12th January 2018 at 9:57 am #1333IFP Energies nouvellesCompetitor
Before we start our control design, there are a few points that I would like to discuss.
The first and most important one concerns the controller inputs. As far as I understand, after having chosen ‘Rotary Controller’ or ‘Linear Controller’, we are supposed to develop our controller inside the ‘WECCCOMP Controller’ block. When choosing ‘Rotary Controller’, only one measurement of float motion is available to the controller : its acceleration. This is not consistent with the benchmark description : the relative float (angular) position should be available as well (sensors include an accelerometer and a position sensor).
Could you please clarify this point?
IFPEN Team12th January 2018 at 1:31 pm #1334IFP Energies nouvellesCompetitor
An update with what I have found digging in the code:
– The control input ‘motor_pos_rot’ actually gives the float angular position (the relative pitch displacement to be more precise)
– The control input ‘float_accel_rot’ is not the float pitch acceleration. There is an conversion step in block ‘lin2rot conversion’ block, which is unnecessary as its input ‘float_accel’ is already the angular acceleration float. In my opinion, this is a bug which should be corrected.
Could you please confirm/infirm?
IFPEN Team1st February 2018 at 7:28 pm #1343Tom NathanOrganiser
Apologies for the delay in our response. We want to confirm that your statements on 1/12/18 are correct. (1) The ‘motor_pos_rot’ does provide the relative pitch displacement. (2) There was an unnecessary conversion step in the lin2rot conversion block. This conversion block was designed to correct the measured acceleration from the accelerometer attached to the Wavestar arm. This accelerometer will be used in the experimental portion of the competition to provide input to the controller. The WEC-Sim developers are working with Aalborg University to construct a sensor model for the accelerometer. As of now the conversion block has been removed and the ‘float_accel’ is the angular acceleration of the WEC as calculated by WEC-Sim. We will notify participants when the developers have included a sensor model for the accelerometer.
Please pull the latest version of the WECCCOMP WEC-Sim model from the Github website.
National Renewable Energy Laboratory
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