1 files changed, 36 insertions, 0 deletions
diff --git a/zumo/pid.cpp b/zumo/pid.cpp
new file mode 100644
index 0000000..594d136
--- /dev/null
+++ b/zumo/pid.cpp
@@ -0,0 +1,36 @@
+#include "pid.h"
+
+class PID {
+private:
+	float A0, A1, A2;
+	float error[3] = {0};
+	float dt = 0.010;
+	float output = 0;
+
+public:
+	PID(float P, float I, float D) {
+		A0 = P + I*dt + D/dt;
+		A1 = -P - 2*D/dt;
+		A2 = D/dt;
+	}
+
+	// https://en.wikipedia.org/wiki/PID_controller#Pseudocode
+	float iter(float current, float target) {
+		error[2] = error[1];
+		error[1] = error[0];
+		error[0] = target - current;
+		output = output + A0 * error[0] + A1 * error[1] + A2 * error[2];
+		return output;
+	}
+};
+
+PID speed_pid(0.1, 0.0, 0.0); // TODO: tune these (garbage values)
+PID steer_pid(0.1, 0.0, 0.0);
+PID speed_mod_pid(1, 1, 1);
+void apply_pid(dui_state_t* target, dui_state_t* current) {
+	current->speed = speed_pid.iter(current->speed, target->speed);
+	current->steer = steer_pid.iter(current->steer, target->steer);
+	// current->speed_mod = speed_mod_pid.iter(current->speed_mod, target->speed_mod);
+	current->speed_mod = target->speed_mod;
+}
+