RE: [Paparazzi-devel] RE : distance measurement for landing. (EldenCrom) from Chris

[marcus.wolschon]

On Thu, 12 Nov 2009 19:39:25 +0200, "gisela.noci"
<address@hidden> wrote:
>> I'm thinking about using ultrasound for autonomous landing
>> in a paraplane. It can move as slow as casual walking -speed
>> in landing. Thus it does not need the sample-rate nor the
>> maximum meassuring-altitude required for a fast fixed-wing
>> aircraft.
>
> From how high do you want to detect ground? Does the paraplane 'swing'
> about under the chute?

Very low center of gravity and extremely stable in any wind that will
allow for safe autonomous flight.

> Excessive Roll and Pitch angles are a problem, as the
> ultrasound is VERY directional; a 10 to 15 degree roll will cause loss of
> ranging data, since the beam simply reflects away at the ground incidence
> angle.

Good point. I'll have to consider this.

> This is worsened if the ground being ranged is hard and smooth with
> little specular reflection. If you can keep roll and pitch to under 8 or
so
> degrees, it will work for you.

8 degrees is not much. I guess I'll have to think about a mounting
that keeps the sensor vertical without swinging around.


Marcus