GoPiGo distence sensor

[William Ray Wing]

> On Jun 15, 2016, at 10:59 AM, Joel Goldstick <joel.goldstick at gmail.com> wrote:
> 
> On Wed, Jun 15, 2016 at 10:15 AM,  <ldompeling at casema.nl> wrote:
>> I have a small robot on wheels named the GoPiGo.
>> What I want is if the distence sensor read the same distence for let say 5 seconds then the GoPiGo go's backward.
>> 

When I look at the API, I see two functions related to distance traveled.  An encoder target function that presumably reads the numbers from an angular encoder on the drive shaft and allows you to specify a number for the encoder to seek, and a “us_dist” function that seems to read the proximity to an object from an ultrasonic sensor.  I’m going to assume you are referring to the numbers from this ultrasonic distance sensor.  So, I think what you are saying is that if the numbers from the distance sensor are unchanged for 5 seconds (as would be the case if the GoPiGo were being blocked by something) then you want it to back up. 

As MRAB has commented, what you need to do is set up a delay loop that wakes up every second (or more frequently if you want more time resolution) and reads the number returned by the us_dist function.  Compare it to the previous reading and if unchanged increment a counter.  If it has changed, the robot has moved so clear the counter.  If the counter reaches your five second trigger point, call a go_back function you write.

-Bill


>> But I don't now how to program this in python.
>> The Api functions for the GoPiGo are here: http://www.dexterindustries.com/GoPiGo/programming/python-programming-for-the-raspberry-pi-gopigo/
>> 
>> Can someone help me with this.
>> 
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> Joel Goldstick
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