mBot 2 ultrasonic dist reading pegs to 300

#1

Just got the mbot2 two weeks ago. While playin with it, coding all kinds of things, noticing this issue:
After extended usage, the ultrasonic begins to stop reading distance properly, and starts returning 300.
Extended usage means 10 - 30mins.
I have code that is displaying the sensor reading live on the cyberpi display with each pass. I can see where the distance is reporting properly, then begins to intermittently return 300 every so often, and then a few mins later it just stays pegged at 300 and stops working - it will have no reaction to putting your hand in front of it etc. When this happens, if i stop the program, disconnect the ultrasonic cable and reconnect, it comes back to working for another extended time. But seems to come back repeatedly.

I have latest firmware 44.01.011 and using mblock v5.4.3

Any ideas?

#2

Hi there! The Ultrasonic sensor on the mbot 1 does this, too. It does this because it is using echolocation and can’t accurately pinpoint the centimeters it is reading, so it defaults to 300. Can you tell me what symptoms you notice when the robot is in front of an object? Do not move the robot.

#3

when it is operating properly:

  • mbot moves fwd at 50rpm
  • sensor reading is pegged at 300 (properly) when there isnt anything for a long distance
  • sensor starts reading objects sub300cm and decrements the dist with each pass of code. so for example, 300.0, 290.1, 280.2, 2970.3, 260.4, etc… until it achieves setpoint and stops per my code

when it starts flaking out:

  • mbot moves fwd at 50rpm
  • sensor reading is pegged at 300 (properly) when there isnt anything for a long distance
  • sensor starts reading objects sub300 and decrements the dist with each pass of code. BUT! intermittently will get incorrect reading of 300.0 so for example, 300.0, 290.1, 280.2, 297.3, 260.4, 300.0, 240.6, 230.7, 300.0, 300.0, 200.9, etc.

When it totally stopped working, it’s the above, but 300.0 300.0 300.0 on each pass even after running into the object,

In all of the above, the course is exactly the same, the object is exactly the same. We are running a course in my hallway. Once this happens, it stays this way, there is no way to bring it “back to life”. stopping code, starting over, sensor continues to read 300.0 no matter what is in front of it.

And like I said, a quick disconnect / reconnect of the connector will bring it back to life, and we can keep going for another 30 mins or so, and then it happens again.

#4

Weird… I suggest you contact Makeblock support (support@makeblock.com) about this. It should be in warranty because you bought it two weeks ago. I don’t know what else to tell you.