UltraSonic

Comparison of NXT and EV3 UltraSonic Sensors

Today I'll examine these two sensors to see if there is any difference. I suspect that they will perform the same, but my overall goal is to examine alle aspects of all sensors of the EV3. Since I've worked with the NXT Sensors before, I'm using them as a benchmark for how well the newer EV3 sensors perform.

Test inspiration

The next couple of blogposts will be related to this other blog I helped create. The ultrasonic sensors where tested duing week3 of the above experimentations. When I refer to weeknumbers hereafter, I'm referencing to this afformentioned blog.

Week3 was a week dedicated to understanding how ultrasonic sensors work. My goal with the below experiment is not to recreate the expeiment exactly as was, but rather to test if the experiment is feasible with the new EV3 using leJOS. While I'm doing this, I'm sure some sort of picture of how well the new hardware performs will emerge.

The experiment

My test-setup is as depicted below:

Setup for the distance test

The plastic top of the LEGO-box was selected, as we found (in our privious tests), that measuring the distance to some non-vertical thin plastic object posed a significant challenge to the NXT ultrasonic sensor.

Ultrasonic Distance Measurements
Actual distance*	NXT	EV3
45	48	0,475
80	87	0,834
97	108	1,115
110	inf	1,206
120	inf	1,315
137	inf	1,499
>137	inf	inf

* based upon eyemeasure of where the sensor is relative to the measuring tape

I tried my best to make sure that all measurements where at exactly the same distance and I feel confident that they where all done within 1cm of actual distance (to the bottom of the angled slope of the plastic).

First off I suspected that the problem with the big difference of accuracy was because my NXT sensor was damaged/used, so I tried another one, with the same results. This leads me to conclude, that the new EV3 Ultrasonic sensor is actually quite a bit better at detecting difficult objects.

Second test

I did implement the WallFollower mentioned on the other blog, but the result was just as bad as in our first attempt (I used the exact same code, corrected for the new sensor-framework). These results are not included, but I wanted to confirm that it is indeed possible to make a wallfollower (my implementation was kind of deranged, but it kind of followed a wall).