Drive control unit

Mossbauer spectra are usually recorded in transmission geometry, whereby the sample, representing the absorber, contains the stable Mossbauer isotope, i.e., it is not radioactive. A scheme of a typical spectrometer setup is depicted in Fig. 3.1. The radioactive Mossbauer source is attached to the electro-mechanical velocity transducer, or Mossbauer drive, which is moved in a controlled manner for the modulation of the emitted y-radiation by the Doppler effect. The Mossbauer drive is powered by the electronic drive control unit according to a reference voltage (Fr), provided by the digital function generator. Most Mossbauer spectrometers are operated in constant-acceleration mode, in which the drive velocity is linearly swept up and down, either in a saw-tooth or in a triangular mode. In either case. 

Fig. 3.2 Triangular velocity reference signal top) and drive error signal bottom) of a Mossbauer drive operating in constant acceleration mode. The error signal is taken from the monitor output F of the drive control unit (see Fig. 3.1). Usually it is internally amplified by a factor of 100. Here, the deviations, including hum, are at the 2%o level of the reference. The peaks at the turning points of the triangle are due to ringing of the mechanical component, induced by the sudden change in acceleration (there should be no resonance line at the extremes of the velocity range)...

Since the actual motion of the Mossbauer drive, as for any frequency transmission system, can show phase shifts relative to the reference signal, the ideal folding point (FP) of the raw data in terms of channel numbers may be displaced from the center at channel number (N — l)/2 (= 255.5 in the example seen earlier). The folding routine must take this into account. Phase shift and FP depend on the settings of the feedback loop in the drive control unit. Therefore, any change of the spectrometer velocity tuning requires the recording of a new calibration spectrum. 

Fig. 7.2.3 Block schematic of a capacitive yaw-rate sensor system 1, sensor element 2, drive control unit 3, capacitance to voltage converter 4, synchronus demodulator 5, amplifier 6, low pass filter 7, signal conditioner for the reference phase 8, control unit...

Electric power-assisted steering systems are more and more replacing hydraulic systems. To improve fuel economy, the power assistance is provided by an electric drive. Such a system only consumes energy when power is supplied, unlike hydraulic systems. A torque sensor in the steering column provides the input signal to the drive control unit. An example of an electric power steering system is shown in Fig. 7.12.4. 

Trajectory generation algorithm sends discrete time-stamped position commands to individual feed drive control units as shown in Fig. 4. The first (dxrldt), second (d Xrldt ), and third d Xr/ d ) derivatives of the discrete position... 

The cost of an electric-drive rotaiy-cutter sample of the smallest size manufactured—suitable for gravity sampling of fine particulate solids or shiny flow—including timer and control unit was approximately 5,000 in 1996. 

This paper describes work on equipment and instrumentation aimed at a computer-assisted lab-scale resin prep, facility. The approach has been to focus on hardware modules which could be developed and used incrementally on route to system integration. Thus, a primary split of process parameters was made into heat transfer and temperature control, and mass transfer and agitation. In the first of these the paper reports work on a range of temperature measurement, indicators and control units. On the mass transfer side most attention has been on liquid delivery systems with a little work on stirrer drives. Following a general analysis of different pump types the paper describes a programmable micro-computer multi-pump unit and gives results of its use. 

Fig. 3.17 Leftlbottom Picture of the drive (cylindrical piece length 40 nun diameter 22 nun) and its control unit (quadratic box holding the cylindrical drive unit) this whole unit slides into the detector system unit (top part in the left picture) Right Transfer function of MIMOS II velocity transducer (see also Sect. 3.1.1). For details of the drive unit and the model describing its behavior see [36, 45]...

However, motor speed was also the first function in washing machines to be electronically controlled. The standard nowadays are controllable AC- or DC-mo-tors. Depending on the textile type or wash program, such drives can be used to achieve optimal wash speeds, reversing rhythms and activation times. Usually a tachogenerator on the motor is used as a speed sensor. Such a smaller modem motor, connected to a small electronic control unit, is shown on the right hand side of Fig. 3.2. 

Throttling of the suction of centrifugal and axial compressors wastes less power than throttling the discharge. Even less power is wasted by adjustment of built-in inlet guide vanes with a servomechanism which is a feedback control system in which the controlled variable is mechanical position. Speed control is a particularly effective control mode, applicable to large units that can utilize turbine or internal combustion drives control is by throttling of the supply of motive fluids, steam or fuel. 

Fluid-filled bulbs deliver enough power to drive controller mechanisms and even directly actuate control valves. These devices are characterized by large thermal capacity, which sometimes leads to slow response, particularly when they are enclosed in a thermal well for process measurements. Filled-system thermometers are used extensively in industrial processes for a number of reasons. The simplicity of these devices allows rugged construction, minimizing the possibility of failure with a low level of maintenance, and inexpensive overall design of control equipment. In case of system failure, the entire unit must be replaced or repaired. 

Similar to computer technologies, so-called plug and play micro fluidic devices were developed. These devices are composed of a fluid driving unit and a polymer chip containing micro fluidic channels and reservoirs. The one and only connection is an electrical bus system which connects the chip with the external control unit. By filling the reservoirs with reagents, the chip can be used for performing chemical reactions or biochemical analysis [72],... 

Separation capillary columns are made in fluorinated ethylene- propylene copolymer. Detection is achieved by conductivity cells and an ac. conductivity mode of detection is used for making the separations visible. The driving current is supphed by a unit enabling independent currents to be preselected for the preseparation and final analytical stages. The run of the analyser is controlled by a programmable timing and control unit. The zone lengths from the conductivity detector, evaluated electronically, can be printed on a line printer. 

Compaction simulators (Fig. 20) were designed to mimic the compression cycle of any prescribed shape by using hydraulic control mechanisms that are driving a set of two punches (upper and lower) in and out of the die. All hydraulic compaction simulators are similar in design and construction. A compaction simulator consists of several main units the load frame (column supports and crossheads with punches), the hydraulic unit (pumps and actuators that move the crossheads), and the control unit (electronic console and computer). Usually, a simulator accepts F tooling only, but can be retrofitted to use standard IPX B tooling. Under computer control, the hydraulic actuators maintain load, position, and strain associated with each punch. 

In addition to lubricating the engines, turbine lubricants are also required to lubricate a number of associated systems such as auxiliary power units and constant speed drive units and to act as hydraulic fluids, for instance, in the propeller pitch control units of some turbo-props. 

The amplifier (5) boosts the signal, eliminates temperature coefficients, and adjusts the offset. The low pass filter (6) limits the bandwidth. The drive circuit is a closed loop system to achieve a stable drive oscillation. It consists of a structure (not drawn) that detects the oscillation movement of the drive of the yaw-rate sensor element, a control unit (2), and an actuator (not drawn). The start circuit (9) initiates the drive oscillation at power on. The block (8) generates all necessary adjustment signals and includes the logic circuit for the trim and an EPROM (erasable programmable read-only memory) for the storage of the trim data. 

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