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Thanks for your kind and detailed reply.

> it occurs to me that your system only requires an occasional movement rather than a rapid movement for tracking purposes

Right, actually the system wakes up every 10 seconds to check if the angle needs to be adjusted. It often does not and waits for the next 10 seconds.

There is an opportunity to implement true "hibernation" while the system is waiting to save some more power, but it's not done yet.

> Secondly, the motion system appears to be single-ended and based upon a rope and a stepper motor. It would perhaps be useful to consider conversion to a more rigid system.

Actually there are two geared motors, allowing to control both angles.

Yes, I use simple ropes, the system is stable enough thanks to the counterweight (all ropes are always under tension, making the whole system stable).

> In short, if you have knowledge of your own geometry, have known orientation relative that fixed point, and can before activation determine the TOF distance to your target, and have a GPS fix thus solar inclination at that moment is calculable, then it should be possible to track the target without the need for visual feedback.

My project takes the opposite approach: using a low-cost camera board to avoid having to measure all the geometric aspects precisely.

> In terms of temperature sensing, you can obtain remote temperatures using infra-red linear systems which should be effective.

Good idea, I haven't implemented temperature sensing yet, but I'll look into infrared sensors.

> In terms of safety, laser TOF ensuring no change in distance would ensure the subject is still within the programmed range and an intermediate object hasn't been introduced for combustion.

It may be too late, the intermediate object/person is already heating up by the time we detect it.

> In terms of gathering interest, not sure where you are based in France but I could suggest structuring the system as a public sculpture and holding events including eating food cooked by the system which could involve the additional sponsorship of local wineries, cider, etc. to garner social support.

Yes I'm in France, it would be nice to present the system at such events. For the moment I'd much rather get to work on the technical side.

> Smiles from Sydney. I applaud your work toward the application of technology to social and environmental concern, we need more of this.

Thank you




Taking a computer out of the loop is the best way to guarantee speed and reliability.

Any safety response is going to rely on speed of detection and speed of response. Almost no sensor system will be faster than laser TOF and IMS. They are both very fast and very low power, you can afford to sense at high frequencies and this costs almost no power. Some models may include programmable interrupt lines to further reduce aggregate power utilization by avoiding the need for polling.

In terms of speed of response, anything within 1-2 seconds should be safe. Perhaps having an emergency actuation function in which the array is inverted to prevent convergence (and attract attention as a side effect!) may be safest. You could also cheaply and easily add a siren or audio announcement.

Bon travail et bonne chance!


> Taking a computer out of the loop is the best way to guarantee speed and reliability.

As suggested by pjc50 in another comment [0], a passive safety would be good for this application.

The main drawback being the space required to protect the entire danger zone.

> Bon travail et bonne chance!

Merci beaucoup

[0] https://news.ycombinator.com/item?id=41390704


Well short of an enclosure, the standard for power tools is to project some form of laser mark. Only when the operator verifies the mark is in the correct position should they activate the system. This would be a viable approach for a CNC-shaped array of curves and would not require a complete enclosure, which has various downsides (windage, size, weight, potential for damage, suitability for rough terrain, etc.)


> not sure where you are based in France

I answered your question too quickly, I'm near Clermont-Ferrand, we have several local brewery here.




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