| Four-rotor aircraft has an irreplaceable role in many fields like exploration of dangerous terrain,aerial photography and cargo transportation.It becomes a new research direction in the world with the advantage of simple structure,low cost,wide application,easy operation and so on.Flight controller is the core component of the four-rotor aircraft,which is the key and difficult point in aircraft development.A perfect and stable flight controller plays a vital role in aircraft attitude control.This paper presents the design of four-rotor aircraft,the analysis of its feasibility and the designing of the hardware and software.Three aspects have been discussed as follows.1.Building the hardware experimental platform of Four-rotor aircraft.Selecting the corresponding hardware equipment according to the early design of the pre-implementation function.The hardware platform is mainly used for function debugging and final aircraft achieving.After the control chip receives the body attitude measured by attitude sensor and the remote transceiver module receives the body attitude required by operator: The motor speed signal has been outputted based on the control algorithm,and then the corresponding PWM signal has been generated.After that,the body attitude has been changed.2.Improving the traditional single-loop PID control algorithm and giving a new double-loop PID control algorithm.The angular velocity is used to replace the traditional single-loop PID algorithm to control the body attitude,which gives a better performance of double-loop PID control algorithm in control precision,responsiveness and compatibility.3.Optimizing the software system architecture.A FIR filter is designed to reduce the frame vibration interference which makes the angle obtained by the control algorithm reflect the current body attitude more accurately.On the premise that the system time-delay caused by the filter is acceptable,the workload has been reduced and the handling has been enhanced significantly. |
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