File content as of revision 25:50805ef8c499:

////////////////////////////////////////////////////////////////////////////////
// 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