Hello,
I wanted to add the feature of obstacle avoidance to my 250 quad but most of the people doing this use Arduino Mega or some similar board along with sensors to achieve this. I have a multiwii on my quad and adding another board will add atleast more 500-1000gms of weight to it which my quadcopter wouldnt be able to bear. So is there any way by which I could modify the multiwii itself to support this feature? If yes, please tell me how.
Thanks 

Arduino board and (ultrasonic sensors)/(sharp IR sensor) wont add much weight to your quad......!

But still it might fall short of power and it's performance might decline. Can I use my multiwii itself?

See The drone showed in Intel Conference. They have made a 3D camera named Intel Real Sence. Using it, with companion computer which can able to do video processing like Intel Edison or Gallelio or Raspberry Pi 3, you can achieve this. Using ultrasonic or IR sensor, you will still have some error or delay. And no, Multiwii does not support this. You have to use Pixhawk and send data via Serial data bus to do whatever pitch, roll or yaw or second which will be little easier that to direct give PWM output ranging same as your receiver and use PPM encoder to convert it to PPM-SUM and then use both buses to send data. Here you will need to insert another computer like Arduino to choose between two signals from that computer or receiver. And you can make it.
Hope this helps.

But then how about something like Arduino pro mini or similar board? That is a small board and its weight wont affect it much....

Darshan, if you are using any 3D camera like real sense then you need good computer which will have desktop CPU performance and can do video processing. For this, Intel Edison will be best. It has Best GPU in all micro-controller. If you just want to use Arduino, then you have to use IR sensors, in large quantity. Just 4 sensors cannot give you complete avoidance. You need Arduino Mega for it. I would prefer Raspberry Pi as it has desktop like architecture and all languages support. You can use IR sensors and give PWM outputs for throttle/pitch/roll/yaw which also can be used with multiwii but I will suggest Pixhawk. Also take a note that, your Arduino's timing and timing of Flight controller must have to match or should have similar. You need to program for that, and to match it your Atmel Processor may hear up. Use small heat sink for that Arduino's Atmel processor. Your 250 quad cannot equip this, you need minimum 450 quad or 550 hex highly recommended. 😊😊

Quote from: Inv3nt0r on May 03, 2016, 09:23:44 PM
You can use IR sensors and give PWM outputs for throttle/pitch/roll/yaw which also can be used with multiwii.

Can you explain a bit more on this as I am a beginner?

brother you wont need any highend stuff if you want to stick to basics you can just use adriuno and some sonars if you want 3d mapping and stuff you can use raspberrypi with kinect and all to do that follow the below link :
http://www.instructables.com/id/Autonomous-Cardboard-Rasberry-Pi-Controlled-Quad/

http://www.flitetest.com/articles/quadcopter-obstacle-avoidance-system-using-arduino


yes you can use multiwii for the same purpose but you need to see how many i/o pins are free from the multiwi v2.5 and make changes on the board although i doubt it would be able to efficiently function and its made to handle both calculations of sensors and copter control it is always better to keep them both separate

I wanted to use the same multiwii board but now that I need a different one, I think I would go for UNO as I can use it for other projects also and its cheap(mainly its cheap and I wont need to cry if it gets damaged). I was thinking about ultrasonic sensor which is available on ebay(Rs 100 per piece).
Btw how much does an UNO board weigh?

Quote from: cyberhack on May 03, 2016, 09:49:16 PM
brother you wont need any highend stuff if you want to stick to basics you can just use adriuno and some sonars if you want 3d mapping and stuff you can use raspberrypi with kinect and all to do that follow the below link :
http://www.instructables.com/id/Autonomous-Cardboard-Rasberry-Pi-Controlled-Quad/

http://www.flitetest.com/articles/quadcopter-obstacle-avoidance-system-using-arduino


yes you can use multiwii for the same purpose but you need to see how many i/o pins are free from the multiwi v2.5 and make changes on the board although i doubt it would be able to efficiently function and its made to handle both calculations of sensors and copter control it is always better to keep them both separate

I agree. Nice posts on that link. Its like pay more and get more. If you spend more on high end products, you will get better results. Sonar is also a better idea, but it will suitable for low speed multirotor. It will not useful for planes or racer quads. But it's great for normal Multirotor or proof of concept. all will depend on the algorithm with all sensors and delays and timings in all system. you may need to change Multiwii to stay on last input if no further input has received.

You're attempting this with the wrong quad. 250 is meant for speed and acrobatics, not stability and payload capabilities that you require.

I have researched this topic for my mini project and people have implemented it using a 450 quad and arduino with ultrasonic sensors. Will be very hard to implement on 250.

Darshan y do u want it on a 250 quad There is no need for this system on a 250 quad 250 are meant for racing also its but obvs that these system will take some payload although you can put them on it not a issue well obstacle avoidance is for some kinda of projects and not for hobby flying also use good sonars nt all sonars have good range and latency time is more 

It would be a temporary thing and mini quads crash more often than bigger quads as they are much faster. So I thought this could minimize the damage cause every time I crashed. I thought that this could be possible. But if you say so I won't do it....