Servomotor drive

In high-temperature cells, special valve designs are required to handle the fuel gas, which is up to 1000°C. These valves are used to balance the gas flows between stacks and for stack isolation to permit continued operation when some of the stacks fail. High-temperature servomotor drives (Mitsubishi and Hitachi) can be used on these valves. 

In 2007, MIT professor Hugh Herr demonstrated the first powered ankle prosthetic device [8], Mechanical compliance is one key to the proper operation of an ankle prosthetic since the foot is constantly interacting with surfaces of varying compliance. The MIT ankle does not use EPAM but rather uses a linear servomotor drive (rotary motor plus a lead screw) in combination with a spring in order to achieve a controllable compliance. A similar ankle orthotic device has also been developed [9]. Replacing this relatively heavy, bulky and noisy mechanism with an EPAM actuator would be desirable. 

Fig. 6.14 Left. Sketch of the HiDrip droplet generator nozzle head (a) servomotor drive, (b) adjusting thread for sealing between (c) and (d), (c) multiple-hole cutter disc, and (d) single-hole nozzle plate. Right. Sketch of the experimental setup for binary drop collision. The colUsion velocities are varied by adjusting the angle between the two streams of drops...

Considering a widely used ball screw feed drive design, the system consists of a current amplifier, servomotor, lead screw coupling mechanism, ball screw with preloaded nut, table carrying workpiece, guide friction, and feedback sensors. Figure 1 shows the overall structure. 

Servo press with link drive system The servomotors replace the flywheel. One or more... 

The key component, as shown in Figure 1.20, has a GMA structure.The position is constantly monitored by an electrostatic gap sensor. The feedback control selectively drives the AC servomotor for a large infeed or the GMA for a fine infeed. 

An all-electric machine has no hydraulic pumps. The toggles in the clamping unit are extended and retracted by a servomotor and a reduction drive gear is used to achieve the required forces. The clamps are much more stable since they have no hydraulic system to generate heat and the servomotors provide extremely accurate movement of the machine components. It is also much cleaner to operate than the other types of molding machines. All-electric machines are the machine of choice for most medical products. 

In the absence of carbon monoxide in the sample cell, the two sensor chambers are heated equally by IR radiation from the two sources. If the sample contains carbon monoxide, however, the right-hand beam is attenuated somewhat and the corresponding sensor chamber becomes cooler with respect to its reference counterpart. As a result, the diaphragm moves to the right and the capacitance of the capacitor changes. This change in capacitance is sensed by the amplifier system. The amplifier output drives a servomotor that moves the beam attenuator into the reference beam until the two compartments are again at the same temperature. The instrument thus operates as a null balance device. 

Commercial all-terrain robots made by iRobot and ActivMedia weigh 39 to 100 kg and cany payloads of 7 to 100 kg. Powered by two DC servomotors and a 4-wheel differential-drive system, these battery-operated robots run for 2 to 6 hours at speeds between 1 and 2 m/s. With no navigation instruments or software, these robots cost from 7,000 to 22,000. They could potentially be retrofitted for solar-power operation, but they are not designed for low-temperature operation, and the solar panels alone could comprise the entire payload budget. 

Pneumatic as well as hydraulic drives are used for the movement of the needle. Recently, electromagnets and servomotors are used for this application as well (Figure 1.51). 

The subsequent use of the rectified signal depends on the photometric system employed. In single-beam systems it is fed directly to a potentiometric recorder. However, in a double-beam optical null system the rectified signal is remodulated, this time at the line frequency (e.g., 60 Hz). The object of this is to obtain an ac signal which can be amplified to sufficient power to drive a servomotor, which then positions the optical attenuator to establish a null signal. Line-frequency remod-... 

In 1960s, in order to reduce the time spending in angle calibration, H. Takasaki [11] used automation servomotor technology to drive polarizer and compensator and set the azimuth of polarizers automatically. However, in this configuration, it was still unavoidable to use human eye in the azimuth reading. Of course, the subsequent ellipsometry data processing was still involved in the human. So this type of ellipsometer was only a semi-automatic ellipsometer. 

In a motor-driven self-nuUing ellipsometer, the dc feedback currents are used to drive servomotors instead of being passed through the Faraday cell. As an alternative to the polarizer modulation described above, crystals with electro-optic effect (e.g., Pockels effect) can be used to modulate the relative phase retardation by an electric ac field. Independent modulations of polarizer... 

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