Comment by ErroneousBosh
22 days ago
> > a stuck mirror
Detect the mirror being stuck and shut the beam off. Easy.
Hint: how bad would it be if the MCU in your gas heating boiler latched up and wouldn't shut the burner off? How is this mitigated?
22 days ago
> > a stuck mirror
Detect the mirror being stuck and shut the beam off. Easy.
Hint: how bad would it be if the MCU in your gas heating boiler latched up and wouldn't shut the burner off? How is this mitigated?
This was addressed in the original comment:
> Additionally, no LIDAR manufacturer publishes beam-failure shutoff latency. Most are >50ms, which can be long enough for permanent injury
You should be able to do it way faster than that.
Pressure switches, flow sensors, mechanical flame detectors, power supply monitoring, watchdog timers, and XX years of Honeywell or whoever knowing what they are doing.
So yes, a mirror trip reset is probably a good start. But would I trust someone's vision to this alone?
> Pressure switches, flow sensors, mechanical flame detectors, power supply monitoring, watchdog timers, and XX years of Honeywell or whoever knowing what they are doing.
Nope, nothing as complicated as that. You're close with the watchdog timer.
The solenoid is driven by a charge pump, which is capacitively coupled to the output of the controller. The controller toggles the gas grant output on and off a couple of times a second, and it doesn't matter if it sticks high or low - if there's no pulses the charge pump with "go flat" after about a second and drop the solenoid out.
Do the same thing. If a sensor at the edge of the LIDAR's scan misses a scan, kill the beam.
Same way we used to do for electron beam scanning.
>> if there's no pulses the charge pump with "go flat" after about a second and drop the solenoid out.
>> Do the same thing. If a sensor at the edge of the LIDAR's scan misses a scan, kill the beam.
Sounds like a great plan, but I question the "about a second" timing; the GP post calculates that "about a second" is between 4X and 10X the time required to cause damage. So, how fast do these things scan/cycle across their field of view? Could this be solved by speeding up the cycle, or would that overly compromise the image? Change the scan pattern, or insert more check-points in the pattern?