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Date: 2015-10-07; view: 524.

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A typical open-loop … control system includes … with a programmable indexer or … and motor driver. This system does not need feed­back sensors because load position and velocity are controlled by the predetermined number and direction of input digital pulses sent to the motor driver from the controller. Because load posi­tion is not continuously sampled by a feedback … (as in a closed-loop servosystem), load positioning accuracy is lower and position errors (commonly called step errors) accumulate over time. For these reasons open-loop systems are most often speci­fied in applications where the load remains …, load motion is simple, and low positioning speed is acceptable.

There are five different kinds of motion control: point-to-point, sequencing, speed, …, and incremental. In point-to-point motion control the load is moved between sequences of numerically defined positions where it is stopped before it is moved to the next position. This is done at a constant speed, with both velocity and distance moni­tored by the motion controller.

Point-to-point positioning can be performed in single-… or multi-axis systems with servo­motors in closed loops or stepping motors in … loops. X- Y tables and milling machines position their loads by multi-axis point-to-point control. Sequencing control is the control of such functions as open­ing and … valves in a preset sequence or starting and stopping a conveyor … at specified stations in a specific order. Speed control is the control of the velocity of the motor or actuator in a … . Torque control is the control of motor or actuator current so that torque remains constant despite load changes. Incremental motion control is the simultaneous control of two or more … such as load location, motor speed, or torque.