Configure underspeed detection parameters.

Arguments:

Axes axes

The set of telescope axes to configure.

Double holdoff

The time (hours) that unexpectedly low speeds must persist, before an underspeed condition is signalled.

Double min_fract

The axis is considered underspeed when its speed is below this fraction of the commanded speed, for at least for holdoff seconds.

Double jitter

When the commanded speed is so low that its underspeed threshold speed is below this noise level (degrees/s), apparent underspeed conditions will be ignored.

Example:

The following example would tell the control system would configure the underspeed detection parameters of both the azimuth and elevation axes. It says that an underspeed condition should be declared whenever the actual speed of one of these axes is less than half its commanded speed for at least 5 seconds, provided that half the commanded speed is over a servo velocity jitter of 5 arcseconds/second,

underspeed_pars az+el, 0:0:5, 0.5, 0:0:5

Context:

The underspeed detection code attempts to detect any failure that causes a telescope axis to move much slower than expected. Such behavior could be caused by many forms of failure, such as a mechanical interference, motor commutation problems, encoder readout problems, a disconnected servo cable, or some failure in the hardware velocity servo.

An axis is deemed to be going unexpectedly slowly if its actual speed is less than a factor min_fact of the commanded velocity. To trigger an underspeed event, this condition must persist for at least holdoff seconds.

When the commanded speed of the telescope is so low that multiplying it by min_fact produces an underspeed threshold speed that is below the expected speed jitter of the servo, underspeed detection is disabled, to avoid false detections. The jitter argument allows one to specify the expected velocity jitter.