Motion Control Systems Information
Integrated motion control systems contain matched components such as controllers, motor drives, motors, encoders, user interfaces and software. The manufacturer optimally matches components in these systems. They are frequently customized for specific applications. Number of axes, motor power and torque, controller interface and networking options are developed with the applications area of a manufacturer. Systems specifications, network options, direct backplane interface, and environment are all important to consider when searching for motion control systems.
Important system specifications to consider when selecting motion control systems include included components, integral encoders, integral resolvers, integrated power supply, motor or drive type, number of axes, power output, torque capacity, rated speed, sampling frequency, analog-to-digital resolution, and communication interface. Components included in motion control systems include controller-drive-motor, controller-drive, and drive-motor. Encoders provide digital position feedback in closed-loop systems. Usually attached directly to the motor. Resolvers provide analog position feedback in closed-loop systems. Usually attached directly to the motor. A power supply provides appropriate voltage for motor drive(s). May be matched to controller and motor, or integrally attached. Motor or drive type choices include AC, DC, or stepper. The number of axes can be 1, 1 ½, 2, 2 ½, 3, 3-8, and more than 8. Power output is the power capacity of the motor. Rated speed typically refers to no-load allowable continuous speed rather than short-term peak speed. This is dependent on the motor specifications. Sampling frequency should be at least twice the input signal's highest frequency component. (Nyquist Theorem). It is the rate at which the control system monitors feedback (encoder, resolver) in order to provide correction commands. Analog-to-digital resolution is the size in bits of A/D converter. A larger number of bits increases the resolution of the digital signal. Choices for communication interface include hand-held or portable interface, computer interface, serial interface, parallel interface, and integrated software.
Network options for motion control systems include networkable system; this specification is for a motion control system that is designed to be a node of a communications or motion control network. Both monitoring and command functions may be part of the overall network. There are several networks designed to provide connectivity between machines, PCs, and PLCs. They each use a specific protocol that handles data transfer, handshaking, network node polling, time-critical control commands, etc. Networks used for motion control and feedback are often specialized; contact motion control manufacturer to ensure compatibility. Choices include ARCnet, AS-I, Beckoff I/O, CANbus, DeviceNet, Ethernet, Foundation Fieldbus, IEEE-1394 (Firewire®), IEEE P1451, Interbus-S, Profibus, SDS (Smart distributed system), Sensoplex, SERCOS, and Seriplex . A direct backplane interface is for motion control systems that includes a PC card that plugs directly into the backplane or bus of the PC. Interface options include ISA / EISA (PC-XT/AT), MAC PCI (Nubus), Multibus I or II, PC/104, PCI bus, PCMCIA (PC Card), STD Bus, SUN SPARCstation, S-bus, VME Bus, and VXI / MXI Bus. An important environmental parameter to consider when searching for motion control systems is the operating temperature.