Speedy Gonzales

Currently, all speeds, both horizontally and vertically are set to 0.3m/s for the sake of safety in enclosed arenas like indoors and the walled back garden.  The down side is that in the park with the GPS waypoints perhaps 20m apart, it takes a very long time, often over a minute between waypoints, wearing out the batteries in a few flights.

The limitation other than safety is to ensure the down-facing video can track the difference between frames, which means there needs to be a significant overlap between consecutive frames.

The video runs at 10Hz*.  The RPi camera angle of view (AOV) is 48.8°.  With the camera 1m off the ground (the standard set throughout all flights)**, 48.8° corresponds to 80cm horizontal distance (2 x 1m * tan (AOV / 2)). Assuming there needs to be a 90% overlap between frames to get accurate video macro-block vectors, every 0.1s, Hermione can move up to 8cm (10%) or 0.80m/s compared to the current 0.3m/s.  I’ll be trying this out on the GPS tracking flights in the park tomorrow.


*10Hz seems to be about the highest frequency for the video that the macro-block processing can handle without causing other sensor processing to overflow – specifically the IMU FIFO.

**1 meter height is for the sake of safety, and because the video 320² pixels macro-blocks can resolve distance accurately on grass and gravel.  Doubling the height requires quadrupling the video frame size to 640² to get the same resolution required for grass / gravel, and once again, the processing time required will cause IMU FIFO overflowing.


P.S. The weather isn’t as good as I’d hoped to do the GPS tracking flights in the park yet, but I did take Hermione into the back garden this morning to test her increased horizontal velocity changes; she happily ran at 1m/s over the grass, so that will be the new speed used for the much longer distance GPS flights to reduce Hermione’s flight time and hence her and the DJI Mavic’s battery drain.

Dear Remainers and Brexiters alike,

The referendum still needs to be approved in Parliament. We can still stop the process.

Please put aside your personal concerns and consider the impact this will have on today’s youth and generations to come.  The youth voted to remain in the EU – it’s they that we, their parents, guardians, grandparents and family, have failed if we leave the EU.

The majority of MPs are Remainers. Please write to your MPs to ask them put the future of our kids and the youth of today ahead of their personal wishes.  Ask them to vote against leaving the EU. This is the last chance we have to come together and stop the damage to our childrens’ lives for generations to come.

Click to find out your MP’s contact details based on your postcode.

Please, everyone, Remainers and enlightened Brexiters alike, write to your MP – this is our last chance; seize it.

Cotswold Jam – date change – now 2nd July

Due to a double booking at the University of Gloucestershire, we’ve had to move the Cotswold Jam out by a week to Saturday 2nd July.  Current tickets remain valid, but if you can’t attend, please e-mail admin at cotswoldjam.org so that we can free your tickets up for others and return any voluntary donation you gave.

Thanks, and hope to see you there.

Cotswold Raspberry Jam

Cotswold Raspberry Jam

 

Blog membership disabled…

Just a quick note to the few of you who are genuine members of this site that the majority of the 130 members are scammers.  Rather than spending a few minutes mocking and then deleting their attempt to post something pointless on my site, I’m just going to delete them all.

My apologies in advance if I accidentally delete you as a valid and valued member – please let me know if I do.

This should in no way affect anyone’s ability to post comments which I will continue to moderate.