Views
4 years ago

Download

Download

w P r D + _ I y P x

w P r D + _ I y P x Sensor 7 – ELECTRONICS Figure 7.1: Functional schematic of the control electronics. The operational amplifier compares w with the feedback variable r. Directly implemented in the OPAMP circuit are the P-, I- and D-contributions indicated with dashes rectangles. A second P-contribution is implemented in the bridge amplifier, which consists of two power amplifiers. The position of the MSTS DM, replaced by the coil symbol, will be contactless measured with the sensor and returned as feedback signal to the comparator. electronics, because a push pull OPAMP circuit cannot reach this minimum driving voltage. 7.1.2 Controller When considering the measured step response of the MSTS DM (fig. 6.5), it is rea- sonable to define PT2 behaviour for the control path. For the DM, a classical PID controller based on an operational amplifier as shown in [7] was applied. Since no sen- sor was definitly selected for the position feedback, the controller had to be designed for fulfilling all wiring possibilities of the P-, I- and D-contributions. Figure 7.1 shows the functional schematic of the realized control electronics. This figure is leaned on the standard closed loop system (fig. 4.9). An operational amplifier compares w with x, which is conditioned with an additional circuit. The control contributions are directly implemented in the OPAMP circuit indicated with dashed rectangles. In the circuit diagram (appendix C), the feedback signal conditioning circuit consists of three additional OPAMPs to compensate the offset, adjust the gain and invert the signal if needed. This circuit diagram shows the breadboard electronics design, which offers a large range for adaption. 54

7.1.3 Sensor 7 – ELECTRONICS The laser triangulator optoNCDT 1700 from MICRO-EPSILON 2 was applied as position measuring sensor for the static and dynamic measurements. Furthermore, it was used as feedback sensor for the control electronics breadboard, whereas the conditioning circuit was adjusted to compensate the sensor’s output signal range of 0 . . . 10 V. It must be mentioned that the optoNCDT 1700 causes a dead time of 1.2 . . . 1.6 ms due to the internal analog-to-digital conversion. However, this seems to be useful at the first glance and will be discussed in the following section. A sensor for the position feedback must be found which is • small, • lightweight, • shows a linear input to output characteristic, • operates with a maximum supply voltage of +3.4 V and • causes virtually no dead time. Different sensor systems were evaluated e.g. inductive, capacitive, optical and Hall effect sensors. Thereby, the latter turned out as most promising because of the already existing moving magnet in the MSTS VCA, which can directly stimulate the sensor. An applicable space qualified sensor was not found up to the day of submission of this thesis, but is to be determined for the further project phase. 7.2 Control Results For closing the design and construction part within this thesis, the first achieved results of the controlled MSTS DM presented in figure 7.2 will be discussed. When focussing on the lower curve in the right part of this figure, it becomes clear, that the switching mode requirement can be satisfied with the controlled MSTS DM. The open/close time can be measured to < 5 ms and is therefore shorter than the value listed in table 2.1. In the right part of figure 7.2, a switching period of ≈ 100 ms is identifiable. Note the almost entirely suppression of the decaying oscillations, which otherwise occur in the 2 http://www.me-us.com/laser-sensor/ accessed on July 5, 2008. 55

English manual ? free download
English manual ? free download
Download Detailed Spec Sheet - Boydco.com
Download the theoretical problems.
English manual ? free download
Download 2008 Raptor Speakers Brochure
Download PDF - AquaFeed.com
Click here to download the abstract booklet in pdf format - MT19 - Infn
Download this presentation - Adobe PDF
English manual ? free download
Download the MC Anna Brochure here - Ortofon
Download Session 3 - Interface Tech Blog
Download program - Society For Rock Mechanics & Engineering ...
Helmholtz Coil Systems - Power Guide Marketing
Download Product Brochure
Download catalog - Saint-Tech
Download the MC Anna Brochure here - Ortofon