PPA calibration refers to discovering and setting tuning factors for electromagnet timing. It is performed to:
- While the default calibration figures usually work well, in some cases, the default tuning factors need to be changed to get reliable rotation on your PPA, and/or
- Achieving highest possible speed operation of the PPA
Finding the best tuning factor for each IRPS is done by moving the throttle to adjust the tuning factor as the ball rotates. One tuning factor exists per IRPS (not per Electromagnet) according to the following definition:
Tuning Factor = pulse duration / deactivated transition time
where deactivated transition time is the time the ball would take to travel from the entry side of the electromagnet to the centre of the magnet if the electromagnet was disabled. Refer to the diagram in Personal Particle Accelerator.
The calibration user interface
The calibration user interface is a combination of using the red button and the throttle. The red button cycles through the different IRPS units. Press the red button until the IRPS unit of interest is highlighted. Then slide the throttle up or down to change the value. Note that the tuning factor changes with the relative movement of the throttle, rather than its absolute position.
It’s easy to get to the end of the throttle range. In this case, cycle the red button until an unused IRPS is selected (typically IRPS number zero). Then move the throttle to wherever needed, and press the red button again to continue tuning factor changes.
- setup the PPA and prepare to rotate
- attempt rotation. If self-sustaining rotation occurs, then use the user interface described above to seek the best speed, which is the optimal tuning factor. Write down the IRPS unit number and its best value. These values can then be updated in the firmware so that they don’t need to be reset next time the unit is powered up – further information will be provided in a forthcoming blog.
If self sustaining rotation doesn’t occur, then make a large adjustment to the tuning factor, and attempt rotation. This may need to be done for several IRPS to achieve self-sustaining rotation. Write down the IRPS unit number and its best value for later update to firmware. If self-sustaining rotation still doesn’t occur, review debugging.
Absolute limits have been imposed on tuning factor value. The green button is not used for the calibration function.