NAME¶

ilowpass - Low-pass filter with integer inputs and outputs

SYNOPSIS¶

loadrt ilowpass [count=N|names=name1[,name2...]]

DESCRIPTION¶

While it may find other applications, this component was written to create smoother motion while jogging with an MPG.

In a machine with high acceleration, a short jog can behave almost like a step function. By putting the ilowpass component between the MPG encoder counts output and the axis jog-counts input, this can be smoothed.

Choose scale conservatively so that during a single session there will never be more than about 2e9/scale pulses seen on the MPG. Choose gain according to the smoothing level desired. Divide the axis.N.jog-scale values by scale.

FUNCTIONS¶

ilowpass.N (requires a floating-point thread)

Update the output based on the input and parameters.

PINS¶

ilowpass.N.in s32 in

ilowpass.N.out s32 out

out tracks in*scale through a low-pass filter of gain per period.

PARAMETERS¶

ilowpass.N.scale float rw (default: 1024)

A scale factor applied to the output value of the low-pass filter.

ilowpass.N.gain float rw (default: .5)

Together with the period, sets the rate at which the output changes. Useful range is between 0 and 1, with higher values causing the input value to be tracked more quickly. For instance, a setting of 0.9 causes the output value to go 90% of the way towards the input value in each period.

AUTHOR¶

Jeff Epler

LICENSE¶

GPL