Subject:
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Re: problems met in my project
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 28 Apr 2000 17:17:25 GMT
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Viewed:
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877 times
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In lugnet.robotics.handyboard, Lo Veng Cheong writes:
> Dear Sir,
> I am a student who is doing a mobile robot project. Since I am really
> a freshman in Robotics. So, I would like to ask you to help me to solve
> some problems met in my project. Please forgive me if my questions are
> too simple!
There are no simple questions, only simple people! Apologies to whomever
originated the quote that I just butchered. ;-)
> And now, my problem is that I have no idea on how the robot can identify
> the target objects. I do haven't any basic concept on that. Can you please
> first teach me so basic knowledge on object identification first.
Our robots do not have the rich sensory input that we enjoy. We have to
help them along quite often by making their environment understandable to
their limited sensors. This is especially so if we lack the funding of a
DARPA project! So, lets lean back and think about what our 'bots can actually
see on our budgets. We have IR sensors, heat sensors, ferrous metal
sensors and SONAR sensors that are economical for us to use.
SONAR has so many problems when used for something other than simple range
finding that we can rule them out right away. Specular reflections,
temperature boundries and even air pressure and "soft" surfaces goof them up
and will make them unreliable for object detection and recognition, especially
recognition! That leaves IR, heat and metal detectors. Lets look at the
pros and cons of these choices:
IR:
Pros
- a beacon can be installed on the objects to recognize. Each object having
a different beacon message can further differentiate them.
- Using a highly directional beacon searcher can locate an object pretty well.
Cons
- There is a lot of IR in our environment, need to modulate and error correct
for this.
- Can be finicky getting the proper range for the beacon
- Can be finicky getting a highly directional sensor!
Heat:
Pros
- PIR sensors are common, work well and are inexpensive
- PIR can be very directional if desired
Cons
- How to make the target warmer than its environment?
- How do you sort out different temperature signatures?
Metal:
Pros
- There are a LOT of Hall-effect sensors of many sensitivities
- A plastic or non-ferrous field with metal objects will work well
- Non Hall-effect, simple conduction may be all that is required
Cons
- Range of Hall-effect devices is usually not large.
- Difficulty in finding a work area without conflicting metal signatures
Any other comments? When designing a robotic application you have to
consider the design of the robot, environment, and purpose - change any one
and you render the system inoperable. My favorite is the IR beacon, cheap,
simple and mostly reliable, IMO.
YMMV,
DLC
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Message is in Reply To:
 | | problems met in my project
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| Dear Sir, I am a student who is doing a mobile robot project. Since I am really a freshman in Robotics. So, I would like to ask you to help me to solve some problems met in my project. Please forgive me if my questions are too simple! My aim for the (...) (24 years ago, 17-Apr-00, to lugnet.robotics.handyboard)
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