How ServoWire Works ...

ServoWire creates an elegant, effective architecture for real-time servo control.

ServoWire uses IEEE-1394 to create a potent architecture for multi-axis motion control and synchronization. The system uses the 1394 memory mapped model where all drive setup and motion control parameters are defined as software variables and communicated in real-time over the IEEE-1394 bus.

Servo loops are managed in real-time over the bus, implementing a digital torque control network for up to 8 axes and eliminating all digital-to-analog conversions. Actual torque commands to the drives are transmitted digitally as 16 bit variables, eliminating the cost and limitations of traditional 12-bit, D-to-A converters and analog torque signals.

Digital torque control combines the fundamental advantages of torque-mode control (greater control flexibility, acceleration feedforward and torque information) with the advantages of digital networking and performance.  In this digital system, a velocity observer eliminates the need for an analog tachometer, and all potentiometers are eliminated by software parameters. All loop adjustments are automatically computed when a motor, load inertia and the velocity loop time constant are selected from a configuration software menu. System parameters such as "peak motor output torque" are also set in software.

With the complete elimination of analog conversions, the ServoWire drive network provides both high bandwidth and outstanding noise immunity. Digital servo loops (including 32-bit intermediate results on calculations) provide precise control algorithms that result in drift-free operation.  The user’s application program can easily adjust for changing factors (such as load inertia) by dynamically changing any of the drive settings or loop parameters. An all-software torque-mode positioning system also provides outstanding performance monitoring, with easily accessible real-time values for position, velocity, acceleration and torque.