Research And Implementation Of Control Method For Small Size Unmanned Helicopters

Small unmanned helicopter has high sensitivity and accuracy. It can vertically takeoff,landing, can take off without transmitting system, can fly with various attitude and speed.Owing to these advantages, helicopters are widely used in military and civil domains.The main purpose of this paper is to research control method of small unmannedhelicopter. This paper designs a partial linear method to calibrate the swashplate of a CCPMhelicopter. Meanwhile, by analyzing the helicopter’s height, attitude, position, heading, windfield and other status, several methods are designed, including identifying method of attitudemedian and dead zone, the control method with multi-channel coupling and the controlmethod in the wind field.The main work and research results are summarized as follows:(1) The aerodynamic characteristics of helicopter are studied. This paper focuses on howthe collective pitch angle, elevator angle and aileron affect the flying quality of helicopter.Then, the six degrees freedom model of helicopter is introduced.(2)With CCPM helicopter working principle, a partial linear method is designed tocalibrate the swashplate. The method is, through a calibration matrix, the servo signal and arotor wheel angle conversion calculation can be realized. This partial linear calibrationmethod has small error, and an automatic calibration system of swashplate has been achieved.(3) Attitude median and dead zone for hovering are identified in this paper. During theflight of helicopter, there exists nonlinear relationship between the attitude angle and theacceleration of the fuselage, including dead zone. By analyzing the relationships between theelevator angle and the longitudinal acceleration, the aileron angle and the horizontalacceleration, a method to identify the attitude median for hovering and the dead zone isproposed. And hysteresis loop between acceleration and attitude angle is confirmed. (4) This paper designs a control method aiming to eliminate the coupling effect amongattitude angles of the helicopter. During a flight of helicopter, the vertical accelerationdepends partly on the elevator and aileron angle, resulting in the ups and downs of helicopter.The relationship between the collective pitch angle and vertical acceleration is analyzed indetail, and a method to make compensation on collective pitch angle timely corresponding tothe elevator and aileron angle is accomplished. In order to assess this collective pitch anglecompensation method, this paper designs some simulation experiments.(5) The control method with wind influence is analyzed. Wind has complex influence tothe helicopter flight. After verifying that there exists approximate linear relationship betweenthe collective pitch angle and vertical acceleration, through distinguishing the relationshipbetween collective pitch angle and vertical acceleration, a method to monitor the windinfluence is designed. This paper mainly aims at eliminating the influence of horizontal andstable wind.All data of this paper comes from Align700E and Align600E autonomous flight controlplatform in real-time control and inter-operation lab. Applying the research results of thispaper improves the stability and accuracy of the helicopter flight control.