I've been playing with one of those indoor model helicopters. Mine is called the 'BladeRunner 2', but I expect that it will be sold under other names as well - blade diameter 300mm.
I'm very impressed at how easy it is to fly in a modest sized room, and it also seems to survive unscheduled arrivals.
So, I wonder about a robot version of the same. The take off weight is ~
66g, which gives a flight time of ~ 10 minutes, so there seems some scope for lifting more weight at the expense of reduced flight time.
We need to add enough sensors to determine position within a room - presumably IR or ultrasonic. We also need to determine heading (it has a gyro to stabilise the yaw axis, but this is more of a trim and tends to drift). The challenge is to do all this for near zero weight.
Next of course comes the onboard camera, and then there are even smaller helicopters ...
I think you'll have your work cut out with that Heli. I've got the one before it, and whilst it's a bit of fun it's really not cut out for modding, it simply don't have enough lift (A couple of sensors and it'll never get off the ground). Check out this forum for heli-bot projects...most impressive!
These counter-rotating blade helicopters make the flying easier, so it stands to reason it would be easier to automate the thing. I've had it on my to-do list, but like so many things...
As long as you keep the weight down it should be doable, so the weight is the real challenge. The Bladerunners already use lithium batteries, but maybe you could find a more efficient motor (and a higher price) that would give you a better weight-to-lift ratio. Your electronics will probably need to be constructed on a small carrier without a PCB, as even a small PCB would add too much weight.
Look for segments of the body you can remove or cut out to give you a little weight benefit.
There are lighter LiPo batteries available. I'm not so sure about the motors (it uses two for the main drive, plus a really small one for the tail rotor). The body is foam.
You need to determine your approx distance from walls in six directions, but if you assume that the room does not change in size whilst you are flying, then you only need three measurements. It looks like a good application for ultrasonics, but using multiple sensors adds weight (A single Tx or Rx is
3g, SRF04 is 10g) I wonder about a single sensor pair, with some kind of rotating 'horn' to provide directionality.
PCBs don't have to be 1.6mm thick ! You can even get flex pcb stuff for prototyping, which is nice because you can bend to fit in available space.
Still looking for ideas about heading 'lock' - a magnetic compass near high current stuff doesn't look ideal ...
Dave
Gord> These counter-rotating blade helicopters make the flying easier, so it
I have the first version (BR2) - I think the critical difference is in the two counter rotating main rotors - the tail rotor points up and down, and merely tilts the body for forward/backwards. I haven't verified that there is actually a gyro, but from the behaviour there must be one.
Flying is fine unless you spend too long near an obstacle - if you do there seems to be a circulation set up that sucks you towards doom ...
I would think that you should keep as much of the electronics off-board as you can. Perhaps put a surface-mount LED infrared beacon on the heli, and determine its location from two (or more) cameras watching from the ground. If there were 3 beacons on the helicopter, then all 6 DOF can be calculated.
I've seen plenty of projects using the LED beacons at universities. They are use as a 3-D pointer for Virtual Reality setups.
Another idea, which doesn't seem as good is to use the noise the helicopter makesas a means of location. An array of 3 microphones could be used, and this wouldn't requiring any modifying of the heli at all!
If the sound from the helicopter doesn't put out a distinguisable element (a "ping" type sound) then you can identify it with a computer. If it doesn't put out such a sound, perhaps some mechanical means can be added by putting someting that touches a gear and generates a sound.
The idea is to calculate the time it takes for a sound to get from the heli to each of the 3 microphones. Each mike would calcuate a distance from the time, and narrow the location to the surface of a sphere around that particular microphone. The final determination is made from the intersection of the 3 spheres.
I am not certain how you do this without knowing the time the sound first eminates from the Heli. Though, I am sure there is a way. But, one source of that time could be electrical noise generated from the brushes on the main motor. By comparing that electrial static burst to the time of the sound, you can get distance.
However, this would only give you a location, and not the kind of detail you would need to truely fly a helicopter unless it had significant on-board stablization ability. I don't see any possibility of extracting roll,pitch or yaw information from sonar.
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