Unit vector approach based sliding mode control of a small-scale unmanned helicopter

2010 ◽  
Author(s):  
Hamid Hajkarami ◽  
Mohammad Saleh Ahmadi ◽  
Mohammad Danesh
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Unit Vector ◽  
Small Scale ◽  
Unmanned Helicopter ◽  
Mode Control ◽  
Vector Approach

scholarly journals Autopilot Design for a Compound Control Small-Scale Solid Rocket in the Initial Stage of Launch

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Tian Dong ◽  
Changjian Zhao ◽  
Zhiguo Song
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
System Stability ◽  
Small Scale ◽  
Control Law ◽  
Rolling Moment ◽  
Mode Control ◽  
Compound Control ◽  
Initial Stage ◽  
Solid Rocket

In this paper, an autopilot design method for a compound control small-scale solid rocket is proposed. The rocket has multiple actuators, including a flexible nozzle for pitching and yawing channels, aerodynamic fins for rolling channel, and lateral thrusters which work in on-off mode for all three channels. In order to keep the aircraft steady in the initial stage of launch when the dynamic pressure is low, the autopilot is aimed at optimizing the cooperation among the actuators. Firstly, without considering the discontinuous lateral thrust, the control law for flexible nozzle and aerodynamic fins is achieved via the sliding mode control approach. On this basis, an object to be controlled with choiceness is obtained for the lateral thrusters controlled loop. Secondly, the operation logic of lateral thrusters is programmed, regarding rolling moment as priority. Thirdly, after a continuous controller is obtained, a discretization method for the lateral thrusters control law is designed combining the characteristics of sliding mode control and Lyapunov’s stableness theorem. Finally, the fundamental cause why compound control improves the system stability is given theoretically. Simulation results validate the improved response performance and robustness against uncertainties and disturbance of the autopilot.

scholarly journals Trajectory Tracking Control for Small-Scale Unmanned Helicopters with Mismatched Disturbances Based on a Continuous Sliding Mode Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Xing Fang ◽  
Yujia Shang
Keyword(s):  
Sliding Mode Control ◽  
Disturbance Rejection ◽  
Tracking Control ◽  
Closed Loop ◽  
Sliding Mode ◽  
Small Scale ◽  
Control Law ◽  
Trajectory Tracking Control ◽  
Mode Control ◽  
Mismatched Disturbances

A novel continuous sliding mode control (CSMC) strategy based on the finite-time disturbance observer (FTDO) is proposed for the small-scale unmanned helicopters in the presence of both matched and mismatched disturbances. First, a novel sliding surface is designed based on the estimates of the mismatched disturbances and their derivatives obtained by the FTDO. Then, a continuous sliding mode control law is developed, which does not lead to any chattering phenomenon. Furthermore, the closed-loop helicopter system is proved to be asymptotically stable. Finally, the excellent hovering and tracking performance, as well as the powerful disturbance rejection capability of the proposed novel CSMC method, is validated by the simulation results.

scholarly journals Sliding Mode Control of Magnetic Bearings: Comparison of Sensed and Self Sensing Performance

1999 ◽  
Author(s):  
S. Ueno ◽  
J. H. Lee ◽  
P. E. Allaire ◽  
Y. Okada
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Angular Displacement ◽  
State Space Model ◽  
Experimental Results ◽  
Magnetic Bearings ◽  
Small Scale ◽  
Linear Component ◽  
Mode Control ◽  
Physical Sensors

A sliding mode control algorithm has been designed for control of a balance beam on two symmetric magnetic bearings. A state space model of the system is developed and the controller is separated into a linear and non-linear component. A reaching condition to bring the system to the sliding surface is developed and a continuous function boundary layer approach is evaluated to avoid chattering. Previous works have discussed theoretical and experimental sliding mode control with physical sensors. This paper represents the first use of a simple envelope filter for sliding mode self sensing. The system simulation demonstrates arrival at the hyperplane surface within 0.003 sec and converges to the zero angular displacement value within 0.008 sec. Experimental results produced system convergence to zero angular displacement within approximately 0.35 sec both for the case when an eddy current position sensor was used and the case when system self sensing was employed. Some small scale chatter was observed in the experimental results with a peak to peak magnitude of approximately 3 times larger in the self-sensing case as compared to the case with a physical sensor.

Multiloop state-dependent nonlinear time-varying sliding mode control of unmanned small-scale helicopter

2019 ◽  
Vol 234 (3) ◽  
pp. 585-606 ◽  
Author(s):  
Sinan Ozcan ◽  
Metin U Salamci ◽  
Volkan Nalbantoglu
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Operating Conditions ◽  
Small Scale ◽  
Time Varying ◽  
Parameter Uncertainties ◽  
Time Step ◽  
Mode Control ◽  
State Dependent ◽  
Improved Performance

Time delays, parameter uncertainties, and disturbances are the fundamental problems that hinder the stability and reduce dramatically the tracking performance of dynamical systems. In this paper, a new state-dependent nonlinear time-varying sliding mode control autopilot structure is proposed to cope with these dynamical and environmental complexities for an unmanned helicopter. The presented technique is based on freezing the nonlinear system equations on each time step and designing a controller using the frozen system model at this time step. The proposed method offers an improved performance in the presence of major disturbances and parameter uncertainties by adapting itself to possible dynamical varieties without a need of trimming the system on different operating conditions. Unlike the existing linear cascade autopilot structure, this study also proposes a nonlinear cascade state-dependent coefficient helicopter autopilot structure consisting of four separate nonlinear sub-systems. The proposed method is tested through the real time and PC-based simulations. To show the performance of the proposed robust method, it is also bench-marked against a linear sliding control control in PC-based simulations.

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