Regbot balance details

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Getting to balance

The double-click balance function is tested on some robots.

The robots are not totally equal:

• The balance point varies by about 5 degrees.
• One robot has a line-sensor board that gives a more even weight distribution.
• The motor parameters vary.

The Robots are placed on all three wheels. This is the most challenging start position to get into balance.

The mission is

thread=1
  log=2:time=0.01
  topos=0,bal=1,vel=0.35:time=4.99
  bal=0:time=1.5

The robot should, with this mission, get back to the start position after achieving balance. The maximum allowed speed when in balance is set to 0.35 m/s.

• The first 1 second is the most interesting. The robot has to move between 10 and 20 cm to get into balance. It takes about 3-4 seconds to get back to the start position,
• The balance point is calibrated to be 0 degrees. At this angle, the robot leans forward to compensate for the heavy back end caused by the control PCB.
• The front end will hit the floor if the tilt angle gets above about 20 degrees.

26 Mille

• The robot tilt (fat red) starts at -32 degrees.
• At 10ms, the motor voltage (fat yellow) saturates at -9V, providing backwards acceleration to reach balance.
• The motor current (thin purple) gets up to about 2A.
• The tilt velocity (thin blue, called Gyro-y) increases as the robot gets closer to balance.
• The tilt gets positive after about 0.13 seconds, and the velocity starts to decrease.
• The position (dashed cyan) reaches its maximum of 16 cm after about 0.5 seconds.
• When the velocity is close to zero, there are very few encoder ticks, and the robot starts oscillating a bit to get a reasonable velocity feedback.

32 Signe

• Signe has the biggest start-angle, but avoids in this case to hit the floor with the front, but very close to the +20 degrees.

42 Aya

• The motor current starts at about 3A for this robot. This gives a fast acceleration.
• After 0.29 seconds, the front of the robot hits the floor. The Gyro signal (thin blue) goes fast to zero at this point.

• The mission stops after 5 seconds.
• The (dashed cyan) do not get back to zero within this time.
• It takes almost one second before the front hits the ground (at 22 degrees).

60 Birte

• Birte has the additional line-sensor board and, therefore, the lowest start angle.
• The balance point is almost symmetrical, i.e. the front will hit the floor at about +30 degrees.

72 Emilia