Manuevering a Home Enviornment

[airman00]

Which sensors will be the best suited for a home environment. I have used IR sensors before but they are not really precise. I need to be able to detect when my robot is too close to an object or a wall( less than 6" away).
Will IR be suitable, or will I have to go with sonar. The reason I don't want to go with sonar is because the detection area is very wide and sonar is really expensive. IR is cheaper but not accurate readings.
Can IR detect ranges of 6" or less accurately. Also, will the IR sensor be more accurate for some things in a home environment(different color objects)?

[D0n]

I'm thinking that (mentioned in previous posts) those low powered radio transmitters (dog fences) could be plugged into the ground on your household wiring, and turn all your houses existing wiring into a contianment feild. the strength and position of the feild could be mapped by software....
combine that with ir, sonar, and bump sensors.....

[TimMooney]

Which sensors will be the best suited for a home environment. I have used IR sensors before but they are not really precise. I need to be able to detect when my robot is too close to an object or a wall( less than 6" away).
Will IR be suitable, or will I have to go with sonar. The reason I don't want to go with sonar is because the detection area is very wide and sonar is really expensive. IR is cheaper but not accurate readings.
Can IR detect ranges of 6" or less accurately. Also, will the IR sensor be more accurate for some things in a home environment(different color objects)?

Cats use whiskers for this purpose. (In the dark, anyway.) I haven't tried this, though I have thought about it a little. One advantage is that whiskers detect narrow things (e.g., the legs of a tray table), from which a reflection-based sensor might not get enough signal. Also, a whisker is pretty simple to implement, with music wire, screws, and staples; and it's output is easy for electronics to understand. (In the implementation I'm thinking about, it's basically a switch.)

Tim

[D0n]

my idea for bump sensors is similar to your wiskers....i'm running a spring through a wire loop...when the spring hits something, it'll bend and contact the wire loop completing a circuit....

[elixier]

You can enhance the accuracy and the range of the IR by using the role of modulation.
this can be done with the help of 555 timer and the TSOP 1738.
the 555 timer generates the 38KHz signal and the same is received by the TSOP 1738 which has the filter for having only signals which are of 38 KHz range and so it detects the obstacle.

http://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/January2006/CI-Jan06-02.pdf&title=IR%20Burglar%20Deterrent
http://img254.imageshack.us/img254/9913/555tsopfn3.th.gif (http://img254.imageshack.us/my.php?image=555tsopfn3.gif)

The circuit diagram is a sunder

[mhotze]

I use an ultrasonic range finder, see my site: http://home.wanadoo.nl/m.hotze/robotproject/. It's amazingly accurate, although it needs attention when approaching a wall from an angle. I'm now programming the robot to have a look around (meaning turning the robot) after a couple of steps to check for objects nearby. It still has some difficulty with small objects like chairs. I think it needs to have the sensor mounted on a servo, so that during walking, the sensor can be moved independently from the robot.

[HakBot]

airman00,

Check out the MaxBotix modules. http://www.endurance-rc.com/sonar.html They are fairly easy to use and accurate. You do run into limitations with sonar however. Like mhotze mentioned they have trouble with certain surfaces like angled walls and small objects. I've noticed that my car sometimes bumps into the wall if it comes to it at a very low angle. A good strategy would be to combine several types of sensors.

I currently I have 3 of these modules mounted on my r/c car. I'm trying to make it navigate through my house like you are but at a much greater speed.

[Auckland Neil]

If you have a lot of money to blow, look at the SICK range of laser-scanners. These are intended for industrial applications - but they are very adaptable. Also very pricey, unfortunately.

Has anyone tried an IR scanner?

[D0n]

Hey guys I know the cat story is a little over the top....but seriously...what do you do to make your robots survivable and safe in an unpredictable world?
I don't believe sensors and software can make a system foolproof.
for my project, I'm doing the following:

body panels have a styrofoam "crumplezone" to absorb impacts and improve weather sealing.

some systems have seperate power supplies....

servos have failsafes....

I'm working on my bot to have three modes of control....

low level reflexes that react directly off some sensors to increase survivability (ie, bump sensors will trigger a pull away response like your hand will react to a scald). if everything else fails it'll still try to not run anybody over or fall off a ledge).

semi autonomous functions that will allow it to react to an obstical in it's path while still following the operators general directions...meaning it will adapt. (when I'm able to afford to hire somebody smarter than me to make it work, the goal is to have a servo mounted laser (rangefinder) & compas mounted beside a servo & compass mounted video camera, that will use triganometry to calculate the laser tag, relative to the video camera's position to track and follow objects.) meaning sonar and ir sensors will tell the computer to assume control long enough to get around something that gets in the way while the camera keeps it's eye on the target.

radio and wireless internet connection to allow remote operator to drive it.

with all our senses, we still have to heal from mishaps.
the cat survived it's bath.....can your average robot survive getting pee'd on and then dunked in warm soapy water? would I have gotten electrocuted? if it hits the wall, will the wall get damaged? what about the bot?

I worry about bumps wrecking my hd on my laptop....

[shimniok]

This is totally talking thru my hat but... I have this crazy notion that a person could use the capaciflector concept for this. It's basically half a capacitor with an emf reflector behind it (and the neat thing is that the case can actually be the sensor, kind of elegant)... I haven't yet tested this out but was thinking this might help with sort of a general situational awareness for a large home bot.

The home environment is so complex... it isn't just a bunch of walls and 8' tall boxes. :) How do you detect a coffee table for example? What if the top is glass? How do you avoid the short ledge in front of the fireplace? Etc. So many different materials, etc. My thought too was a boat ton of IR sensors all around the case if the capaciflector doesn't work. They aren't super of course... lots (LOTS) more experimenting to do on my part. *shrug* Wished I knew more... so much more.

Best of luck!

Michael

[HakBot]

Well between the cat's visual sensors, wisker sensors, touch and smell sensors....not to mention the 5 sensors I have we were unable to avoid, an incident.....my cat needs a bath....

hilarious don.!

[Mark]

My robot mixes the results from IR and Ultra sound sensors.

Basically I look at the averages of the results and with in certian limits decide which is more likely to be accurate than the other.

You could of course "mix" the results using Kalman filter