So, I'm using an HC-SR04 ultrasonic distance sensor for my project, and I've run into a peculiar problem. When I face the sensor straight ahead, it works wonderfully, and has a range of about 3 meters. It also works just as well when faced straight up or straight down. However, once I put it at any angle greater than or equal to 30 degrees, it suddenly begins giving bad readings and has a range of only 50 cm (when faced at a thirty degree angle, it should be reading a little more than 100 cm, but instead is reading 270). Has anybody else run into this problem before? If so, have they found a solution? Thanks in advance.
post a photo of a drawing showing dimensions of the two test scenarios. Show any walls or flat surfaces within 300 mm of the sensor in the direction it is facing. Give the shape and dimension of test object or target used for test.
I assume most of the signal is send right to the front .
check picture on this link - http://home.roboticlab.eu/en/examples/sensor/ultrasonic_distance -
it might explain behavior
Using the part at angle disperses the signal, so the returns don't make it to the receiver, and it might even get false returns from other surfaces.
Think of a pool ball hitting a bumper - straight ahead, it comes back. The bigger the angle from straight ahead, the farther it is from the starting point when it bounces off the bumper. Too far, and it is out of reach on the return trip.
Has anybody else run into this problem before?
I think about everybody has. It is one of the weaknesses of ultrasonic distance sensing.
Thanks for all of the great responses. I guess I'll just have to desl with the fact that it won't work as I intended.
What are you trying to do ? Maybe there is another way.
the main lobe on both the Tx and Rx is about 60 degrees around the centre of the "business end"
If you mount the HC-SR04 vertically you will get better results at an angle.
I had a similar project. Unfortunately I faced the same problem. I the image below you can see the readings I'got. I even mount the sensor vertically but the results were the same. The surface had a |_| shape and I have placed the sensor in the middle.
In the picture measurements were taken every 10 degrees.
