Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
LINIAR AND ANGULAR MEASUREMENT ACCORDING TO THE INCREMENTAL PHOTOELECTRIC PRINCIPLE WITH APPLICATIONS ON MONITORING AND CONTROL THE PRODUCTION PROCESS
Daniela Cioboata1, Paul Ancuta1, Aurel Abalaru1, Nicolae Mocanu1,Cristian Logofatu1
1National Institute of Research and Development for Mecatronics and Measurement Technique
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
Abstract – The study refers to improving the precision of the industrial processes by developing some informative systems based on micro processors integration in the control electromechanical structures of the linear and angular dimensions. The study presents a flexible acquisition, processing and data display system for increasing the precision and extension of the linear and angular measurement domain based on incremental principles, for industrial control equipments. Are presented two applications of this system for dimensional control in the automotive industry.
Key words – flexible acquisition, processing and data display system, linear and angular dimensions.
- Introduction
The dimensional measurement technique at the world wide level is constantly improving, mainly because of the explosive development of micro electronic and automatic, of the measurement techniques in coordinates and of analyze the geometrical shape assisted by computer.
Micro electronic development allowed the electromechanical integration and microprocessors integration in the electromechanical structures provided the apparition of the intelligent equipments.
Incremental numeric measurement of the angular and lineardimensions is based on using transducers and processing the measurement information by electrical signals and has its origin in the automate adjustment and control system of the processes.
Incremental tools for dimensional measurement are tools for obtaining, sending, processing and/or stocking certain information for length measurement, where measurement is made by the incremental method.
Incremental measurement is a relative measurement. Thus, it may be achieved an “absolute incremental measurement” by adding at the used tool an additional channel providing a reference signal (of zero). As a principle the incremental method presents the risk of error measurement accumulation, the risk increases if the controlled number of increments is bigger. In addition, stopping the supply damages provides the loose of the position information.
Post process, ultra precise micro measurements systems, provide the post process measurement for testing the quality of the processed material and usually this kind of measurement refers to dimensional measurement (diameter, length, rugosity, part shape, etc.).
Micro systems for measurement may use a digital processing imposing some advantages such as not sensible at vibrations and at the capacity of filtering the signal for reducing the lavatory errors, the capacity of compensating the systematic errors.
Processing the information and sending it in order to appreciate the positioning status, means ante processing, counting end evaluation of the necessary information for achieving a satisfactory control, depending on the sensor selection.
Because of the robustness, simple design, low price, high resolution (up to 36.000 imp/rotation and even more over 80.000 imp/rotation) rotation incremental transducers are more and more used for industrial dimensional measurements.
INCDMF – Bucharest has realized an acquisition, processing and data display system for modernizing certain measurement and dimensional control equipments (length and angles) and for monitoring the industrial processes based on the photoelectric incremental principle (figure 1).
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
a. b.
Fig. 1. Electronic bloc coupled with linear incremental transducer (a) and with rotation incremental transducer (b)
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
- General description of the electronic equipment
The equipment is realized using the ATMEGA 128 microcontroller, conditioning signal circuits, I2C modules, RS232 interface circuits. Data are locally displayed on a LCD type display 2 x 16 figures. The The equipments may communicate on the RS232 serial interface with a master system to whom it sends data or from whom may receive orders.
By pressing the S key the keyboard function is extended, key S is behaving as Alt key from a PC type keyboard.
The bloc scheme of the equipment is shown in figure 2.
According to the transducer type connected to the equipment, there are three kinds of proceeding, implementation by software: two for linear inductive transducers and one for rotation inductive transducer (figure 3).
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
Fig.2. Block Schema
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
The equipment has two working modalities: “LEARNING” and “ACTIONING”.
The role of the “LEARNING” module is to show for each type of operation the initial value towards which is made the measurement and in the case of the angular quota, means to define the correspondence between 1 impulse and the number of the associated seconds.
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
Fig.3. Ways of operation
Initial value may be setted like in the following table.
No. Menu / Type of measurement / Min. initial value / Max. initial value / Min. Incrementangular value / Max. increment angular value1 / Liniar,
1 impulse=1 mychron / -9999.999 / +9999.999 / ------/ ------
2 / Liniar,
1 impulse =0.1 mychron / -999.9999 / +999.9999 / ------/ ------
3 / Angular,
1 impulse=xx.xxx seconds / -359g59m59s / +359g59m59s / 0.001 / 99.999
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
The effect of operating the keys in LEARNING module
The switch between the setting screens is made by the S9 combination of keys.
The introduced values become effective by pressing key M when switching between menus or when passing into OPERATION module.
The initial value may be set again by acting key R.
Another role of the key R is to initiate the angular increment with 64.8 “/ 1 impulse value.
Within mode 3, switching between lines in order to set the initial angular value or angular increment, is made by the combination of keys S7.
The end of introducing the number values by keys is made by acting the key M. Acting key U is changing the sign of introduced number value.
The combination of keys S1 switches the equipment way of operation.
In OPERATION working module the equipment is continuously reading the number of the arrived impulses form the transducer and displays this number, having as an off set the initial value.
The point displayed on the screen means the decimal point.
Ex: Vini=100.000 mm andfrom the transducer arrived 10.000 positive impulses. Displayed quota will be 110.000 mm
(100000+10.000=110000).
Admitted keys in OPERATION module
Acting key R re sets the value of the current quota, obtaining QUOTA= Vini
Acting key M sends the displayed quota on the serial interface to PC or another connected device.
The message is clearly including the type of the measurement, the measured value, the initial value, a CRC code for verifying the message correctness and the couple of characters CR LF.
Technical basic characteristics:
- Display capacity:
- for linear incremental transducer with the resolution of 0,001 mm: 999.999
- for linear incremental transducer with the resolution of 0,0001 mm: 99.999
- for rotation incremental transducer with the resolution of 999.59.59
- Resolution:
- linear incremental transducer: 0,001 mm; 0,0001 mm
- rotation incremental transducer: pre set according to the transducer resolution ( including 64.8”)
- serial out coming for displayed data: RS 232
- programming menu of the used transducer
- pre set menu of the display resolution for rotation incremental transducers
- pre set menu of the reference values
- display of the reference values
- supply tension: 220 V/50 Hz
- functioning temperature: 0…+40 C
- consumed power: max.5VA;
- dimensions: max. 245 x 65 x 200 mm
Applications
We present 2 applications of the system for dimensional control in auto incursion.
- Part type axle with came control device– linear quota measurement
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34
Liniar and angular measurement according to the incremental photoelectric principle with applications on monitoring and control the production process
/ 1. positioning microscope2. displacement guidelines
3. incremental line
4. cursor incremental line
5. measurement slide
6. indexer
7. indexer line
8. stop cover
9. part for measurement
10.focusing rosette
11.fix edge
12.mobile edge
13.lever acting the mobile edge
14. fine advance
15. end course/run damp
16.electronic bloc
Fig.4 Device for controlling the part type axle with came – linear quota measurement
- Device for controlling the part type axle with came – angular quota measurement
/ 1. body/frame
2. prisms
3. damp
4. fix edge
5. mobile disk
6. rotation incremental disc
7. caliber of “ZERO” quota
8. lever for acting the mobile edge
9. mobile edge
- elastic pin
- electronic bloc
- acting lever transversal displacement
- proximity sensor
- transversal slide
- precision linear guiding
- imitate
- prism for orientation
- caliber support
- lever profiled for measuring the angular position
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The Romanian Review Precision Mechanics, Optics & Mecatronics, 2008 (18), No. 34