EE444 Embedded Systems Design - Student Projects: Marni

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DIGITAL HEIGHT MEASURING INSTRUMENT

Srikanth Marni

An engineering instrument has been designed that can be used to determine height. Degrees or Distance can also be obtained.

It is less expensive and medium size and less weight. It can measure height upto 350 feet or 4,200 inches. It mainly consists of two sensors (accelerometer sensor and ultrasonic sensor) connected to the microprocessor. The microprocessor has inbuilt LCD display. Laser diode is used for pointing positions on the object.

When used accurately, the instrument has an accuracy of better than +/- 0.7 inch for an 20 inches object.

How to measure?

It is very simple to operate it. The user has to press the button for five times to get the calculated height. The laser diode is used for pointing the device to top and base of the object. While measuring make sure that the back end of the device should be in stable position. The idea beyond this instrument can be understand from the below figure.

Figure 1

Consider the instrument is placed at the 'P' point.

Height of the object = AX * [TanA- TanB]

The height can be measured by following the sequence of steps:

Step 1: Turn the device ON and press the button (switch 1) for first time to make sure the Microprocessor is ready.

Step 2: Press the button for the second time and hold for few seconds( 3 or 4 sec). The user have to make sure that the device is almost perpendicular to the object and he has to swing the instrument slightly up and down across the horizon. This will help the instrument to take the exact perpendicular distance between the object and instrument. After releasing the button the adjacent height is displayed on the LCD display panel.

Step3: Press the button for second time and point the laser beam at the base of the object. At least hold the button pressed for 4 sec. At release of the button the angle is displaced on the LCD display panel.

Step4: Press the button for third time and point the laser beam at the top of the object. At least hold the button pressed for 4 sec. At release of the button the angle is displaced on the LCD display panel.

Step5: When the button is pressed for fifth time the calculated height is displayed.

There is also a second button (switch 2), this is used to take the mean of the heights measured of an object. Every time you measure the height press the button 2 to get the mean.

Additional Photos