Practical Problems


Sensor Interferences:

Problem: Top and bottom surfaces of the housing unit contains two sensors. Sensor interference leading to inaccurate readings.

Solution: Through experimentation we determined that the minimum distance between sensors that are on the same surface must be at least 7cm apart.


Controlling Voltage:

Problem: The sensors do not give accurate values for the entire range of 2.5 - 5.5V as mentioned in the Maxbotix datasheets.

Solution: After testing with different voltages in the range of 2.5-5.5V, we observed that accurate readings occur when the power supply is 5V. We used a voltage regulator to obtain a constant 5V power supply.


Outliers:

Problem: The sensors occasionally return a random value, which is usually higher than the distance of the object in front of them.

Solution: In our design, we have used two sensors for each direction. We are considering the minimum of the two values which we obtain for each direction, so that outliers are eliminated.


Object at Angles:

Problem: The sensor cannot accurately detect objects whose surfaces make an angle greater than 45° with it, when placed at a distance of 2 feet or less. The beam reflects off the object, which leads to an error in the distance measurement. But, when the distance is greater than 2 feet, the sensor is able to detect it accurately.

Solution: We haven’t obtained a solution to this problem.


Minimum Distance Detected

Problem: The minimum distance detected by the sensors is 14.22 cm. For objects at distances less than 14.22 cm, the sensor outputs a value of 14.22 cm.

Solution: We haven’t obtained a solution to this problem.


Advice

  1. Dealing with 12 sensors can be difficult to organize. We recommend that next semester’s team color code the wires and maintain a clear and organized structure for the housing. It is also important to make sure that the wires do not get disconnected (Soldering wires is preferred). Soldering will also ensure that wires do not touch.

  2. Remember to calibrate each sensor for two seconds before taking the readings. While uploading the code into the Arduino, make that that all sensors are at least 14cm away from any object for accurate calibration.

  3. Make sure you thoroughly document all findings/ testings. Through documentation can help solve future problems.

  4. Do not rely solely on datasheet ranges/values. Sensor detection can differ based on your design. Test all claims made by the datasheet, since test conditions vary significantly.