Combined Feedback and Feedforward Control for an Inertial Stabilization System

2013 ◽  
Vol 415 ◽  
pp. 101-108
Author(s):  
Kritsanun Malithong ◽  
Viboon Sangveraphunsiri
Keyword(s):  
Disturbance Rejection ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Design Procedure ◽  
Stabilization System ◽  
Model Uncertainties ◽  
Configuration Change ◽  
Aerial Vehicle ◽  
The Impact ◽  
Disturbance Torque

This paper presents environmental disturbance rejection in a 2-DOF inertial stabilization system by a combination of feedback and feedforward control. For feedback control, sliding mode control and the line of sight (LOS) stabilization are used for compensation of the nonlinearities, model uncertainties, friction and disturbances from outside environment. Although our mechanisms are carefully designed with statically balance, the center of the gravity will changed due to the configuration change during moving of the gimbal relative to an aerial vehicle. The disturbance torque from unbalance mass and gimbal geometry is unavoidable under the effect of the vibration of the aerial vehicle, which will lead to degrade the systems accuracy. Since the acceleration of the aerial carrier, due to the disturbance torque, can be measured, a feedforward disturbance rejection can be generated to compensate the disturbance torque. The experimental results confirm the validity of the control design procedure for the two-axis gimbaled stabilization system. The proposed controller is capable enough to overcome the disturbances and the impact of LOS disturbances on the tracking performance.

Vibration Rejection and Stabilization Control for an Inertial Stabilization System

2014 ◽  
Vol 619 ◽  
pp. 273-277
Author(s):  
Viboon Sangveraphunsiri ◽  
Kritsanun Malithong
Keyword(s):  
Disturbance Rejection ◽  
Pitch Angle ◽  
Controller Design ◽  
Sliding Mode ◽  
Line Of Sight ◽  
Stabilization System ◽  
Stabilization Control ◽  
Aerial Vehicle ◽  
Reference Input ◽  
Disturbance Torque

This paper presents a controller design of a 2-DOF inertial stabilization system. The line of sight (LOS) stabilization and sliding mode control are used for compensation of the nonlinearities and disturbances from the environment. And it proposes an acceleration feedforward for solving the unbalance torque. The disturbance torque from unbalance mass of gimbal structure is unavoidable under the effect of the vibration of the aerial vehicle. Since the acceleration of the aerial carrier can be measured, a feedforward disturbance rejection can be generated to compensate the disturbance torque. The experimental results demonstrate the performance of the controller, the disturbance is in the form of shaking the base's gimbal. The controller can track the reference input in the elevation axis and reject the base rate disturbance while maintaining its LOS direction. The error of pitch angle less than 0.02 rad, so the camera can track a specified point on an object.

scholarly journals Handling Model and Implementation Uncertainties via an Adaptive Discrete Sliding Mode Controller Design

2016 ◽  
Author(s):  
Mohammad Reza Amini ◽  
Mahdi Shahbakhti ◽  
Selina Pan ◽  
J. Karl Hedrick
Keyword(s):  
Adaptive Control ◽  
Controller Design ◽  
Sliding Mode ◽  
Electronic Control Unit ◽  
Control Technique ◽  
Propagation Mechanism ◽  
Sliding Mode Controller ◽  
Model Uncertainties ◽  
Control Approach ◽  
The Impact

Analog-to-digital conversion (ADC) and uncertainties in modeling the plant dynamics are the main sources of imprecisions in the design cycle of model-based controllers. These implementation and model uncertainties should be addressed in the early stages of the controller design, otherwise they could lead to failure in the controller performance and consequently increase the time and cost required for completing the controller verification and validation (V&V) with more iterative loops. In this paper, a new control approach is developed based on a nonlinear discrete sliding mode controller (DSMC) formulation to mitigate the ADC imprecisions and model uncertainties. To this end, a DSMC design is developed against implementation imprecisions by incorporating the knowledge of ADC uncertainties on control inputs via an online uncertainty prediction and propagation mechanism. Next, a generic online adaptive law will be derived to compensate for the impact of an unknown parameter in the controller equations that is assumed to represent the model uncertainty. The final proposed controller is an integrated adaptive DSMC with robustness to implementation and model uncertainties that includes (i) an online ADC uncertainty mechanism, and (ii) an online adaptation law. The proposed adaptive control approach is evaluated on a nonlinear automotive engine control problem in real-time using a processor-in-the-loop (PIL) setup with an actual electronic control unit (ECU). The results reveal that the proposed adaptive control technique removes the uncertainty in the model fast, and significantly improves the robustness of the controllers to ADC imprecisions. This provides up to 60% improvement in the performance of the controller under implementation and model uncertainties compared to a baseline DSMC, in which there are no incorporated ADC imprecisions.

scholarly journals Design of the impact controlling structure applying conventional digital control laws

2005 ◽  
Vol 18 (3) ◽  
pp. 361-377
Author(s):  
Milic Stojic ◽  
Milan Matijevic
Keyword(s):  
Digital Control ◽  
Disturbance Rejection ◽  
Internal Model ◽  
Design Procedure ◽  
Experimental Setup ◽  
External Disturbances ◽  
Control Laws ◽  
Internal Model Principle ◽  
And Control ◽  
The Impact

The design of a simplified IMPACT (Internal Model Principle and Control Together) structure comprising conventional digital control laws is presented. The design procedure is accomplished to enable the extraction of a known class of immeasurable external disturbances and easy setting of the controller parameters. In the proposed controlling structure, the set point transient response and speed of disturbance rejection can be adjusted independently. The efficiency and robustness of the proposed controlling structure are verified and tested by the simulation and experimental setup.

Robust Perfect Tracking Control With Discrete Sliding Mode Controller

2003 ◽  
Vol 125 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Jian Wang ◽  
Hendrik Van Brussel ◽  
Jan Swevers
Keyword(s):  
Transfer Function ◽  
Closed Loop ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Sliding Mode Controller ◽  
Model Uncertainties ◽  
Plant Model ◽  
Loop Transfer Function ◽  
Tracking Controllers ◽  
Switching Line

The closed-loop transfer function of a plant controlled with a classical feedback controller, depends on the dynamics of the plant. Since most feedforward tracking controllers are designed based on this closed-loop transfer function, they are not robust against plant model uncertainties. Sliding-mode controllers have the property that when the system is on the switching line, the closed-loop behavior is independent of the plant dynamics. As a result, it can be expected that a feedforward control design based on this closed-loop behavior is robust against plant model uncertainties. This paper studies this feedforward robustness issue in detail and verifies the results on an experimental test setup: a stage driven by a linear motor. An integrated procedure is proposed in designing the closed-loop discrete-time sliding mode controller using the reaching law method.

scholarly journals A new fault diagnosis and fault-tolerant control method for mechanical and aeronautical systems with neural estimators

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401989165 ◽  
Author(s):  
Haiying Qi ◽  
Yiran Shi ◽  
Yantao Tian ◽  
Clifford Mayhew ◽  
Ding-Li Yu ◽  
...  
Keyword(s):  
Control Method ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Design Procedure ◽  
Fault Tolerant Control ◽  
System Stability ◽  
Time Varying ◽  
Neural Network Learning ◽  
Control Loops ◽  
The Impact

A new method of fault detection and fault-tolerant control is proposed in this article for mechanical systems and aeronautical systems. The faults to be estimated and diagnosed are malfunctions that occurred within the control loops of the systems, rather than some static faults, such as gearbox fault, component cracks, and so on. In the proposed method, two neural networks are used as online estimators, the fault will be accurately estimated when the estimators are adapted online with the post-fault dynamic information. Furthermore, the estimated values of faults are used to compensate for the impact of the faults, so that the stability and performance of the system with the faults are maintained until the faulty components to be repaired. The sliding mode control is used to maintain system stability under the post-fault dynamics. The control law and the neural network learning algorithms are derived using the Lyapunov method, so that the neural estimators are guaranteed to converge to the fault to be diagnosed, while the entire closed-loop system stability is guaranteed with all variables bounded. The main contribution of this article to the knowledge in this field is that the proposed method can not only diagnose and tolerant with constant fault but also diagnose and tolerant with the time-varying faults. This is very important because most faults occurred in industrial systems are time varying in nature. A simulation example is used to demonstrate the design procedure and the effectiveness of the method. The simulation results are compared with the two existing methods that can cope with constant faults only, and the superiority is demonstrated.

scholarly journals Disturbance Rejection Attitude Control for a Quadrotor: Theory and Experiment

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Li Ding ◽  
Qing He ◽  
Chengjun Wang ◽  
Rongzhi Qi
Keyword(s):  
Attitude Control ◽  
Disturbance Rejection ◽  
Sliding Mode ◽  
External Disturbances ◽  
Attitude Tracking ◽  
Control Scheme ◽  
Aerial Vehicle ◽  
Linear Extended State Observer ◽  
The Stability ◽  
Theory And Experiment

In this article, an attitude tracking controller is designed for a quadrotor unmanned aerial vehicle (UAV) subject to lumped disturbances. Firstly, the attitude dynamical model of the quadrotor under external disturbances is established. Subsequently, an improved sliding mode control (SMC) strategy is designed based on the linear extended state observer (LESO). In this control scheme, the SMC will guarantee the sliding surface is finite time reachable and the LESO will estimate and compensate for the lumped disturbances. Then, the robustness and asymptotic stability of the proposed controller are proved by the stability analyses. Finally, three numerical simulation cases and comparative flight experiments validate the effectiveness of the developed controller.

scholarly journals Disturbance Rejection Trajectory Tracking Control for an Unmanned Quadrotor Based on Hybrid Controllers

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xiaoming Ji ◽  
Zihui Cai
Keyword(s):  
Trajectory Tracking ◽  
Disturbance Rejection ◽  
Tracking Control ◽  
Sliding Mode ◽  
Experimental Tests ◽  
Euler Method ◽  
Trajectory Tracking Control ◽  
Hybrid Controller ◽  
Active Disturbance Rejection ◽  
Aerial Vehicle

The purpose of this article is to explore a dual-loop problem regarding the trajectory tracking control of a quadrotor unmanned aerial vehicle, applying a linear active disturbance rejection and conditional integrator sliding mode controller, namely, LARC-CISMC. The quadrotor system model is derived through Newton–Euler method and consists of two subsystems. The hybrid controller for position and attitude loops is constructed. An evaluation of the proposed controller is presented in comparison with the linear active disturbance rejection controller. Simulation comparisons and experimental tests illustrate that the proposed controller has a satisfied robustness and accuracy under lumped disturbances.

scholarly journals Variable Structure Disturbance Rejection Control for Nonlinear Uncertain Systems with State and Control Delays via Optimal Sliding Mode Surface Approach

2013 ◽  
Vol 2013 ◽  
pp. 1-16
Author(s):  
Jing Lei ◽  
Xin Wang ◽  
Yu-Mei She ◽  
Tian-Jun Zhang
Keyword(s):  
Disturbance Rejection ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Variable Structure ◽  
Delay System ◽  
The State ◽  
Surface Approach ◽  
Disturbance Rejection Control ◽  
And Control ◽  
Control Delays

The paper considers the problem of variable structure control for nonlinear systems with uncertainty and time delays under persistent disturbance by using the optimal sliding mode surface approach. Through functional transformation, the original time-delay system is transformed into a delay-free one. The approximating sequence method is applied to solve the nonlinear optimal sliding mode surface problem which is reduced to a linear two-point boundary value problem of approximating sequences. The optimal sliding mode surface is obtained from the convergent solutions by solving a Riccati equation, a Sylvester equation, and the state and adjoint vector differential equations of approximating sequences. Then, the variable structure disturbance rejection control is presented by adopting an exponential trending law, where the state and control memory terms are designed to compensate the state and control delays, a feedforward control term is designed to reject the disturbance, and an adjoint compensator is designed to compensate the effects generated by the nonlinearity and the uncertainty. Furthermore, an observer is constructed to make the feedforward term physically realizable, and thus the dynamical observer-based dynamical variable structure disturbance rejection control law is produced. Finally, simulations are demonstrated to verify the effectiveness of the presented controller and the simplicity of the proposed approach.

scholarly journals Robust fault diagnosis and fault-tolerant control for nonlinear quadrotor unmanned aerial vehicle system with unknown actuator faults

2021 ◽  
Vol 18 (2) ◽  
pp. 172988142110027
Author(s):  
Jinjin Guo ◽  
Juntong Qi ◽  
Chong Wu
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Small Amplitude ◽  
Fault Tolerant ◽  
Sliding Mode ◽  
Adaptive Observer ◽  
Fault Estimation ◽  
Detection Accuracy ◽  
Actuator Faults ◽  
Model Uncertainties ◽  
Aerial Vehicle

This article addresses the problem that quadrotor unmanned aerial vehicle (UAV) actuator faults, including small-amplitude bias faults and gain degradation, cannot be detected in time. A hybrid observer, which combines the fast convergence from adaptive observer and the strong robustness from sliding mode observer, is proposed to detect and estimate UAV actuator faults accurately with model uncertainties and disturbances. A nonlinear quadrotor UAV model with model uncertainties and disturbances is considered and a more precise unified expression for actuator faults that do not require knowing where the upper or lower bound is provided. The original system is decomposed into two subsystems by coordinate transformation to improve detection accuracy for small amplitude bias faults and avoid external influences. The hybrid observer is then designed to estimate subsystem states and faults with good stability by selecting a Lyapunov function. A fault-tolerant controller is obtained depending on fault estimation by compensating the normal controller (proportion integral differential [PID] controller). Several numerical simulations confirmed that unknown actuator faults can be accurately detected, estimated, and compensated for even under disturbance conditions.

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