability of the closed-loop system is proved via the Lyapunov-based stability analysis. Moreover, the effectiveness of the proposed control strategy is verified on the self-made hardware-in-loop (HIL) testbed, and the experimental results show high position and attitude tracking accuracy of helicopter and the strong robustness to the unknown external disturbances.

This article presents a novel adaptive controller for a small-size unmanned helicopter using the reinforcement learning (RL) control methodology. The helicopter is subject to system uncertainties and unknown external disturbances. The dynamic unmodeling uncertainties of the system are estimated online by the actor network, and the tracking performance function is optimized via the critic network. The estimation error of the actor-critic network and the external unknown disturbances are compensated via the nonlinear robust component based on the sliding mode control method. The stability of the closed-loop system and the asymptotic convergence of the attitude tracking error are proved via the Lyapunov-based stability analysis. Finally, real-time experiments are performed on a helicopter control testbed. The experimental results show that the proposed controller achieves good control performance.

This paper presents a fault-tolerant control strategy to deal with the rear servo's stuck fault together with unknown exogenous disturbances of a trirotor unmanned aerial vehicle. A supertwisting-based observer is utilized to estimate the rear servo's stuck fault which is unknown, and a robust integral of the signum of the error based fault-tolerant controller is designed to compensate for the observation errors and exogenous disturbances. To avoid the singularity associated with orientation representations, the unit quaternion is utilized to formulate the attitude controller. The composite stability is analyzed via the Lyapunov-based methodology. Real-time experiments are implemented on a self-built hardware-in-loop-simulation trirotor testbed and the contrast experimental results with the sliding-mode-based fault-tolerant controller show that the proposed control scheme has achieved better control performance under the rear servo's stuck fault.

In this paper, we propose a hybrid FUZZY P + ID controller to stabilize the towing cable tension between a cable ship and a burying system. First, we develop the model of a winch system driven by valve-controlled hydraulic motors and evaluate the step responses yielded by the conventional PID and the proposed FUZZY P+ID controllers using simulations. The comparative studies show that the control performance yielded by the FUZZY P+ID controller is superior. We replace the existing PID controller implemented on the towing winch with the FUZZY P + ID controller for burying cable tasks at speed up to 1 knot under sea waves with significant variations (peak-to-peak) from 1.5 to 2.5 meters. The real applications demonstrate that the FUZZY P + ID controller is much more robust than the conventional PID controller.

In this paper, a quaternion based nonlinear output feedback tracking controller is developed to address the attitude and altitude tracking problem of a quadrotor unmanned aerial vehicle (UAV) which is subject to structural uncertainties and unknown external disturbances. A set of filters are introduced to provide estimation for the unmeasurable quadrotor UAV's angular and translational velocity signals. The Lyapunov based stability analysis ensures that a semi-global asymptotic tracking result is achieved and all closed loop states remain bounded with a suitable choice of control gains.

In this paper, the tracking control of a underactuated quadrotor aerial vehicle is presented where position and yaw trajectory tracking is achieved using feedback control system. The control design is complicated by considering parametric uncertainty in the dynamic modeling of the quadrotor aerial-robot. Robust control schemes are then designed using a Lyapunov-based approach to compensate for the unknown parameters in each dynamic subsystem model. Lyapunov-type stability analysis suggests a global uniform ultimately bounded (GUUB) tracking result.

In this paper, we consider the problem of task-space tracking control of robot manipulators. Based on a quaternion representation of the end-effector orientation, we design a class of task-space controllers that ensure asymptotic end-effector position and orientation tracking. To facilitate the control design, we first develop model-based and adaptive full-state feedback controllers. We then present a model-based output feedback controller that eliminates link velocity measurements via a model-based observer. The application of the proposed control strategy to redundant robots is also discussed. Simulation results based on a six-link manipulator system are presented for the output feedback controller.