Subject:
|
Re: NXT Program: How to avoid stop-and-go? (US-Sensor in angle)
|
Newsgroups:
|
lugnet.robotics
|
Date:
|
Sun, 23 Dec 2007 01:07:37 GMT
|
Original-From:
|
bigboss97 <bigboss97.geo@yahoo=stopspam=.com>
|
Viewed:
|
5966 times
|
| |
|
|
Strangely, it slows down, i.e. it detects the further distance (less
reflection?) in the same angle.
I tried to put the US-sensor vertically. It still shows the same effect.
I also notice the closer it comes the larger angle it needs to get a
reaction. I observed...
When the vehicle hits the wall with a flat angle and I leave it running, it
keeps on pushing to the wall. I noticed that it only turns around when the
vehicle has been pushed to a position of almost 90 degree. The sensor is
almost covered by the all. The angle range is even smaller than if it comes
from a distance.
Brian Davis-3 wrote:
>
> In lugnet.robotics, bigboss97 <bigboss97.geo@yahoo.com> wrote:
>
> > Why does the sensor detects < 30cm, but misses < 20cm for flat angle?
>
> At a glancing angle (not approaching the wall "head on" at 90°, but at an
> angle)
> very little sound energy will be reflected back towards the sensor. If
> there
> isn't enough energy reflected back for the sensor to "hear" the echo, it
> won't
> detect the wall. This is complicated by the fact that the field of view of
> the
> sensor change with distance - very close to the sensor, the sensor can't
> detect
> something that is only off center by a couple of cm, but further away,
> something
> that's just 5 cm of the midline is only a small angle away from the
> midline.
>
> > Shouldn't the sensor be more reliable when the distance is smaller?
>
> In general, yes, except for the field of view issues mentioned above. In
> particular, the two "eyes" of the sensor have different purposes: one
> sends the
> sound out, while the other listens for the return. It's really the angle
> that
> those two points make with the object being detected that matters, so for
> objects at an angle to the sensor, it might be more "blind" to the left or
> right.
>
> --
> Brian Davis
>
>
--
View this message in context:
http://www.nabble.com/NXT-Program%3A-How-to-avoid-stop-and-go--tp14446433p14474869.html
Sent from the LEGO Robotics mailing list archive at Nabble.com.
|
|
Message has 1 Reply:
Message is in Reply To:
10 Messages in This Thread:
   
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
This Message and its Replies on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
