From Motors and Drives

Introduction
The servomotors used in industry today are used in a closed-loop servo system. To understand how the servomotor is used in the system, it is first necessary to review the entire system. Figure 3-44 indicates a block diagram of a typical servo system.

A reference input (typically called a velocity input) is sent to the servo amplifier, which controls the speed of the servomotor. Directly mounted to the machine (or to the servomotor) is a feedback device (either an encoder or resolver). This device changes mechanical motion into electrical signals and is used as a feedback loop. This feedback loop is then sent to the error detector, which compares the actual operation with that of the reference input. If there is an error, that error is fed directly to the amplifier, which makes the necessary corrections.

In many servo systems, both velocity and position are monitored. (Note: In servo systems, the word "velocity" is often used to describe speed control. Velocity indicates a rate of change of position, with respect to time. It also indicates a rate of motion in a particular direction, with respect to time.) The velocity loop control may take its command from the...


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Products & Services
Noncontact Safety Interlock Switches
Noncontact safety interlock switches couple a moveable guard door with the power source of the hazard. For noncontact actuating interlock switches, the guard door is linked to the control circuit contacts via a magnetic or electronic field.
Flap Wheels and Specialty Abrasives
Flap wheels and specialty abrasives includes cartridge rolls, cross pads, sleeves, unitized or convolute wheels, interleaved flaps, flap discs and other specialized abrasive products converted from coated or nonwoven abrasives.
Countertops
Countertops are horizontal work surfaces that are used in workrooms, kitchens, and other food preparation areas. They are often installed above and supported by cabinets.
Depth Gages
Depth gages are used to measure of the depth of holes, cavities, or other component features.
Press Brakes
Press brakes are used to bend and fold metal by pressing it into a die.

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