Sean Cleary - Sensor Testing

 Introduction

The small swarm robots that we are working it with are equipped with two Sharp 2Y0A02 sensors, which use infrared diodes in order to detect distance. This week these sensors will be tested in order to see how they operate.

To start information on the sensors can be gained through looking through the datasheet available.

Figure 1: Chart of output voltage compared to distance. 

The chart comparing the output voltage compared to distance can be seen above. This will be compared to the actual results to see if it matches up.

Process

In this experiment the sensor will be connected to both a PIC board (to provide power) and an oscilloscope (to view the analog output). The oscilloscope will be configured in DC mode, initially the oscilloscope was configured in AC, which resulted in the results being incorrect. Once this was caught, it was rectified, allowing for the correct results to be displayed.

In order to properly test the sensor, a large sheet of cardboard was held at a variety of distances from the sensor. This tested the voltage output which could be compared to the graph in figure one.

Figure 2: The voltage response when the cardboard is at 15cm 

Figure 2 shows the first test, in which the cardboard is at a distance of fifteen centimeters. As can be seen in figure 1, this should result in a voltage of nearing three volts. The results from this test confirms this, with the oscilloscope showing a voltage of 2.98v.

Figure 3: The voltage response when the carboard is at 30cm

Figure three shows the result when the cardboard is 30cm away. Here the graph shows that the voltage should be around two volts. The actual result shows that it is just under two volts, being 1.86 volts overall.

Figure 4: The voltage response when the cardboard is at 50cm

Figure four shows the result when the cardboard is 50cm away. There is a drop off between here and figure three, however this drop off is not as sharp as the drop off between figure two and figure three. Here the voltage has gone from 1.86v at 30cm, to 1.42v at 50cm. The result at fifty centimetres is in line with the graph above, as the graph reports that the result should be just under 1.5v.