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Posted by Maksimuzz | Feb 22, 2018 @ 05:11 AM | 892 Views
The functional diagram of the autopilot is shown on a picture. The heart of the autopilot is the LEVEL1 block. This module is a high-priority function and is executed independently of other events every (15.625 ms tested version) 46.875 ms. Its task is to keep the aircraft in the correct flight position.
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The input data for the module is the FSSi structure, which contains the parameters Roll, Pitch and Air Speed. A correct flight position we will name roll = 0 and pitch = 0, when Ref signals are absent. Also this module controls the engine controller of the aircraft and ensures the holding of the speed received from the LEVEL2 unit in accordance with the flight task. The Level2 module disturbs the LEVEL1 module by the Ref signals and thus forces it to hold non-zero roll and pitch values that calculated in accordance with the flight task. The speed parameter is directly transmitted from the flight task. The output of the module is a data structure that contains the current position of ailerons, elevator, rudder and rudder (Throttle). This structure in the program is called FSSo, the Module has the name FltStSys (flight stabilization system). It can be fed into the PWMC (Pulse Wide Modulation Controller) if the autopilot mode is activated. Otherwise, a structure filled with a timer is sent to the PWMC according to the measured values received from the HF receiver. This is a traditional control mode for radio-controlled models. The Level2 module is slower, it generates...Continue Reading
Posted by Maksimuzz | Feb 12, 2018 @ 09:42 AM | 1,718 Views
1. Introduction
I started interest RC-planes at 2002 I made , when I had living in Prague. The first aircraft was with a wingspan of 1.2 m, engine 2-stroke ICE. Here is a fragment of a video recording of those times. Once in 2008, I got an accelerometer ADXL202E. Having experience developing devices on the MCS-51 family controller (it was Rubidium frequency standard and data acquisition system), I decided to make an autopilot for the Mentor radio controlled model. First of all, I connected the accelerometer to the controller. For simplicity, I chose a debug card with the AT91SAM7 controller, for the convenience and ease of handling it. It should be noted that I decided not to study anything about autopilots on the Internet, but to do everything myself with "0", so that it would be more interesting.
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So, by chance of the case in 2008, I happened to fly by plane and have the opportunity to use a laptop and my controller with an accelerometer on board. Today, any owner of a tablet or smartphone can carry out such an experiment independently, since accelerometers are available in almost all devices.
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Description: At board
That's where I made the first "discovery" for myself, that you can use the accelerometer to stabilize the pitch (since the aircraft cannot gain speed too fast or slow down), but for stabilizing the roll it is not good. Since with a correct turn without slip, the side accelerations are compensated by the aircraft's roll, and the accelerometer does...Continue Reading