Abstract
The equations behind digital motion control are continually finding better calculation vehicles as microprocessors and DSP’s advance in performance and cost effectiveness. However solving a motion control application involves much more than timely execution of servo loops. There are many system level issues to be addressed. The system’s objective needs to be expressed in at least one and perhaps several motion application programs. Information from non-quadrature as well as quadrature sensors needs to be interpreted and used by the motion controller. Other controlled devices need to be coordinated with respect to motion events. The operator needs to communicate to the system to request and alter system actions.Many motion controller manufacturers respond to system level needs by making motion controllers more like computers. These motion controllers have the ability to run application programs, have IO buses that communicate to external hardware, and have serial ports that allow connection to operator interface terminals.
An alternative approach to making a motion controller more like a computer is to make a computer more like a motion controller. This paper describes an architecture based on a 386 PC which takes this second approach.
The following sections include an example problem, architecture description, problem solution, discussion of architecture contributions towards the solution, additional architecture benefits and a summary.
{This paper represents technology trends in the early 90's. Determinism issues under Windows NT and the demand for higher performance motion control solutions in the 250 microsecond sample period range made the described approach less viable. These advances motivated Douloi to change controller architecture to include a 128 MHz 486 processor right on the motion control card. This architecture change is described in a more recent paper, "Motion Server" - A Next Generation Motion Controller Architecture }