Max Rate Question for Brushed


#1

I have been working on my understanding of pids, rates, and expo and have just watched a video from StingersSwarm on dream rates and I am wanting to work on my rates to find that sweet spot for my 90X.

This is what I am flying atm having only changed the PIDs and expo at this point.

In his settings, the range of his rates went from 800 to 1226 on a brushed quad. Is there a max rate level for 8.5mm coreless motors on a 750 25c 1S battery?


#2

Search snake fpv YouTube, he just did a vid on investigating ideal rates. Its a personal thing, he compares it to getting your mouse set right in fps gaming.


#3

My question was more if my motors could handle rates at or above 1000 for the times I would potentially hit full throttle.


#4

Your rates in degrees per second is the maximum rate that Betaflight will allow your quad to rotate around a particular axis (360 deg/sec meaning one complete rotation per second). So it is not directly related to the speed the motors spin, right? It more controls the speed difference between the motors on one side and the motors on the other side.

I guess there would be a limit to how much that difference could be, which would limit your max rate, but you’re not going to burn out your motors by setting your rate high, if that’s what you are asking.

I personally am flying my whoop with 7x16 motors with pitch/roll rates of 1100 deg/sec, with plenty of expo for fine control around the middle of the stick range.


#5

I just put the rates to 1100 deg/sec and hoolleee shyte! It is a whole new quad and man, it also ups the adrenaline rush when you can fly like that.


#6

A run on 1100 rates (forgive the raw footage) And you get to meet Darth Deciduous.


#7

I will certainly say that I am glad to have learned the hows and whys of rates. I burned through quite a few batteries on these settings and I was amazed at the improvement of my flights compared those prior to the enlightenment.

I have not tried these settings with arco trainer but I have a pretty good idea that it will make all the difference in improving the handling that has been eluding me.


#8

I use thumbs, vs pinching. I prefer medium rates (600-800) and then even lower rates for racing (450-600) …Too high of rates on a brushed quad i felt did more harm than good for me… It would flip so fast, and when i would “catch the flip” the brushed quad didnt have a decent feeling of authority on the path it was taking due to lack of torque with brushed motors, creating a feeling of instability in the air. Not to mention its very easy to overshoot your flips, causing overcorrecting which all in all looked and flew like dog crap…

i call fast flips “flash flips”, cuz they tend to be so fast it just looks like a flash on the screen.

So i said, screw it, ill stick with a smooth flight style with medium or low rates. Now all my quads are all far more controllable, and all flips actually look like real intentional flips lol


#9

I’ll take some logs for you guys to show what happens when you set unobtainable rates. Error builds up, recoveries suffer, and the pid controller is still trying to catch up on your last move preventing it from being ready for the next. Most of the “feeling” you like from higher rates is coming from a more sensitive center and mid stick. Because super rates absolutely flatten this zone, you end up jacking up the max deg/s to get the feel to finally respond near middle. Trust me, you aren’t hitting 1100 deg/s of actual rotation. Try experimenting with putting in 0 for superrates, and jacking up rcrate with added expo to compensate and using reasonable numbers. You’ll find a brushed craft will fly more accurately and you can still get the feel you’re looking for.


#10

Would this be the difference between freestyle and race rates?

I set my rates to 800 and flew it around like normal (race style) and it seemed sluggish, so I went back up to 1100. I would imagine that doing more freestyle would not need high rates but I haven’t gotten to the point of doing flips and rolls, just bobbing and weaving around the trees of my yard.

I am compiling a list of rates I find on Youtube to try out as well.


#11

I fly 1.3 rc rate, 0.7 super, 1.3 expo, for whatever that might be worth. Comes out to 820-860 degrees per second, depending on the FC software and version.


#12

Lol, that’s certainly possible :- ) I can’t tell you exactly what I liked more about the higher rates when I started trying them out, but I think I was trying to be able to do a flip indoors without hitting the ground. I probably should try some other rates again and see what feels good now.


#13

The thing I have been noticing with this is the very strong emphasis on freestyle with how the rates affect rolls and flips, but very little on race-style rates. My skill level is not quite to the level of low altitude flips and rolls and I fly more race style due to skill level and that most of my yard has a canopy.

Didn’t really take a notice until I watched this video on three profiles the pilot uses.


#14

Added to the list. :slight_smile:


#15

So I just ran a few packs with my Silverware roll/pitch rates set to 1100 deg/sec with a rate multiplier of 0.8 assigned to a switch. So 880 deg/sec in low rate mode. I don’t know how many actual degrees per second it is rotating, but it definitely rotates faster with the higher rate setting. Maybe the max is somewhere between those two numbers?

I guess I could take some video and count how many frames it takes to rotate to see how many degrees per second I’m actually getting…

Of course, the actual rotation rates depend on my stick movements in addition to the degrees per second setting on the FC. But whatever I’m currently doing, the rate setting of 1100 vs. 880, at least, does make some difference :- )


#16

Ideally we need to take into account the physical limits of the system in both ability to accelerate rotational rate and the max rate that can be achieved by different brushed systems. Then commanded rotational rate as a function of your natural stick movement and the associated command based on your rate profile should at most match the physical limits of acceleration and max possible rotation rate.

The goal is never to send a command that exceeds the physical limits or error gets accumulated fast. There are some new algorithms now that do exist to put a bandaid on this type of event like transient windup compensation which are active in my fork … so maybe worrying about this is a thing of the past … but I would still like to Co duct a scientific experiment to find the answers.

The alienwhoop v2.1 with blackbox logging and a very select few other brushed boards with blackbox will be an invaluable tool to figuring this out.

I’d also like to add that a lot of this comes down to where you are in your fpv journey. As we progress we want to break into that style of aggressive fast flips or rollsomething near the ground so we up our rates… but eventually the focus shifts to precision in movement … and not about just ripping a flip or roll fast. This is why racing rates are low and freestyle rates by many great pilots are not much higher. If you need to command near 400 degrees rotation - your target stick deflection has a much wider zone with lower rates than high.

I can roll or flip my whoop at speed with less than 2 or 3 feet space and sub 900 rates.


#17

Yeah…I’m not there yet :- ) But I’ll get there eventually!

There are certainly great freestyle pilots with low and high rates. Generally, I like the slower, smother flips and rolls are more fun to watch and experience. The agree that the high rates are a crutch, in a sense, for some things I want to do, and I sacrifice some precision by having too much rate range for a fixed stick throw range. Luckily, I can have a blast flying either way!


#18

^this!!! :smile:


#19

I didn’t really doubt this, but you got me curious (doesn’t take much!) and I remembered to check this out today and thought the results might be interesting to others.

I set up my phone to take video at 240 frames per second and did in-place flips with my Beta 65S Lite (716 motors). I did this with both the low- and high-rate settings, which was still set at 880 deg/sec and 1100 deg/sec.

I counted the number of video frames that the middle 180 degrees of each flip took, so any speed-up and slow-down time at the beginning and end of the flip is ignored.

On the lower rate, I counted about 47 frames. At the higher rate, I counted about 38 frames. That works out to about 900 deg/sec and about 1100 deg/sec.**

So I don’t know what the upper rotation speed limit is for a 65mm whoop with 7x16 motors, but it is not lower than 1100 degrees per second. :- )

** 180 degrees / (38 frames / 240 frames/second) = 1136.84 degrees/second


#20

I’ll dig up my plasmatree logs that show massive error accumulation. Maybe I stated it wrong… it would be more accurate to say that it cannot reach the commanded rotation as its requested without trailing behind pretty bad at such rates. Closer to 900 it can always be where it’s supposed to. :slight_smile: