CoM and CoP measurment disagrees

[thomasfla]

We believe the CoM estimation could be improved using force sensors. We detect differences of about 1cm from CoP and CoM in static. It is to note that this errors depends on the posture, so it may be related to wrong mass distribution model. We also detect a whole body mass difference between model and measurement. Another possible problem is a wrong calibration of the feet force-torque sensor (related to #3)

A result of a non coherent CoM to CoP quantities is a conflict in the controller making us have to prioritize with a lot of caution the Force and CoM tracking task weight.

[thomasfla]

Mass identification is being done by @cmastalli

Here are some measurements of the weight of the robot I took today with a 0.1Kg resolution scale:
Robot with green battery (old): 60.0Kg
Robot with blue battery (new): 58.3Kg
Robot without battery: 48.9Kg