add frame

README.md

@@ -1,16 +1,32 @@
 # Arduino quadcopter
+A simple quadcopter filght controller designed to work in angle control mode ([diagram](https://docs.px4.io/v1.12/assets/img/mc_control_arch.21116ef0.jpg)).  
+All parameters are grouped in `config.h`.  
+Switch `OPERATING_MODE` to perform ESC calibration and IMU calibration.  
+Switch `DEBUG` to visualize print messages in the serial monitor.  
+The control loop frequency is about 80Hz.
 
-## Hardware
+## Software requirements
+Arduino libraries:
+- MPU9250==0.4.8
+- AutoPID==1.0.3
+
+## Hardware requirements
 - Board: Arduino Mega 2560
 - Imu: MPU 9250
 - Receiver: Flysky FS-IA6 
 - Motor/ESC: A2212 1000KV Brushless Motor 30A ESC 
 - Propeller: 1045
 - Rangefinder: HC-SR04
-- Battery: LiPo 2S 30C EC2 or LiPo 3S 35C XT60
+- Battery: LiPo 3S 35C XT60
 - DC/DC stepdown: LM7805
+- 30A fuse
 
-## Requirements
-- MPU9250==0.4.8
-- AutoPID==1.0.3
+## Frame
+- 4x motor.stl
+- 4x holder.stl
+- 4x hollow alluminium rod 10x10x130 mm (to link motor and holder)
+- 1x plastic disk diameter ~220 mm (the base where to anchor holders with 3M bolts)
+- 1x cover.stl
 
+![img](frame/top.jpg)
+![img](frame/bottom.jpg)

config.h

@@ -22,9 +22,6 @@
 #define BANGBANG 300
 #define TIMESTEP 10
 
-// Low pass filter
-#define LPFD 0.2
-
 // Pid config
 #define ROLL_PID_KP 1.1
 #define ROLL_PID_KI 0
@@ -46,6 +43,13 @@
 #define YAW_RATE_PID_KI 0
 #define YAW_RATE_PID_KD 0
 
+// Angular rate low pass filter coefficient
+#define LPFD 0.2
+
+// Smooth fall
+#define SMOOTH_FALL_DIST 10
+#define SMOOTH_FALL_PWM 1350
+
 // Motor pins
 #define PIN_MOTOR_0 6
 #define PIN_MOTOR_1 3

flight_control.cpp

@@ -1,3 +1,4 @@
+#include "Servo.h"
 #include "Arduino.h"
 #include "AutoPID.h"
 #include "flight_control.h"
@@ -81,11 +82,11 @@ void control_loop() {
     PID_roll_rate.run();
     PID_pitch_rate.run();
     PID_yaw_rate.run();
-    // Slow fall from higher than 10cm
-    if (ground_dist > 10 && ground_dist < 400)
-      throttle = max(throttle, 1300);
+    // Prevent free fall from more than 10cm
+    if (ground_dist > SMOOTH_FALL_DIST && ground_dist < 400)
+      throttle = max(throttle, SMOOTH_FALL_PWM);
     // Thrust correction by attitude
-    throttle = 1000 + ((float)(throttle - 1000)) / (cos(angles.roll * DEG_TO_RAD) * cos(angles.pitch * DEG_TO_RAD));
+    throttle = MIN_PULSE_LENGTH + ((float)(throttle - MIN_PULSE_LENGTH)) / (cos(angles.roll * DEG_TO_RAD) * cos(angles.pitch * DEG_TO_RAD));
     // Mixer
     mixer_output[0] = throttle + (rates_output.roll) + (rates_output.pitch) + rates_output.yaw;
     mixer_output[1] = throttle - (rates_output.roll) + (rates_output.pitch) - rates_output.yaw;