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Grup Riset: Low Cost & Automated Method and Instrumentation Analysis

Pada hari: Rabu, 24 Juli 2013 dihadiri oleh Rektor Universitas Brawijaya Prof. Dr. Yogi Sugito. Ketua peneliti Dra. Hermin Sulistyarti, PhD  telah terbentuk Grup Riset yang di danai oleh Program Hibah Keompetensi Program C Tahun 2013. Grup Riset ini adalah:

RESEARCH CENTRE OF ‘LOW COST & AUTOMATED’ METHOD AND INSTRUMENTATION ANALYSIS

Situs resmi: http://lcamia.ub.ac.id

Grup riset ini akan dibangun dalam masa 3 Tahun. Dari 19 proposal yang ada hanya 9 proposal yang layak untuk disetujui. Adapun anggota grup riset ini adalah:

Dra. Hermin Sulistyarti, Ph.D.
Bidang Kimia Analis
Dr. Atikah, MSi, Apt.
Bidang Kimia Analis
Ir. Bambang Siswoyo, MT.
Bidang Teknik Elektro
Ir. Erwin Sulistyo, MT.
Bidang Teknik Mesin
Qonitah fardiyah, S.Si., M.Si.
Bidang Kimia Analis

Anggota Grup Riset ini lintas Jurusan dilingkungan Universitas Brawijaya yaitu Jurusan Kimia, Jurusan Teknik Elektro dan Jurusan Mesin. Bidang Grup Riset ini memerlukan kompetensi gabungan sesuai dengan kajian Low Cost & Automated of Method and Instrumentation Analysis. Bidang Kimia Analisis meneliti bidang Metode Analisis Kimia, sedangkan Bidang Elektro dan Mesin meneliti bidang Instrumentasi dan Otomasinya.

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Handmade mount of helmet handycam

This time I really need to make a video documentation for the activity test fly a model airplane.  I do not want to miss important moments before the plane crashed as I have been posting here.

Since I have a bicycle helmet and a camcorder, I make my own “mount camcorders” which was originally mounted on the helmet. Mount made from sheets of aluminum with a thickness of 1.5mm. Then add slots are made from aluminum is also used to put the head of the camera tripod.

 In order to mount the aluminum can be attached firmly to the helmet, I used a rubber strap. The next head of the camera tripod can be inserted into the slot that has been made.

 As a test, a video that has been posted here, been using this helmet camcorder.

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An easy way to see the responses of ENC-03 gyro chip

Chip Gyro of ENC-03 is often used as a sensor to stabilize the aircraft or multicopter using RC. To learn seriously need to know the workings and characteristics of this chip. Data sheet for this sensor can be downloaded here. Chip is famous for its resistance to vibration and is easy to use because it has an analog output. 

The sensor works because of the angular velocity, analog output voltage will depend on the angular velocity applied to the sensor.  Sensor output voltage will follow the following equation: 

V0 is the static output voltage at angular velocity = 0 deg/s. 

From datasheet . Thus the magnitude . Sv is scale factor in mV/deg/S = 0.67V. And .

Schematic 

This circuit is the simplest. Voltage source connected to the RC tap, 100 ohms and 47uF to eliminate the ripple in the voltage source.

Gyro output voltage tap connected to the RC, 6.8KOhm and 0.68uF, serves as a simple lowpass filter to eliminate the output voltage caused by vibration. 

Vref is the output that generates a voltage as a reference that may be required by the circuit on the outside. 

At Vref is necessary to add capacitors of 4.7uF.

Microcontroller

 To read the response of the output voltage of the gyro, so easy to do I use nano Arduino board. This board contains a microcontroller type ATMega 328p. Because it already has an internal ADC, it will be easy to record responses.

In my Arduino programming using A0 as the ADC to convert the voltage output come from the gyro into digital numbers. Hereinafter ADC conversion result is sent serially to be recorded by using hyperterminal on windows.  I decided to process the data and plotted using Scilab.

Board of ENC-03 Gyro

I got this gyro board by removing the yaw gyro on kkboard. However, it should be added 100ohm resistor and 47uF capacitor on the power supply VCC. And 0.68uF capacitor also needs to be added to the gyro output.

In accordance with the data sheet, this board is placed upright and moved radially. Can also be placed upright and inverted, but the gyro output voltage changes will be reversed as well.  

To be able to move freely in the radial, required a dish to put this gyro board. To connect with pin of the Arduino board, can be soldered directly  using  cables. 

Additional compenents of resistor and capasitor can be soldered into header pins of this board. 

Dish

 In order gyro board can be moved radially with ease, need a dish to put the gyro board. The dish is made using styrofoam plate. At the center of the dish, bamboo as a holder mounted to rotate the dish. Arduino board and gyro board placed on this dish.  Furthermore, the Arduino board is connected with usb cable to the computer to record the results of Gyro responses of the radial motions.

This method is the most inexpensive and easy to make because it uses materials easily obtained is styrofoam.

Other Dish

Because I can do the job using mechanical equipment such as lathes, milling machines, drilling machines, welding machines and so forth. I prefer this dish using iron material, because it is more robust and stable during use.

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Basic Recording

The basis of recording the response of the gyro output is done by reading through the adc conversion. I am using the Arduino programming with nano board. Arduino program as follows:

void setup() {
  Serial.begin(115200);
}

void loop() {
 int sensorValue = analogRead(A0);
 Serial.println(sensorValue);
 delay(50);
}

Recording steps:

  1. Turn on Arduino by plugging USB’s arduino board to the computer.
  2. Open hyperterminal, set baud to 115200 baud, 8bit, No parity, 1 stop bit.
  3. Connect communication by clicking “Call” icon. You must ensure that the serial channel selection is correct. You will see the data receive by hyperterminal
  4. Rotate the dish, you’ll see a change of data in hyperterminal.
  5. To record and stored in a file, select the “Transfer -> Capture Text”. Then asked to fill in your name and the file folder.
  6. Turn the dish as the fourth step in accordance with your wishes.
  7. Stop record by select the “Transfer->Capture Text->Stop”.

Processing of data

The file name of the data is capture5.txt. Further data will be read and processed using Scilab program. Use the console to process manually. Scilab commands as follow:

-->// read data file into sh matrix
sh=read_csv("D:\data_scilab\capture5.txt");  

// convert sh matrix string content into d matrix as numeric
-->d=evstr(sh);

// convert adc data (0-1024, 10bit) into analog voltage
-->analog=(d/1024)*5.0;

// how big is the size of data
-->size(analog)
 ans  =

    694.    1.  

// make t matrix as time (axis plot) 0 to 693
-->t=0:693;

// plot data
-->plot2d(t,analog,style=2)

The results of the graph are shown as follows.

 

Posted in aeromodelling research, Electronics, hobby, Multicopter, RC Model, Sensor | Tagged , , | 2 Comments

Engineering design of measuring instrument for testing propeller thrust

This mechanical design serves to measure the thrust generated by the propeller.  In the world of aeromodelling, to design a model aircraft  require  the performance datas of thrusts that generated by the propeller. This will find the suitability of the propeller for the type of aircraft.

Overall, the mechanical system can be divided into several parts:

  1. Pole
    Serves to hold the thrust by the propeller. At the bottom there is a weight load that does not shake.
  2. Slider
    Is a moving part which rests two linear bearings. This section is used to hold the motor / engine and propeller.
  3. Motor/Engine and propeller mount
    Serves to hold the motor/engine and propeller. This section will vary according to the motor/engine.
  4. Load cell
    Sensors that work mechanically, driven by a slider that moves as result of thrust backward.

This mechanical system can be used to test the thrust by using electric motors or engines. Thus it will become easier to get the appropriate size of the propeller.

The data can be obtained by using a mechanical system are:

  1. Relationship between the RPM with the generation of thrust. 
  2. The relationship between RPM and current/power which is absorbed.
  3. The relationship between the current/power which is absorbed and thrust.

Point (1) The first can be used to obtain the performance of the propeller (the motor has more power), the second is used to obtain the size of the propeller in accordance with the motor / engine specific.

Point (2) can be used to calculate or test a long fly to the configuration of the motor, propeller and certain batery capacity (mAH).

Point (3) can be used to calculate the efficiency of the power absorbed by the thrust generated. 

How it works

 

The main principle of this mechanical is the Motor/Engine and propeller can move through the slider. In order to be a little friction, slider is associated in two linear bearings. The use of two linear bearings also serve for the motor does not rotate. If the wind direction toward the front, then there will be thrust to the rear. One end of the slider there is a “load cell pusher” that serves to suppress the load cell at the time when thrust generated. By adding a signal conditioner, the output voltage of load cell can be converted to digital by using the ADC.

Motor/Engine Mount

In order to hold the motor/engine include propeller need mount that can joint to slider. This mount has a variety of forms according to the motor / engine that is used.

Load Cell

To measure the thrust with a direction to the rear, I use the sensor “load cell”. 

Load cell specification is: 

  1. CAPACITY:  15kg(30lb)
  2. RATED OUTPUT:  2.0 ±0.1mv/v
  3. ZERO BALANCE : ± 0.5 % F.S.
  4. OUTPUT EFFECT ON ZERO: 0.03 %F.S. ( within 5 minutes)
  5. CREEP: 0.030~0.05 %F.S. ( within 5 minutes)
  6. NONLINEARITY ,HYSTERESIS AND REPEATABILITY: <± 0.03 % F.S.
  7. INPUT IMPEDANCE: 395±5 Ohm
  8. OUTPUT IMPEDANCE: 350±5 Ohm
  9. TEMPERATURE EFFECT ON OUTPUT %OF APPLIED LOAD: ± 0.03, %F.S./10c°
  10. TEMPERATURE EFFECT ON ZERO %OF RATED OUTPUT: ± 0.8,%F.S./10c°
  11. EXCITATION VOLTAGE: 10 Volt
  12. INSULATION RESISTANCE: 300M W
  13. PRECISION GRADE: 0.03% F.S.
  14. MATERIAL: Aluminum Alloy 2024-T351
  15. SAFT OVERLOAD:  150% F.S.
  16. STORAGE TEMPERATURE: -25 to +70 deg. C
  17. OPERATING TEMPERATURE: -10 ~ 40 deg C
  18. MAXIMUM PLATFORM SIZE: 150×200 mm
  19. CONNECTION:
    (Red: +Excitation; Black:-Excitation
    Green: +Signal; White: -Signal)
    4 leads, flexible stranded wire – length 200 mm , PVC insulated AWG 28, UL listed 
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