readme

Author: RCmags

README.md

@@ -3,11 +3,17 @@ This Arduino sketch is the servo controller for an RC ornithopter (Flapping MAV)
 
 The program is designed to receive 4 PWM inputs from an RC receiver operating in [MODE 2](https://www.rc-airplane-world.com/rc-transmitter-modes.html) and outputs 4 PWM signals for off-the-shelft hobby servos. Two servos control the wings and two servos control a V-tail.
 
-The aileron (1) and elevator (2) channels are used to modify the motion of the wings and to control the tail. The dihedral angle of the wings is altered in unison with elevator, while the aileron rotates them in opposite directions. Simultaneously, the frequency of the wing-oscillation can be modulated, such that the wings move faster during the downstroke or during the uptroke. Depending on whether this is done symmetrically or assymetrically, one can obtain pitch or roll control. At the same time, the throttle channel (3) control the amplitude of a fixed-frequency oscillation, while the rudder channel (4) assymetrically varies the amplitude of the wings. 
+The aileron (1) and elevator (2) channels are used to modify the motion of the wings and to control the tail. The dihedral angle of the wings is altered in unison with elevator, while the aileron rotates them in opposite directions. Simultaneously, the frequency of the wing-oscillation can be modulated, such that the wings move faster during the downstroke or during the uptroke. Depending on whether this is done symmetrically or assymetrically, one can obtain pitch or roll control. 
 
-The program was written for an Arduino Nano but it should be compatible with other boards. See the attached schematic for an example of the required circuit:
+<img src = "img/triangle-freq-mod.png" width = "50%">
 
-<img src = "schematic.png" width = "80%">
+The throttle channel (3) control the amplitude of a fixed-frequency oscillation. By the default, the waveform is a triangle-wave, but the throttle can also be used to trucante the wave so it looks more like a square wave. Using a square wave allows the servo to output more mechanical power, but the transition between strokes is abrupt. The truncated-wave eases this transition.
+
+<img src = "img/triangle-truncation.png" width = "50%">
+
+Lastly, rudder channel (4) is used to assymetrically vary the amplitude of the wings. While the program was written for an Arduino Nano but it should be compatible with other boards. See the attached schematic for an example of the required circuit:
+
+<img src = "img/schematic.png" width = "80%">
 
 This video shows what the does controller and how it works:  
 [<img src="https://img.youtube.com/vi/T6NfZD_iuEs/maxresdefault.jpg" width="50%">](https://youtu.be/T6NfZD_iuEs)