[Dprglist] First BBR implementation and some questions

[Karim Virani]

Many of y'all will remember this super-speed finger bot - 1ms loop time or
shorter:
https://www.youtube.com/watch?v=-KxjVlaLBmk&ab_channel=Hizook



On Sun, Oct 31, 2021 at 5:42 PM Karim Virani <pondersome64 at gmail.com> wrote:

> The loop time is entirely up to you. The question is, how quickly does
> your robot need to react? That depends a lot on physics - on scale. It also
> depends on the needs of the most timing-sensitive (non-ISR) sensors you are
> managing, and how you service them.
>
> We don't even have a set loop time since we are using Android on most of
> our robots. Our loop time varies a lot, but is generally under 50ms. We
> normalize all our timing to seconds and our math looks like normal physics
> calculations vs. something short-cutted to a fixed timing loop. Granted,
> this is not a common approach in microcontroller-driven hobbyist robotics.
> Deemed wasteful of processing cycles by many.
>
> On Sun, Oct 31, 2021 at 5:31 PM Thalanayar Muthukumar <tnkumar at gmail.com>
> wrote:
>
>> Makes sense Karim, that at all times, the robot is interruptible by
>> higher priority events.
>>
>> Is 50ms ok? Or is 20ms desirable?
>>
>> Regards.
>> - Kumar
>>
>> Sent from my iPhone
>>
>> On Oct 31, 2021, at 5:26 PM, Karim Virani <pondersome64 at gmail.com> wrote:
>>
>> 
>> I agree with Doug, you should never have blocking code unless you can
>> dedicate a separate thread to it apart from your main loop's thread.
>>
>> And not to start up the whole debate again, I personally vote that there
>> is no use for ballistic behaviors. I treat them as an academic construct.
>> There are plenty of uses of objective-oriented and terminating behaviors -
>> including those where the objective is to last for a certain amount of
>> time. But they should still be interruptible and cancellable by higher
>> priority behaviors.
>>
>> On Sun, Oct 31, 2021 at 5:08 PM Doug Paradis via DPRGlist <
>> dprglist at lists.dprg.org> wrote:
>>
>>> Kumar,
>>>     I always pass through the loop. So a 1 sec backwards maneuver would
>>> use a loop counter with a disengage value of 50 for a loop time of 20 mS. I
>>> am not using a multitasking framework, which opens up other possibilities.
>>>
>>> Regards
>>> Doug P.
>>>
>>> Sent from my iPhone
>>>
>>> On Oct 31, 2021, at 4:54 PM, Thalanayar Muthukumar via DPRGlist <
>>> dprglist at lists.dprg.org> wrote:
>>>
>>> 
>>> https://youtu.be/fuFamNWyXc4 (~15 sec)
>>>
>>> 20 times per sec
>>> - default behavior - go straight forward, green headlights
>>> - higher priority behavior - light sensed, turn left, red headlights
>>>
>>> My understanding of BBR is that there should be no state maintained.
>>>
>>> Question - If we trigger a ballistic behavior (e.g. go straight backward
>>> for one sec), is it ok to not return to the loop every 50 msec?
>>>
>>> Or is it preferable to maintain state and count 20 times for getting
>>> duration of 1 sec?
>>>
>>> Regards.
>>> - Kumar
>>>
>>>
>>>
>>> Sent from my iPhone
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