Diff: Processes/Motion/motion.cpp

Revision:

25:50805ef8c499

Child:

26:b16f1045108f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Processes/Motion/motion.cpp	Tue Apr 09 20:37:59 2013 +0000
@@ -0,0 +1,70 @@
+////////////////////////////////////////////////////////////////////////////////
+// Motion control unit
+////////////////////////////////////////////////////////////////////////////////
+// Takes current state of the robot and target waypoint,
+// calculates desired forward and angular velocities and requests those from the motor control layer.
+////////////////////////////////////////////////////////////////////////////////
+
+#include "motion.h"
+
+namespace motion
+{
+
+void motionlayer(void const *dummy)
+{
+    //TODO: current_waypoint global in AI layer
+    //TODO: threshold for deciding that the waypoint has been achieved
+    
+    // get target waypoint from AI
+    Waypoint target_waypoint = *AI::current_waypoint;
+    
+    // get current state from Kalman
+    State current_state = Kalman::getState();
+    
+    float delta_x = target_waypoint.x - current_state.x;
+    float delta_y = target_waypoint.y - current_state.y;
+    
+    float distance_err = sqrt(delta_x*delta_x + delta_y*delta_y);
+    
+    float angle_err = atan2(delta_y, delta_x);
+    
+    
+    // angular velocity controller
+    const float p_gain_av = 1.0; //TODO: tune
+    
+    const float max_av = PI; // radians per sec //TODO: tune
+    
+    // angle error [-pi, pi]
+    float angular_v = p_gain_av * angle_err;
+    
+    // constrain range
+    if (angular_v > max_av)
+        angular_v = max_av;
+    else if (angular_v < -max_av)
+        angular_v = -max_av;
+    
+    
+    // forward velocity controller
+    const float p_gain_fv = 1.0; //TODO: tune
+    
+    float max_fv = 1.0; // meters per sec //TODO: tune
+    const float angle_envelope_exponent = 8.0; //TODO: tune
+    
+    // control, distance_err in meters
+    float forward_v = p_gain_fv * distance_err;
+    
+    // control the forward velocity envelope based on angular error
+    max_fv = max_fv * pow(cos(angle_err/2), angle_envelope_exponent);
+    
+    // constrain range
+    if (forward_v > max_fv)
+        forward_v = max_fv;
+    else if (forward_v < -max_fv)
+        forward_v = -max_fv;
+    
+    //TODO: put into motor control
+    MotorControl::set_fwdcmd(forward_v);
+    MotorControl::set_thetacmd(angular_v);
+}
+
+} //namespace
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