add fritzing diagrams

Author: RCmags

README.md

@@ -1,16 +1,34 @@
 # ServoFlappingControl
 This Arduino sketch is the servo controller for an RC ornithopter (Flapping MAV) powered and controlled by two servos. Each servo is connected to a wing and flapped independently.
 
+## How it works
 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. 
 
-<img src = "img/triangle-fmod.png" width = "70%">
+<p align="center">
+<img src = "/images/plot/triangle-fmod.png" width = "70%">
+</p>
 
 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 = "70%">
+<p align="center">
+<img src = "/images/plot/triangle-truncation.png" width = "70%">
+</p>
 
 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%">
+## Schematics
+__Nano__:
 
+<p align="center">
+<img src = "images/diagrams/nano/schematic-nano.png" width = "80%">
+</p>
+
+__ATTiny__:
+
+<p align="center">
+<img src = "images/diagrams/nano/schematic-attiny.png" width = "80%">
+</p>
+
+
+## Example
 See this video to watch the controller in operation: [servo controller](https://youtu.be/T6NfZD_iuEs)  

controller-nano/controller-nano.ino

@@ -1,8 +1,8 @@
 /*      CONSTANT     |    VALUE   |  UNIT  |   DESCRIPTION */
 /*=========================================================*/
 // 1.  Flapping waveform
-#define FREQ              2.8     // hz     // Wingbeat frequency [hz]. Use lowest frequency that achieves flight
-#define GAIN_WAVE         12.0              /* Triangle wave to square wave gain (truncation). 
+#define FREQ              3.1     // hz     // Wingbeat frequency [hz]. Use lowest frequency that achieves flight
+#define GAIN_WAVE         6.0              /* Triangle wave to square wave gain (truncation). 
                                                A larger gain makes the waveform become more square-like with more throttle */
 // 2. Control inputs [negate to reverse direction]
     // I. Base inputs:
@@ -18,14 +18,14 @@
 #define GAIN_ROLL_FM      0.0               // Roll: One wing falls faster than the other
 
 // 3. Servo trims 
-#define TRIM_LEFT         0       // us     // left  wing 
-#define TRIM_RIGHT        -60     // us     // right wing
+#define TRIM_LEFT         -80     // us     // left  wing 
+#define TRIM_RIGHT        50      // us     // right wing
 #define TRIM_TLEFT        0       // us     // left  tail
 #define TRIM_TRIGHT       50      // us     // right tail
 
 // 4. Pitching moment correction 
-#define PITCH_TRIM_X      200     // us     // Throttle PWM when trim reaches maximum value 
-#define PITCH_TRIM_Y      -350    // us     // Maximum pitch trim. Negate to reverse deflection
+#define PITCH_TRIM_X      250     // us     // Throttle PWM when trim reaches maximum value 
+#define PITCH_TRIM_Y      -35  v0    // us     // Maximum pitch trim. Negate to reverse deflection
 
 // 5. Low voltage cutoff [voltage divider]
 #define RESISTOR_1        67000   // ohm    // Resistor from ground -> middle