China
Africa
Explore chapters and articles related to this topic
Servo Feedback Devices and Motor Sensors
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
If the selection is limited to encoders, the first decision to be made is to select either incremental or absolute encoders. As mentioned previously, an absolute encoder provides a snapshot reading of the rotating angle and speed of the motor shaft and therefore determines the absolute position. By contrast, an incremental encoder indicates the relative position and direction of movement by adding incremental pulses to a known start position. It is ideal for speed control of motors since it provides a real-time reading of the shaft position and keeps track of absolute position by counting the number of pulses per revolution (PPR). However, this position count could be lost during a power failure or system shutdown. In such a case, it may be necessary to return the machinery to a known reference position and restart the position count before operations can resume [8.94]. For better understanding of the difference between the two types of encoders, consider the difference between a stopwatch and a clock. A stopwatch measures the relative time that elapses between its start and stop points. This is similar to an incremental encoder to measure the relative shaft position from the specified point. A clock, on the other hand, shows the exact current time within a day, similar to an absolute encoder to measure the absolute position of the shaft.
Digital Transducers
Published in Clarence W. de Silva, Sensor Systems, 2016
Incremental encoder: The output of an incremental encoder is a pulse signal, which is generated when the transducer disk rotates due to the motion that is measured. By counting the pulses or by timing the pulse width using a clock signal, both angular displacement and angular velocity can be determined. With an incremental encoder, displacement is measured with respect to some reference point. The reference point can be the home position of the moving component (say, determined by a limit switch) or a reference point on the encoder disk, as indicated by a reference pulse (index pulse) generated at that location on the disk. Furthermore, the index pulse count determines the number of full revolutions.
Permanent Magnet Brushless Motors
Published in Jacek F. Gieras, Electrical Machines, 2016
In an incremental encoder a pulse is generated for a given increment of shaft angular position which is determined by counting the encoder output pulses from a reference. The grating has a single track. In the case of power failure an incremental encoder loses position information and must be reset to known zero point.
A circumscribed local interpolation methodology for CNC machining along linear tool paths
Published in Journal of Industrial and Production Engineering, 2020
Fuyang Xu, Mansen Chen, Yuwen Sun
The experiment is finally carried out on an open platform with Panasonic MINAS-A5 servo drives and MSMD012G1 U servo motors, which are set in position control mode. The position feedback signal is obtained from the built-in incremental encoder with 2500 × 4 pulses per revolution. A detailed description of the motion trajectories is shown in Figure 14(a), the red curve represents the trajectory of the experimental path and the blue curve denotes the trajectory of the scheduled path. The actual feedrate profile for the butterfly-shaped tool path is obtained and shown in Figure 14(b), the total motion time along the actual tool path is 10.5840 s. The difference between the actual feedrate and the scheduled feedrate is very small, compared with the scheduled value in time, the actual value increased by about 1.3%. It illustrates the actual and scheduled have good agreement in the shape of the feedrate profile and the machining time. The literal record of the contour error profile is shown in Figure 14(c), the contour tolerance is acceptable for the CLI method. Compared with the point-to-point motion, the CLI method has the ability to obtain higher productivity.
3D surround local sensing system H/W for intelligent excavation robot (IES)
Published in Journal of Asian Architecture and Building Engineering, 2019
Dong-Jun Yeom, Hyun-Seok Yoo, Young-Suk Kim
Figure 11(d) illustrates the manner in which blind spots can be created by the rotary driving part of the 2D laser sensor, and in detailed design, we secured a field of view of 16.8° by increasing the length of the pipe shaft. As the surround modeling sensor is located at 4.71 m above the ground, the angle above the x-axis of the 2D laser sensor is barely scanned, and so we placed a sensor cover on top of the x-axis. The resulting scanning angle for the 2D laser sensor is 76.1° on the left and right sides. To control the rotation position (angle) of the 3D surround sensor, an EPOS 24/1 controller (Maxon) was used, and the rotation speed was designed to be controlled in four different modes (8.3 rpm, 7.5 rpm, 5.0 rpm, 3.75 rpm) As the 3D surround sensor employs an incremental encoder, an index signal must be entered to calculate the current horizontal angle of the sensor instrument. As shown in Figure 11(e), an index signal was designed to be issued when the sensor passes the – X-axis plane. The 3D surround sensor has been designed to infinitely rotate counterclockwise and scan up to 20 meters ahead until it receives a stop signal.
An Improved Torque Sharing Function to Minimize Torque Ripple and Increase Average Torque for Switched Reluctance Motor Drives
Published in Electric Power Components and Systems, 2020
The configuration of the SRM drive is given in Figure 1. The power electronic consists of 4-phase, 8/6 pole, 2HP, SR motor, an asymmetric half-bridge converter, and the DC power supply. An incremental encoder and phase current sensors are used to obtain feedback for the closed-loop control. The electronic control contains the speed controller to obtain reference torque, the torque limiter, the torque controller with the genetic-based commutation angles generator and phase position generator to obtain reference phase torque, characteristics of the machine and phase position generator to obtain reference phase current, a hysteresis band PWM to obtain switching signals.