Page 1 of 1

Under the hood of the iRobot S9

PostPosted: June 11th, 2019, 8:30 pm
by vic7767
Just a quick peek under the S9 Roomba reveals a 3300 mAH Li-ion pack, continuation of the modular design of the two drive wheels as well as the brush deck. However the side brush motor is now integrated into the brush deck module.

Also discovered a micro-USB port but so far have been unable to observe any serial port data activity.

IMG_0652.JPG

Re: Under the hood of the iRobot S9

PostPosted: June 14th, 2019, 4:59 pm
by BoxerBoi76
Looks like no room for a larger battery like the i7.

Hopefully third party battery manufacturers can pack more mAH in the same size.

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 8:00 am
by ps0001
I love that they finally put the caster in the back. If they could only figure out a way to automatically clean the rollers of long hair/pet fur, this thing would be unstoppable. I think some of the Samsung robots purport to do this, but I don't know how effective their mechanism is.

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 8:49 am
by RTC
ps0001 wrote:I love that they finally put the caster in the back.

I think the only reason the caster is there is because when the extractors were moved from the center to the front, there was no room left at the front for the caster. :) All it does anyway is act as a speedometer pickup for the machine, so it doesn't really matter where it is.

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 9:05 am
by rotorwash
I love that the caster is in the rear. Mine hasn't needed to be cleaned yet while the ones in the front need to be cleaned daily. Not sure about the speedometer pick up

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 1:17 pm
by Julian
rotorwash wrote:I love that the caster is in the rear. Mine hasn't needed to be cleaned yet while the ones in the front need to be cleaned daily. Not sure about the speedometer pick up

Yes. I've had problems with fluff gathering in the front castor on both of my very old Roomba 560s. I don't have to clean them every run but if I leave it for long enough the whole robot goes crazy because the fluff builds up enough to block the optical sensor that is trying to take the speedometer readings, it doesn't seem to quite know how fast it is moving and starts stopping and starting and moving very jerkily plus making strange course changes that I don't usually see it make. My house is almost all carpeted which is probably harder on the caster in terms of fluff intrusion. I would have thought that having the rollers at the front cleaning a patch of floor before the caster gets dragged over it would significantly reduce the rate of fluff intrusion. Good to hear that that seems to be how it is working out in practice.

Re Vic's initial post, I'm very glad to see that iRobot has to a large extent retained the modular design principles. Definitely a good thing in my view. My old Roombas have been a joy to work on of the few occasions when that's been necessary.

- Julian

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 1:37 pm
by RTC
rotorwash wrote:Not sure about the speedometer pick up

That is why it is half white and half black. An optical sensor converts the cycles of light/dark to digital pulses that the Roomba uses to measure speed & distance moved, just like the pickup on your car's axle is used by the speedometer & odometer on the dashboard to measure speed & distance moved. Older cars used a geared pickup and mechanical analog coupling, most modern cars use a magnetic pickup that generates a series of digital pulses (not much different than the pulses generated by the Roomba's optical sensor at the caster).

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 3:30 pm
by vic7767
Both the i7and S9 castor wheels are of a single color (Black) they do not provide the stasis function that we are used to on the earlier model R3s and most R2s.

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 4:45 pm
by RTC
vic7767 wrote:Both the i7and S9 castor wheels are of a single color (Black)

Interesting! Its probably just a physical support and they estimate speed off the main wheels or something (they still need the info)... Or perhaps the new caster is only all black in visible light and light/dark in IR (which might be more tolerant of dirt on the wheel).

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 7:03 pm
by jdong
RTC wrote:
vic7767 wrote:Both the i7and S9 castor wheels are of a single color (Black)

Interesting! Its probably just a physical support and they estimate speed off the main wheels or something (they still need the info)... Or perhaps the new caster is only all black in visible light and light/dark in IR (which might be more tolerant of dirt on the wheel).


They seem to estimate speed based off an optical mouse like IR sensor now that points at the floor. Though the 980 had color coded caster wheels there was no optical sensor in there.


Sent from my iPhone using Tapatalk Pro

Re: Under the hood of the iRobot S9

PostPosted: June 15th, 2019, 7:56 pm
by RTC
jdong wrote:based off an optical mouse like IR sensor now that points at the floor.

Hmm, I wonder if you might need a "Roomba mousepad" carpet installed in your house :) :) :wink: :lol: :lol:
I always seem to have problems with optical mice if I don't have a mousepad...

Re: Under the hood of the iRobot S9

PostPosted: June 17th, 2019, 9:39 am
by ps0001
jdong wrote:
RTC wrote:Interesting! Its probably just a physical support and they estimate speed off the main wheels or something (they still need the info)... Or perhaps the new caster is only all black in visible light and light/dark in IR (which might be more tolerant of dirt on the wheel).


They seem to estimate speed based off an optical mouse like IR sensor now that points at the floor. Though the 980 had color coded caster wheels there was no optical sensor in there.

I don't know where they got this information, but the IEEE article on the 980 implies these newer robots use a combination of input from the optical sensor, odometry, and an IMU to track relative position, then visual input to counteract drift. I think the caster wheel/"stasis" sensor was only ever used to monitor whether the wheel was stuck. In the old OI spec, data from the stasis sensor is just a single bit.

Re: Under the hood of the iRobot S9

PostPosted: June 17th, 2019, 3:01 pm
by fufu
Somewhere I read that the S9 is using a 3D sensor at the front. I think this was something iRobot mentioned. Is this really something new or different from the standard IR diodes in the front?

Re: Under the hood of the iRobot S9

PostPosted: June 17th, 2019, 3:03 pm
by jdong
fufu wrote:Somewhere I read that the S9 is using a 3D sensor at the front. I think this was something iRobot mentioned. Is this really something new or different from the standard IR diodes in the front?


I suspect it’s LIDAR or some sort of pulsed IR ranging system.


Sent from my iPhone using Tapatalk Pro

Re: Under the hood of the iRobot S9

PostPosted: June 18th, 2019, 11:29 am
by bytemaster0
Most likely just analog/ranged IR to determine distance. Highly doubt it's LIDAR, no spinning parts, and it gets smacked pretty hard, so it'd have to be something pretty solid state. It really doesn't seem much better or smarter than what the i7+ already has, but maybe I'm wrong on that. Maybe it's using that while constructing images of corners to improve upon what the vSLAM algorithm can see.

Re: Under the hood of the iRobot S9

PostPosted: June 18th, 2019, 11:48 am
by jdong
LIDAR doesn’t have to imply a spinning turret. It just has a much finer field of view compared to IR ranging using a diode/lens. It depends on whether they wanted accurate range readings on things at a distance or things close by, respectively.

But considering they kept the camera, I would also assume the “3D sensor” is for not ramming into things up close, which likely means they simply enhanced their IR sensors to add a ranging capability probably by pulsing.

Re: Under the hood of the iRobot S9

PostPosted: June 19th, 2019, 12:20 am
by bytemaster0
jdong wrote:LIDAR doesn’t have to imply a spinning turret.


Absolutely fair point. I agree, most likely updated IR sender/receivers.