Calibrating the SkyStopper controller for the mechanical dimensions
The electronic control on the SkyStopper compensates for the tangent arm geometry and precisely tracks the stars without requiring hand tuning. At the factory, the dimensions of the platform are stored into the controller, so that it will track precisely.
The dimensions required are:
The distance from the axis to the center of the drive rod.
The starting position of the carriage relative to the center of the drive rod.
The length of the magnetic linkage.
The distance from the axis to the center of the pedestal.
The distance between the feet on the base of the telescope.
The distance between the feet on the base of the platform
The scale factor applicable to the vertical actuator. In conjunction with the telescope feet, this allows conversion of steps to arcseconds.
In addition, there are flags to allow reversal of the motors and tracking in the southern hemisphere.
The programming is accomplished via the IR remote. The sequences are designed to be easy to do but require the entry of the parameters and (unpublished) magic numbers. The magic numbers prevent accidental re-programming of the dimensions, but allow factory entry without difficulty. The design parameters of the SkyStopper are used to determine the above parameter values. In some cases, the actual measured values suffice, such as the linkage length. The precision of the stored parameters is 0.01 mm but good tracking is achieved with much rougher measurements. In the case of adapting the SkyStopper controller to a legacy platform, the geometry data would have to be measured by the customer and input. Adapting to legacy controllers requires detailed analysis of the geometry of the tracking and motor circuits, and has not been attempted yet. Likely a software update will be required to handle each new kind of platform.