Lesson-5.markdown

@@ -300,21 +300,14 @@ Other similar tests could be performed to test how the environment(temperature,
 To test the robot and the different gains effect on the robot, as described in the setup, we tried to control the robot with one gain at a time:
 
 * **KGyroAngle**: Controlling the robot only with the gyro angle, was not possible. The problem encountered was that the angle drifted with time. In the beginning of the test, the angle was correctly 0 degrees when the robot was in an upright position, but during the test this changed to +5-10 degrees. This meant that the robot tried to maintain a position which was not upright, and therefore fell over. 
-* **KGyroSpeed**: The gyro speed did not drift in the same way as the angle and as a consequent the control using only the gyro speed was much better than the angle, although it was not sufficient for the robot to maintain balance.
+* **KGyroSpeed**: The gyro speed did not drift in the same way as the angle and as a consequent the control using only the gyro speed was much better than the angle, although it was not sufficient for the robot to maintain balance. Since this term becomes non-zero fast when the robot is falling, it causes the control to act faster than relying on the angle alone does.
 * **KSpeed**: The motor speed gain determines the resistance in the motor. The faster the wheel was spanned, the higher the resistance from the motor.
 * **KPos**: The motor position gain makes the wheel turn back to its original position. Increasing the gain increases the speed with which the motor turns back to the set-point. If increased to much, the motors starts oscillating.
 
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+A possible cause for the erroneous angle could be, that the gyro sensor is more sensitive in the forward direction than backwards, causing a small error on each gyrospeed calculation, which the integration of time then accumulates. 
 In the first test of the robot, the gyro sensor was placed on the shoulder of the robot. This gave rise to a lot of fluctuations in the gyro sensor data, due to the fact that robots upper part is very loosely connected to the lower part and therefore shakes a lot.
 In the second part, the gyro sensor was attached to the lower part of the robot. This removed a lot of the high fluctuations due to the tremors.
 
-Hvad vi har prøvet:
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-- Gyroangle                             -> Robotten reagere for langsomt
-- Afhjælpes med GyroSPeed Gain          -> Robotten reagere hurtigt, men den ved ikke hvad vinklen er
-- Sensoren har siddet to steder, først i toppen og dernæst længere nede -> Mindre rystelser, men også mindre udsving i vinklen.
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 ## Conclusion
 
 Bedre gyro -> Sensor fusion