Hey,

We don't consider mechanical failures while building hobby planes..What happens if any of your motor fails?

I was using HC-SR04 (200 Rs.) ultrasonic sensor along with servo (250 Rs.). So total cost was around 450. If I had gone with the 6 sensors, it would have costed me 1200 Rs. Plus, less component means less maintenance and a lot less programming.  Plus, as I said earlier, this is for slow vehicle only.

Depending on the size of the quad, if you install 8 of the sensors, you might still have blind corners that is what I meant. But more of them better coverage you will have.

Ultimately, what to choose is totally dependent on the specific project. I just added my two cents based on my previous experience.

Thanks.

Quote from: rahimv on April 20, 2015, 10:36:32 AM
We don't consider mechanical failures while building hobby planes..What happens if any of your motor fails?

But yes in a hobby plane the control inputs are given by humans....so in case of a motor failure we do know what to do...GLIDE down to a safe spot...but you cannot just compare it to building an autonomous robot which is programmed to complete its objective...Over here the controller only knows to navigate but doesn't know what to do incase of a motor failure or some other kind of failure!!

Quote from: rahimv on April 20, 2015, 10:36:32 AM
Plus, as I said earlier, this is for slow vehicle only.

And your solution for a slow vehicle is a sensor mounted on a rotating servo?? Think about this...your sensor is pointing on the left side but there is an obstacle on the right....then?
Plus more blind spots too!

I am just trying to give some direction Himadri where you could give more thought. If you have made up your mind using 6 sensors, go ahead and do that way. I am not imposing anything.

I am comparing the motor of your quad with the servo. Not comparing it with a hobby plane controlled by human. And no, if your quads one motor fails, I don't it will auto-correct itself and able land.

Quote from: Himadri Roy on April 20, 2015, 10:46:53 AM
And your solution for a slow vehicle is a sensor mounted on a rotating servo?? Think about this...your sensor is pointing on the left side but there is an obstacle on the right....then?

Try to be polite I have thought of it and it works perfectly in my case. I have written a program where in I measure distance to the obstacles in every direction using rotating sensor. Distance is measured all the time in all the directions (even if rover is going straight). It will not turn left if there is an obstacle on left. I have programmed in such a way that it never happens that rover turns in a direction while the sensor is pointing towards other.

My rover used to run all day in my home with lots of obstacles and without hitting anything, not even once.

Again, every choice is highly dependent on the specific project. Evaluate all the options and make a choice which suits your needs!

Quote from: rahimv on April 20, 2015, 11:40:20 AM
Try to be polite I have thought of it and it works perfectly in my case. I have written a program where in I measure distance to the obstacles in every direction using rotating sensor. Distance is measured all the time in all the directions (even if rover is going straight). It will not turn left if there is an obstacle on left. I have programmed in such a way that it never happens that rover turns in a direction while the sensor is pointing towards other.

My rover used to run all day in my home with lots of obstacles and without hitting anything, not even once.

Again, every choice is highly dependent on the specific project. Evaluate all the options and make a choice which suits your needs!

If you wan to take a criticism as a rude reply so be it!
And to be clear over here we are taking about a AUTONOMOUS QUAD not a land vehicle....

Quote from: Himadri Roy on April 20, 2015, 11:52:40 AM
If you wan to take a criticism as a rude reply so be it!

Wow, what an attitude sir.

Quote from: Himadri Roy on April 20, 2015, 11:52:40 AM
And to be clear over here we are taking about a AUTONOMOUS QUAD not a land vehicle....

Thanks for making it all caps, I could clearly see it now. As if I did not know what I was talking about. If you had shown a little bit of respect, I would have given you full fail-safe Arduino sketch including pin layouts and all (I spent days on making it fail-safe).

Should not judge anyone by count of posts they have made. I am programmer by profession and have over 15 years of experience. Have been doing programming for last 18 years and done amazing things.

But guess what, I am done here. Good luck with your project.

First of all its not my project i gave a suggestion...secondly i just criticized or did not back your suggestion so you started calling me rude (no problem)
And can you tell me where did i say that you are new to this forum or you have less posts than me so you are less experienced than me???  

Quote
Should not judge anyone by count of posts they have made.

QuoteI am programmer by profession and have over 15 years of experience. Have been doing programming for last 18 years and done amazing things.

Great!!
But i am not here to abuse someone or raise questions on anyone's competency in their field!

Increasing number of ultrasonic sensors is not a solution here because overlapping ultrasonic waves makes more complication (else we need to measure one at once but this will delay overall calculation) is not easy for programming(at-least for me don't know your skills) and decreasing will create blind spots(many times already mentioned here).

Ideal no should be six(i think) and then in an infinite loop keep on checking each sensor and storing each value in an array..
Then checking each value for the lowest value(indicating a obstacle) and adjusting the quad to the direction where the sensor has max value (obstacle at the farthest distance than other sensor)

But I think driving the quad autonomously may e the biggest challenge..forward, backward,left and right may be easy but driving it diagonally may be a challenge!

Move just like a plane moves so  only 3 sensors( one in front middle, one front left and one in front right) is enough. To forward direction and just ignore back / sides