Digital Motion Control And Its Application to
Camshaft Turning
Tsu-Chin Tsao
Associate Professor
University of Illinois at Urbana-Champaign
Department of Mechanical And Industrial Engineering
Non-Circular Turning Process for automotive camshaft
machining can potentially reduce or replace the present grinding process
with many benefits. It presents a challenging motion control problem
where a fast response linear
actuator carrying the cutting tool must generate a cam lobe profile precisely
in synchronization with a rotating workpiece and subject to cutting force
disturbances. Digital motion control algorithms for an electrohydraulic
actuator will be presented for this task. Because of the large range of
motion required, the nonlinear behavior of the hydraulic actuator must be
accounted for to ensure stability and tracking performance. Exploiting the
problem's special characteristics, a successive linearization approach,
which combines periodic system identification, robust performance linear
feedback, off-line repetitive control for feedforward input generation, and
on-line periodic time varying repetitive control is developed to achieve the
performance objective. Control issues and solutions of using another
actuator -- voice coil motor will also be presented if time permits.