Positioner Control Systems
The Cobham Sensor Systems Largo control systems are software based digital controls tailored to the application by software modifications via the communications interface, provides operational commands, servo compensation, gain modifications, and commands peripheral sensors. Since the designs use PC-104 and VME formats, the controls reflect an open architecture that is upgradeable to prevent obsolescence.
The architecture utilizes Industrial Pack (IP) modules to implement a wide variety of interfaces and features including A/D and D/A converters, R/D converters, digital and analog I/O interfaces, IRIG timing, auto video track and communications interfaces like RS-422/232, RS-485, Ethernet, and other common COM formats. The controls form a common set for all Cobham Largo positioners and can be adapted to other positioners as well to implement upgrades, overhauls and modernization.
SPS-2722 Servo Digital Control Unit
The Servo Digital Control Unit (SDC) is a microprocessor-based, servo controller, providing both position and rate-loop control of the positioner. A firmware download that modifies digital compensation filters allows the servo-loop to be optimized for different payloads.
The SDC includes multiple RS-422/RS-232/RS485 and Ethernet ports to allow control of, and access to, the signals generated by sensors and monitoring equipment associated with the payload . Use with brushless, low-torque-ripple motors with Pulse-Width-Modulated (PWM) amplifiers provide rapid and precise control.
The SDC monitors servo faults and provides a number of safety features, which include the ability to prevent remote operation of the positioner while maintenance personnel are working on the unit.
The SDC is available for mounting in a 19-inch EIA rack, in a NEMA weatherproof enclosure or it can be custom packaged. The SDC can be commanded by an external computer system, joystick, or autotracker.
SPS-2702 Servo Amplifier Unit
The Servo Amplifier Unit (SAU) is used to provide power to the positioner without servo controls. It is used when the Customer wishes to provide their own workstation or when APS uses a VME System with servo controls incorporated at that level. It is available in EIA or NEMA housing and is tailored via selection of the appropriate amplifiers and power supplies. It is usually packaged in the same chassis as the SDC but without the control processors.
Micro Digital Controller (MDC)
The MDC is a custom 2 axis servo control board suitable for Military application. The DSP based processor is supported by 128 KByte Flash and 64 Kbyte RAM memories plus a serial EEPROM and operates at 400 MFLOPS. The card has 4 channels of 16 bit ADC, 4 channels of 16 bit DAC, 32 bits of Digital I/O, and 4 channels of R/D conversion. Communications with the MDC is via 2 Hi-Speed serial RS-422 and 2 Standard serial RS-232/422/485 interfaces. The MDC is designed to add an Ethernet interface daughterboard for Hi-Speed communications.
The MDC is provided as a 6" x 9" package suitable for mounting in the base of a gimbal. Small Micro Series PWM servo amplifier can also be mounted in the gimbal for a complete turnkey gimbal/control solution whereby the customer need only supply power and communication inputs. Functionality of the MDC is completed with the software including loop closures, compensation filters, mode control, gain control, BITE, and communication protocol.
The MDC is designed for operation over a -40° to +65° C temperature range and meets most MIL-STD-810 and RTCA/DO-160 environments.