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Distributed Motor Controller for Operation in Extreme Environments
Published in John D. Cressler, H. Alan Mantooth, Extreme Environment Electronics, 2017
A resolver is a commonly used motor position feedback mechanism within an actuator assembly. When stimulated with a sine wave, the magnetically coupled resolver returns a pair of galvanically isolated waveforms from the transformer secondary coils whose amplitudes scale as a function of the angular position of the motor’s rotor. Resolvers require no active electronic components and are resistant to extreme environments, giving way to their use within the aerospace industry. Resolvers are physically located on the rotor of the actuator. A linear variable differential transformer (LVDT) is a motor position feedback device that is similar to the resolver; however, it measures translational displacement rather than rotational displacement.
Analog Motion Sensors
Published in Clarence W. de Silva, Sensor Systems, 2016
An LVDT may be calibrated in mm/V in its linear range. In addition, a displacement offset (mm) may be provided. This typically represents the least-squares fit of a set of calibration data. Since ambient temperature and other environmental conditions will affect the LVDT output, in addition to the primary and secondary coils, a reference coil may be available for compensation of the LVDT output. Alternatively, an inductance bridge circuit, where two segments of the secondary coil form two arms of the bridge, may be employed for generating the LVDT output. Then, compensation for environmental effects (including temperature compensation) is automatically achieved as in any bridge circuit.
Robot’s Sensors and Instrumentation
Published in Jitendra R. Raol, Ajith K. Gopal, Mobile Intelligent Autonomous Systems, 2016
A parallel-plate capacitor is used as a sensor to detect displacement, force, acceleration and pressure. The inductive devices are LVDT or RVDT (linear/reluctance variable differential transformer). The advantages of LVDT are that large displacements can be measured and the device is highly linear. The disadvantages are that they have limited frequency response (due to the AC excitation frequency and mass of the moving part) and they require complex electronic signal conditioners. The main applications of the inductive devices are measurement of displacement, acceleration, liquid level and so on.
Experimental investigation of Gerber frames subjected to elastic lateral torsional buckling
Published in Australian Journal of Mechanical Engineering, 2022
Amit S. Chaudhary, K. B. Waghulde
Figure 7 illustrates arrangement of loading; a vertical point load is set on the top flange at the mid centre of beam length. The arrangement consists of An actuator is set below the load which is applied at the mid centre of the beam length, it consists cylinder with stroke distance 150 mm and collapsed height 250 mm and the capacity is 100 KN. By controlling the rate of fluid flow, the stroke is controlled.Linear variable differential transformer (LVDT) is used in experimentation of Gerber beam for the purpose of lateral displacement measure, to measure the rotational movement clinometers are used, and load cells are used to measure the load applied by actuator.An automatic data acquisition computerised system was arranged to collect data related to lateral displacement.
Microstructural analysis of the effects of compaction on fatigue properties of asphalt mixtures
Published in International Journal of Pavement Engineering, 2022
Tianshuai Li, Pengfei Liu, Cong Du, Marc Schnittcher, Jing Hu, Dawei Wang, Markus Oeser
A Universal Testing Machine UTM-250 equipped with a temperature control chamber was utilised for the indirect tensile fatigue test according to DIN EN 12697-26, as shown in Figure 4(a). The relative low-temperature value was chosen in accordance with the previous researches. Before the test, the specimens were stored at a constant temperature of 10°C for 6 h. In this study, a sinusoid loading was applied on the specimen until failure. The frequency of the repeated compressive load is 10 Hz and in a stress-controlled mode was chosen in the test. The range of the loading amplitude was between 0.035 and 0.5 MPa to ensure the peak value of the horizontal strain was between 0.05‰ and 0.3‰. Furthermore, the test time was set to 2 h in order to ensure that the same loading cycles were applied to each test specimen, and hence the fatigue damage of different internal structures can be compared. As can be seen from Figure 4(b), the loading device consists of two loading strips fixing the specimen in the vertical direction. For the measurement of the horizontal deformation, two Linear Variable Differential Transformer (LVDT) are used. They are positioned opposite to each other and secured onto the mounting frame with screws. The mounting frame itself is attached to the specimen with securing clamps. The range of one LVDT is 0.12 mm with an accuracy of 25 × 10−5 mm.
A novel adaptive balance-drive mechanism for industrial robots using a series elastic actuator
Published in International Journal of Computer Integrated Manufacturing, 2020
Huashan Feng, Yaping Xu, Dewang Mao
The spring deformation value and screw compensation curve are shown in Figure 8. The spring is compressed, i.e. the LVDT output is a gradually decreasing negative value curve. The output of motor drive screw is a gradually increasing positive value curve. These measurement results indicate that the motor-screw transmission device can balance and compensate the payload variation. The compensation error was within ±0.3 mm. There are three main reasons for this error. (1) A small change in the load-end lever arm length induced by its thickness after application of different counterweight blocks. The ratio of arm length variation to bar length was about 1%. (2) Errors caused by the precision and linearity of the LVDT sensor. The precision depends on the cost of the equipment used in the experiments: a higher precision can be obtained using more expensive equipment. In this study, the precision of the LVDT sensor was 0.5%. (3) During the whole compensation procedure, the spring deformation value was nonlinear.