 Such solution was already known for a long time before the original G. Haig publication.The most basic of these designs are manually operated, even though an optional electric motor or stepper motor (considered in Trott's original design) automates and improves the accuracy of tracking, while considerably reducing the likelihood of platform vibrations that could result from manipulating the device; i.e., manually advancing the drive rod.Reportedly, Dave Trott's two-arm Type 4 design can potentially reduce trailing error to 1 arc second per hour, allowing for very long trail-less exposures, even in combination with long (200mm +) lenses.