Abstract:
A servo system includes multiple servo channels being driven by a common error signal. Each channel has a controller that receives an error signal and provides a drive signal to a driver. The servo channels are arranged serially, with a drive signal from one controller forming the error signal for a downstream controller. As a result, the downstream controller does not attempt to correct for phase error directly, but instead attempts to keep the upstream driver at or near its operational midpoint. The servo channels can be arranged in order of decreasing controller bandwidth, from fastest to slowest. In contrast with a parallel configuration, in which servo channels all simultaneously receive a common error signal, the serial configuration can allow each controller to use its full bandwidth, can eliminate crosstalk between servo channels, and can prevent saturation of upstream drive signals.
Abstract:
A servo system includes multiple servo channels being driven by a common error signal. Each channel has a controller that receives an error signal and provides a drive signal to a driver. The servo channels are arranged serially, with a drive signal from one controller forming the error signal for a downstream controller. As a result, the downstream controller does not attempt to correct for phase error directly, but instead attempts to keep the upstream driver at or near its operational midpoint. The servo channels can be arranged in order of decreasing controller bandwidth, from fastest to slowest. In contrast with a parallel configuration, in which servo channels all simultaneously receive a common error signal, the serial configuration can allow each controller to use its full bandwidth, can eliminate crosstalk between servo channels, and can prevent saturation of upstream drive signals.