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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
servo drive an automatic control system in which position, speed, or torque are the control variables. servomechanism a closed-loop control system consisting of a motor driven by a signal that is a function of the difference between commanded position and/or rate and measured actual position and/or rate to achieve the conformance. Usually a servomechanism contains power amplification and at least one integrating element in the forward circuit. session an instance of one or more protocols that provides the logical endpoints through which data can be transferred. set associative cache a cache in which line or block from main memory can only be placed in a restricted set of places in the cache. A set is a group of two or more blocks in the cache. A block is first mapped onto a set (direct mapping defined by some bits of the address), and then the block can be placed anywhere within the set (fully
Fundamentals of Digital Motion Control
Published in Richard L. Shell, Ernest L. Hall, Handbook of Industrial Automation, 2000
Ernest L. Hall, Krishnamohan Kola, Ming Cao
A servo system is a motor control system that combines various components to automatically control a machine’s operation. It is generally composed of a servo drive, a motor, and feedback device. The controller gets a feedback signal and outside control signal and controls the servo drive and motor together to precisely control torque, velocity, or position of the motor shaft. The feedback continuously reports the real-time status, which is compared to the command value. Differences between the command position and feedback signals are automatically adjusted by the closed-loop servo system. This closed loop provides the servo system with accurate, high-performance control of a machine.
Servo Feedback Devices and Motor Sensors
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
The test setup of velocity ripple measurement is shown in Figure 8.25. To enhance the smoothness of motor operation, an inertia wheel is mounted at the end of the motor shaft. The operation of the motor is controlled by a servo drive.
Stability analysis for nonlinear closed loop system structure
Published in Systems Science & Control Engineering, 2020
Wang Jianhong, Ricardo A. Ramirez-Mendoza
To extend the above nonlinear closed loop system structure in Figure 1 to one general case, we consider one much more complicated system from engineering practice in Figure 2, which is the block diagram of a typical control system for an aeroplane rotating about a single axis. The inner loop is the so-called control surface position feedback or follow-up. In Figure 2, air frame is the plant , is the input variable for the whole closed loop system and is the input variable for the plant . The feed-forward controller includes some modules, such as an amplifier, a compensating network power stage, a servo drive and a control surface. Two feedback controllers exist in this more complicated system. The feedback controller in the inner loop is a proportional controller, and the other feedback controller in the outer loop is , which includes two modules, i.e. compensating network and amplifier. The simplified structure of Figure 2 is shown in Figure 3, which is our considered closed loop system structure in this section.
Adopting Robotic Systems to Enhance Vibration Control of Footbridges
Published in Structural Engineering International, 2018
Kevin Goorts, Sriram Narasimhan
To assess the position tracking performance, the reference case under no base excitation is first considered (Fig. 9). The EMD position was measured using a linear magnetic encoder built into the motor and accessed through feedback to the servo drive. Under no base excitation the servo controller accurately followed the desired position trajectory with a measured time delay of 17 ms. The first sign of disturbances in the position tracking occurred when the peak base excitation exceeded 1.75 m/s2. These small disruptions only occurred when the EMD reached frequencies beyond 4 Hz, which is also evident in Fig. 6. As the peak base acceleration increases, the magnitude of the disruptions increases and disturbances are observed at lower EMD frequencies. The disturbances caused under 3 Hz harmonic base motion at an amplitude of 10 mm (yielding a peak acceleration of 3.6 m/s2) are presented in Fig. 10, which shows that the position tracking at this point begins to experience small oscillations as the servo controller works to reject the external disturbances. The final test, which reached a peak base acceleration of 4.9 m/s2, could not be completed due to controller instability. Under this magnitude of base excitation, the EMD controller was unable to follow the position trajectory beyond 2 Hz.
Field-programmable analogue arrays for the sensorless control of DC motors
Published in International Journal of Electronics, 2018
J. Rivera, I. Dueñas, S. Ortega, J. L. Del Valle
The experimental set-up consists of a 90 DCV power supply feeding an analogue servo drive (model 20A20 from Advanced Motion Controls), which incorporates a pulse width modulator. For the hybrid implementation, the control algorithm is programmed in AnadigmDesigner2 and implemented in an FPAA, as noted in Section 3. The DC motor embeds an encoder, whose digital signals are decoded in a digital signal processor (DSP) board (dSPACE 1104), which includes a dedicated encoder connector. The board’s library is used to decode the position from the encoder digital signals. The velocity is then calculated by taking the position change rate and filtering it with a first-order Butterworth low-pass filter with an 8 rad/s edge frequency, in order to attenuate the measurement noise. In this case, by considering the edge frequency of the low-pass filter, Shannon’s sampling theorem (Phillips & Nagle, 1995) suggests that the sampling period should be lesser than 0.392 s, hence one chooses s.