From what I understand there are pros and cons of both IR and ultrasonic sensors.
Personally, ultrasonic doesn't work for me in my house, I believe it's due to the materials and colours of my furniture. For this reason I use IR more than ultrasonic. However IR doesn't like daylight.

Position wise, I plan to use IR sensors in positions 1 and 2 on your diagram and also a third IR above the front ultrasonic, plus the ultrasonic too. Noting around the back or sides (it can't move sideways so it shouldn't be a problem there), although a rear sensor could be useful when reversing.

It comes down to how many sensors you want and how many ports you have to play with. If you have 6 spare digital ports then 3 ultrasonic sensors could be useful. The same for IR. Just always take in to consideration the benchmark, mine can do around 25 reads per second

I think with all these sensors have covered all angles for navigation, but if you already have two IR sensors on the front at 45 and also the sides with sensors ping, it may not be necessary radar ping, this front sensor could be fixed either ping or IR.
Sometimes the robot approaches a wall laterally as it moves forward because its trajectory is not parallel to the wall next to him. Side sensors are very useful for this case, as the front fixed sensor would not detect the sidewall.
I think that is a mainstay in robotic capacity accurately move our home robots and certainly hope that together we will succeed.

The rear sensors do not see the point if we want the robot to navigate forward, if you are in a dead end can be rotated 180 ° and navigate forward again without turn back. If in any case requires the reverse gear will install a fixed sensor at the rear center to simplify the system.
I made a modification of your drawing to show what would be my ideal platform for navigation (in theory, since I have not proven)
No what would my rate readings per second but I would like to try some seven IR sensors in this configuration:



IR would use two sensors on each side of the robot (4 total) for comparing the readings from both sensors on one side and correct the trajectory to be parallel to the side wall (such as in a hallway)
There was talk in other threads about sailing comparing readings to circulate side by always geometric center of the hall but slightly serious career as "S" or "Z".
With the four side sensors can navigate in the center of the corridor and parallel to the side walls.

Yeah with all the stuff I'm planning I'll bet I'll have to get a second EZ-B. Maybe put one EZ-B just in charge of the sensors.

I still like the idea of using sensors on the sides to help keep it centered when traveling down hallways and such. Would I.R. 's work better for this than Pings?


Thanks guys for replying with your ideas.

It all depends on the surroundings from what I've read. I have black furniture which ultra sonic doesn't like (apparently) so I prefer IR.

The 2 IR sensors on the front corners should help centre it on a hallway in theory, that's all I plan to do on Melvin but the proof will be in the testing I guess.

I've learned from the Roomba and Scooba robots that the IR cliff sensors don't like flat black and other dark colors due to the IR signal not being reflected back to the receiver.

RGORDON i hope to have some sensor data up soon on all types of sensors,i got in my optical bench and making some attachments for each type of sensors.

This is how I plan to have Melvin's sensors



Then, basically...
If the ir sensor on the left detects something it'll turn right.
If the ir sensor on the right detects something it'll turn left.
If the ir or ping sensor in the middle detects something it checks left & right.
Much like my ping roam script but without sweeping.
If boxed in, or too close to an object the whole robot will turn rather than the sweep servo.

So far running on just the front IR he has avoided most things.

Also, with the 2 corner sensors, I'll probably have them centre up the robot in a hallway. If left ir is greater than right ir then the right hand wheels will slow down, causing him to veer off to the right slowly, until the two levels match. The same for the other side.

What do you think is the optimum angle for the corner I.R.'s? 45 degrees? So it will have the best view.

I could make the bumper so the corners could be adjusted, letting me experiment with the angle.

Mine will be whatever looks best on Melvin's base to be honest.

If you have them adjustable, you could always throw on a couple of mini servos and keep them adjustable, kind of like sweeping sensors but a smaller range.

Hmmm...adaptable sensor mounts to suit the situation....cool idea. Depending on the mode of travel or particular location the robot is traversing (hallway for example) one angle may be better than another.

I'm using double sided tape for the IR sensors , once I get the position where I want that works I will drill holes and poke the led sender and receiver through for a cleaner look.

For my main radar I used a pan tilt so it could have angle adjusted too. I figured the side and rear would just be fixed position. I know side sensors are not popular but its to avoid turning right into a object in the main radars blind spot.

Hey Jstarne i agree with your statement like IR sensors can be discovered almost everywhere. If you have a Pc mouse with a red LED or laser it is using IR mild.Thanks!


Sensors Manufacturers

REX you need both type of sensors sonar and IR,while back i made a tutorial on how to use IR and sonars and where to place them for good navigation

MOSTLY YOU PUT IR very low on your design to block sunlight

ON sonars to need to set them high or low ,but now where is will hit stuff like a sofa
ON POSITION to detect corners of wall you need it vertical so that the cone is very small.


A very common design is one set (sonar and ir) in back ,another set on the side ,1 or 2 sets facing forward on a robot and 2 at 45 deg to detect corners

MOST guys call me a sensor expert because i have and used and tested almost everyone made.

Even test some so secret i can say anything about them

Josh,

How many Pings will you be using on Jarvis? Is there a limit on how many Pings you can use due to processor speed and performance issues? I am thinking Questor will end up with (8) Ping sensors.

On the front will be (3):
-one down low to the floor
-one midway up
-one on the top deck.

On each side will be (1): total of (2)
-just above the wheel section (for maneuvering in hallways and such)

On the rear will be (3):
-one down low to the floor
-one midway up
-one on the top deck.

Of course I am still planning on using bumper switches as well.

To all who are following this thread, I would interested in everyone's input on this matter.
Do you think I need more on the sides?
Do you think I need IR sensors also? Or are the Pings enough?

REX you dont need sonars near the floor ,but for that is always IR ,look at roomba robot and neato xv11 all use IR
Second do need IR ,SINCE SONAR wont detect most stuff and same with IR,GLASS;SHINY STUFF,SUNLIGHT

I am looking at changing the IR frequency design to see if it will do better in sunlight

There is a limit on the data transfer between EZ-B and PC. Run a benchmark to find out what yours is since they will all differ slightly.

Real world example, mine...



15 reads per second. That would be just under 2 reads per second for 8 sensors, with nothing else happening.

Writing shows a lot more



Do a benchmark first and work out where the limits are. If you use multiple EZ-Bs you will probably find it's better to spread the sensors over them all rather than have one board for sensors and one for servos etc.

IF you look at my lynxmotion johnny five design it uses 7 sonars and 7 IR'S AND 2 more IRS for floor detect.

A very well made design.

It is my understanding that the L and R ultrasonic or IR sensors should be placed L pointed to the right and right pointed to the left. That way everything is covered. I tried it , and it worked GREAT.

just my 2 Cents.

@josh
What exactly do you mean "once I get the position where I want that works I will drill holes and poke the led sender and receiver through for a cleaner look." How do you do this?

I have experienced that my Ping units will bog down and slow down the robot if I use more than one. Maybe multi-EZBs.