Motion-processor chip set takes on brushed and brushless motors
-- EDN, January 6, 2000
Instead of using a larger, more-costly board-level product, you can now control both brushless and brushed servo motors from a two-device chip set. The MC2800 series from Performance Motion Devices (PMD) (Picture) gives you support for sinusoidal commutation of two- or three-phase brushless motors and velocity and positioning control for brushed motors. You provide the ICs with input parameters, such as desired position, velocity, and acceleration, as well as your desired motion profile-s-curve, trapezoidal, velocity contouring, or electronic gearing-and the chip set generates the corresponding trajectory.
Feedback inputs to the chip set come from incremental or absolute encoders; it accepts incremental-encoder feedback as fast as 5 megacounts/sec and absolute-encoder/resolver inputs as fast as 160 megacounts/sec. The venerable PID algorithm and filter is preprogrammed into the chip set, for feedforward velocity and acceleration control; servo position-error calculations use 32 bits for requisite accuracy.
The MC2800 series software is backward-compatible with earlier families from PMD and is available in the two-axis MC2820 and four-axis MC2840 configurations. The product comprises a 132-pin processor and a 100-pin logic device, and prices begin at $69 (OEM).
Performance Motion Devices, 1-781-674-9860, www.pmdcorp.com.
-by Bill Schweber
