1 files changed, 34 insertions, 0 deletions
diff --git a/zumo/pid.cpp b/zumo/pid.cpp
new file mode 100644
index 0000000..9bef08f
--- /dev/null
+++ b/zumo/pid.cpp
@@ -0,0 +1,34 @@
+#include "pid.h"
+
+PID::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 PID::iter(float target) {
+	error[2] = error[1];
+	error[1] = error[0];
+	error[0] = target - output;
+	output = output + A0 * error[0] + A1 * error[1] + A2 * error[2];
+	return output;
+}
+
+void PID::reset(float value) {
+	error[0] = 0.0;
+	error[1] = 0.0;
+	error[2] = 0.0;
+	output = value;
+}
+
+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(target->speed);
+	current->steer = steer_pid.iter(target->steer);
+	// current->speed_mod = speed_mod_pid.iter(current->speed_mod, target->speed_mod);
+	current->speed_mod = target->speed_mod;
+}
+