+static void update_pos(void) {
+ static int16_t pos1_last=0;
+ static int16_t pos2_last=0;
+ static int16_t pos3_last=0;
+ static int16_t pos4_last=0;
+ int16_t pos1_diff; // steps
+ int16_t pos2_diff;
+ int16_t pos3_diff;
+ int16_t pos4_diff;
+ float diff_left_m, diff_right_m, angle_diff, translation;
+ float pos_x_new, pos_y_new, angle_new;
+ int16_t speed_l, speed_r;
+ float tmp_speed_lin, tmp_speed_rot;
+ int16_t cur_pos1, cur_pos2, cur_pos3, cur_pos4;
+ int16_t new_speed1, new_speed2, new_speed3, new_speed4;
+
+ // copy to tmp
+ cli();
+ cur_pos1 = pos1;
+ cur_pos2 = pos2;
+ cur_pos3 = pos3;
+ cur_pos4 = pos4;
+ sei();
+
+ pos1_diff = cur_pos1 - pos1_last;
+ pos2_diff = cur_pos2 - pos2_last;
+ pos3_diff = cur_pos3 - pos3_last;
+ pos4_diff = cur_pos4 - pos4_last;
+
+ new_speed1 = pos1_diff/PID_T;
+ new_speed2 = pos2_diff/PID_T;
+ new_speed3 = pos3_diff/PID_T;
+ new_speed4 = pos4_diff/PID_T;
+
+ diff_left_m = (pos1_diff + pos2_diff)/(2*STEP_PER_M);
+ diff_right_m = (pos3_diff + pos4_diff)/(2*STEP_PER_M);
+ angle_diff = (diff_right_m - diff_left_m) / WHEEL_DIST;
+
+ angle_new = angle.f + angle_diff;
+ if (angle_new > 2*M_PI) angle_new-=2*M_PI;
+ else if (angle_new < 2*M_PI) angle_new+=2*M_PI;
+
+ translation = (diff_left_m + diff_right_m)/2.0;
+ pos_x_new = pos_x.f + cos(angle_new)*translation;
+ pos_y_new = pos_y.f + sin(angle_new)*translation;
+
+ speed_l = (new_speed1+new_speed2)/2;
+ speed_r = (new_speed3+new_speed4)/2;
+ tmp_speed_lin = (speed_l + speed_r)/(2.0*STEP_PER_M);
+ tmp_speed_rot = (speed_r - speed_l)/(M_PI*WHEEL_DIST*STEP_PER_M);
+
+ // copy from tmp
+ cli();
+ angle.f = angle_new;
+ pos_x.f = pos_x_new;
+ pos_y.f = pos_y_new;
+ speed1 = new_speed1;
+ speed2 = new_speed2;
+ speed3 = new_speed3;
+ speed4 = new_speed4;
+ cur_speed_lin = tmp_speed_lin;
+ cur_speed_rot = tmp_speed_rot;
+ sei();
+
+ pos1_last = cur_pos1;
+ pos2_last = cur_pos2;
+ pos3_last = cur_pos3;
+ pos4_last = cur_pos4;
+}