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- Äas pĆidĂĄn 15. 03. 2017
- Teardown of the RoboMaid RM-770 Automated Robot Vacuum Cleaner
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We had one a few years ago but had to get rid of it. It became self aware & started making lewd comments to my wife. We caught it trying to copulate with the washing machine too :(
*Bloody gold!!*
You folks should try counseling...
lmao
I bet it fought with your pet dog too.
LOL
The coding of IR signals is similar to ones Roomba uses. The signal is coded in a way that makes possible to detect both signals at once. It's basically a logical OR operation. The short signal encodes 0 and the long one encodes 1. When you overlap both signals then the long one "overrides" the short one. So in case of the virtual wall, you have "11001000" on one blaster and "11000100" on second one and when the robot is in range of both blasters then it receives "11001100" and knows its relative position regarding the virtual wall.
For the Roomba, all the IR signals are documented by iRobot.
Roomba's Virtual Wall/Lantern is a little more intelligent than that in the video. At least for some series of Roomba it uses RF receiver to turn itself on. In case of Virtual Lantern mode Roomba can also request different operations from the Lanterns like the identification or request for disabling the Virtual Wall and enabling the tracking blasters. The Lantern is used for slicing whole flat or house area into subareas (for example different rooms) and Roomba cleans only one room first and then requests one of the Lanterns to disable the wall and enable tracking blaster, which then allows the robot to go straight to another room. The Lanterns also have left and right side and Roomba remembers the order of Lanterns it goes through so it knows how to go back to the charging station.
The charging station in Roomba also uses similar set of IR blasters. But it doesn't have "dead zone" in between left and right signals. All 3 signals (360 at the top, and left/right zones) in charging station are synchronised and work the same way as in the Virtual Wall in this video. They have different bits set. In the middle the Roomba receives both left and right zone signals by logically OR-ing them.
The 360 degree IR blasters on charging station and virtual walls/lanterns are used for "do not enter" zone. This prevents the robot from bumping into the side or back of the stations. In case of the charging station only going from front is allowed (by OR-ing the "do not enter" signal with the zone signals from the front emitter).
On the Roomba, the 360 degree sensor is used only for receiving signals from other stations and also probably from the IR remote (that's why the IR remote often doesn't work properly near the charging station and virtual walls/lanterns).
7:00 on the roombas those piezo elements are used to detect dirt like small rocks and such since the micro inside it can detect the sound of small socks hitting the plastic so it knows "ok i need to clean this area abit more" kind of deal.
Plausible.
hook power up to the pcb the pinouts was on the silk screen and tap on em and watch it on the oscilloscope and you will see :)
When a tiny rock or simular hits them they will emit a spike on the "R-D" or "L-D" pin that the micro can pick up.
But why do they need two piezo for that? Maybe the two identical PCBs reacts different (send and receive) if they connected together?
It's more or less a sterio microphone system.
When the robot vac detects let's say a rock or simular it makes a cirkle around that area to clean that spot extra much.
Depending on wich piezo that detected the strongest "tap" sound will tell the micro if it should start the cirkle to the left or to the right of where it's currently going.
Here is a picture of a roomba:
s.hswstatic.com/gif/robotic-vacuum-13.jpg
Notice the sensors are called as "Dirt sensor"
Think you can see this in action if you search youtube for "roomba dirt detect"
The 4 pairs of IR receiver + emitter is to detect steps or edges of your floor (so it won't fall down the stairs).
The bumper in the front is to detect when it's hits the wall. No timing "smart" things.
It doesn't count anything, it's just going on until it detects the beacon from the base. The 360 len is to prevent it from hitting the towers & base.
The "IR plastic" is just for the "cool" look. That's it.
You're giving it too much credit. It's dumber then you can imagine.... Basically, it's just goes on until 1) it'sâ hit a wall 2) a stair detected. Then it just wait for the battery to die, then returns to base for charging. Oh, and it avoids virtual walls.
I've had a Roomba 960 for a few months. It's incredible, way exceeded what I thought it would be able to do (and I don't have a robot friendly environment). Isn't fussed by loose cords on the floor, cluttered (and changing) environments, loose rugs, stairs, pets, etc. Very thorough and vaccums better than I can do by hand. It did once escape to the outdoors after someone left the front door open (it can climb a surprisingly high obstacle) and I had to free one of the wheels that got jammed with dirt as a result, but it's been running perfectly since then. Couldn't go back to life without one.
I know someone that has one of the brand name robot vacuums and it works really well. Because it vacuums the room each time you leave the house you get a pretty great result. I was impressed.
As far as I can see... 99% of these (perhaps even some of the Roombas) literally just do a random walk, and the IR tells them the direction to return back. Zero mapping/memory.
I'm saddened by the lack of technology...
My Roomba 8-something does the random walk - I am only impressed its movement in a straight line - on DTU we tried doing deduced reckoning but 1/10 mm pn wheel diameter took it off course - looks like it just follows IR
I had a "Neato" bought it for the simple fact it actually mapped the room using LiDAR. It actually scanned the room first then vacuumed the room. Worked great until the it developed some issues 2 years after running every day.
Yes, basically they stop the vacuum motor when the battery gets low, but they still have plenty of power to drive around some more, and continue the random walk until by chance they see the charging station and can drive towards it. That can take quite some time.
The thinking is probably that this dumb device can continue cleaning for several hours while you are away, so that even the random walk will go everywhere at least once. But yeah it would be neat if it was smarter. Like, have a Kinect camera on there which actually creates a 3D point cloud of the room or something like that.
My wife and I are nearly 70 and use one of these constantly, It's very very good, the only problem is the size of the dust, dirt holder being small, we have 3 dogs that constantly bring in grass, twigs, etc.... I needs to be emptied a lot... It lets you know when it's full but still a pain... Other than that it works great...
Deserthunter Mike The kÀrcher RC3000 robot cleaner automatically empties the small bin into a much larger bin in the charging station.
Perhaps something like that would work better for you?
I don't remember the model I bought my wife, but it's wonderful, she loves it. The area that catches is a little small, but it lets you know when it's full and you dump it, no big deal.... So far we really like it....
Thanks Dave, cool to see the some of the inner workings and your scope use.
Love these teardown videos
They're not steppers, they're DC Servos, so that's why it has to count pulses. Also, steppers look different, here you can see the brushes through the cooling slit, but steppers don't have brushes.
15:18 UV Light, supposedly to kill microbes - I switch it off to save battery!
I like how the pulse code of the inferred transmitters is aligned in time. You end up with three codes, the third is produced when the robomaid is receiving from both transmitters.
The UV lamp is a germicidal ccfl mercury bulb. It outputs UVC at 254nm and perhaps even 185nm mercury emission lines, which kill bacteria, although that lens looks like it would absorb most of the shortwave uv... You can repurpose it for erasing eproms, if you wish!
*Its just marketing wank....I guess...*
Roomba owner here.
1. It doesn't count steps, it just randomly searches for home beacon. If it would not find one, it just stop in the middle of the room (and play audible signal)
2. IR emitters/detectors on the sides are for steps/edges/ladder detection.
3. Roomba definitely has some sort of "bin full/overflow" detection. And bin is electrically connected to the main body.
4. One can buy extra virtual walls so they probably not coded for robot (maybe they coded for different model series though)
5. Roomba does not have UV light
As a cleaner it is pretty effective, but it takes too much time to clean brush from hair afterwards
We have a Roomba, it's brilliant, esp. with pets. Def reduces the need to break out the full-size vacuum. It's actually the second one we have, the newer ones clean a lot better. Highly recommended, works well, but differently than just running a vacuum.
I repair the Roomba stuff but never seen any of the knockoff stuff. That is a lot different than the stuff I work on. Thanks for the teardown
I have bought the ilife V7S and I'm really happy with this 138 Euro vacuum cleaner. It can also mop and I really love it.
Compared to these karcher or other expensive ones, it performs about the same. Maybe the ilife will break down faster, but who cares if you can buy 7 of them for the same price as a Karcher.
Ordinary DC Brush motor, stepper motors may be too expensive for this
It reminds me of the "Roamer" robot we had in school circa 1990. That thing used 2 big lantern batteries!
@EEVBlog I had a _very_ similar one. The IR emitter/transistor pairs on the bottom are so it doesn't fall over edges and the UV is supposed to kill bugs. Technologically interesting but they just don't have the grunt to get your carpet clean enough by themselves. Oh and they don't need any idea of where they are or even to be able to see the infrared beacon when it's charging time. They have a search algorithm.
Looks like the IR modules are just repeatedly transmitting an 8-bit ID
C8 - 360 deg beacon
C4 - Wall
F8 - Left homing beacon
F4 - Right homing beacon
and using the different carrier frequencies as a 'incoming bit' and 'data'
The 3 position, amplitude boost, switch to help with SNR on warm days?
:o)
The "EM78P259N" thing is a 8-bit OTP ROM Microcontroller, so they need to put it on sockets ..... And the processor on the top board is not ST Micro, it's STC micro, a Chinese version of 8051 micro
The IR Tx/Rx around the front perimeter are cliff sensors. They detect edges to prevent it from driving itself over the stairs.
Those piezoelectric transducers are used to roughly estimate the amount of dirt being sucked up by the machine. If it goes over a certain threshold, the machine will go over that area again to ensure it got everything. They have the same feature on the Roomba.
My Neato D85 is pretty effective. Not because they have cool Lidar and advanced room mapping, although I'm sure that helps, but because it is "D" shaped and gets in the corners and up against things properly! Some low tech thinking that makes a big difference over the round ones.
I had a Chang-Wang Robo Vacuum like this for a year or so. Used it on the ground floor of my house that is all hard flooring. It was surprisingly effective, but was ultimately let down by the battery pack.
my sister has one similar to this, watching it find its way in the dead zone is hilarious at times. apparently it's quite common for it to either crash into the base or give up just short for some reason
I love the "very quickly" :)
This explains why our Roomba starts shaking it's ass when it's almost docked. Since the dead zone gets smaller and smaller as it approaches. I've always wondered.
It works quite well by the way. (Roomba 650) With three cats it's a very nice thing to have. Not as good as vacuuming by hand, but 85% as good.
1. The Reason they are using the IR-plastic on the trash can is simply design and cost reduction.
2. Maybe D is for dust. ;-)
I wish you would power up, measure and analyze more of the parts until the teardowns. That's why I love the always fascinating video #284 on the electrical toothbrush.
The reflective infrared sensors on the bottom are stair detectors. If the bot tries to go off a stair the sensor goes false and tells the controller there is no floor in that direction, stop, and turn away. Also useful for detecting a pick-up and to stop running.
I have a 500 series iRobot Roomba, it is set up to clean my apartment every Friday, and it does a descent job. Main problem is that it eats the newspaper and/or mail, and 9 times out of 10 I find it stuck under the sofa when I get home.
Hi Dave, infrared couple emitters and sensors on the bottom side prevents vacuum cleaner robot from falling down stairs.
The different IR transmitters seem to be emitting an ID (probably 8 bit, from the trace) and depending on the ID the robot would know if it's to the left or the right of the gap. Similar for the virtual wall beacons.
Somewhere I read about the use of ultrasound in a factory to cause dust to coalesce in the air and drop to the floor. Maybe that's what the ultrasonic transducers where for. That wold be pretty cool.
Dont know if its been mentioned but the pairs of IR leds around the edge are probably proximity detection so it knows if its falling off an edge or something. My Roland keyboard has the same pair for using your hand for effects by moving it closer or further away :)
I always believed these cleaners and the robot lawn mowers made no attempt to track where they had been or were going. Doing that makes little sense. Making unnecessary work and complication. They travel around using random moves. Eventually they will get everywhere. I have one and it just wonders around aimlessly but does a good job in the end.
Couple year old roombas use the same piezo detecting where the dirt gets sucked in, and its lm324 board looks exactly like the ones here. I guessed it just detects a larger dirt amount getting sucked in and slows the vacuum down
You are an engineer Dave. The lights on the bottom are for looks, style points!
The virtual wall thingy can also be used to guide the bot back to the charging station if it's got a large area to work on IIRC.
The lights on the bottom are likely for edge detection. When the device hits a staircase it uses lighting to determine the terrain underneath it. Just a guess, that's more or less how the roombas generally work.
I have an older Neato XV-11 and when it worked it was great. The Neato vacs all use a lidar (angle of return, not time of flight) to actually map as it goes. When it gets low on battery it returns to base using its internal map and then after charging it returns to where it was and continues as if it never left. Unfortunately (or fortunately if you move it around to different levels, e. g. first floor on even days, second floor on odd days) it doesn't remember mapping data between cleaning cycles.
I need to tear mine down to figure out why the lidar isn't spinning so I can put it back into service.
The navigation unit pulse plats remind me of the VOR aviation navigation ground stations. A radial and a timed pulse to define distance.
I have heard horror stories about people who have pets and get one of these... their pet will have an accident and they get home / wake up to dog shit smeared all over a room.
My roomba is really good, it runs daily and the bin always has dust and stuff in it. My home is not dirty but it still cleans a treat.
Agree, we have Roomba (and Scooba) many years, it always collects some dust in rooms which you think are clean.
This is identical to how the cheaper end of roomba works, we had to program them at university to dock and do room mapping.
The down facing IR sensors will be to keep it from driving off stairs and such since it can bump in to void.
The IR sensors on the edge are for fall detection, so robot do not fall of stairs.
I use Ilife A4 - another roomba clone with reasonable quality, which you can get for less than 150$. Cleaning is more fun with robots ;)
Yeah, obvious, never thought of that, as I don't live in a house with steps!
I believe they have different micro because they buy them with the software on them , the go at the Shenzhen market, they find the find the guy who makes what they need (motor driver, sensors manager...) and they glue everything together on the pcb, faster than design it from scratch...
I have no idea why I enjoy these videos I can only comprehend 1% of what you're saying lol
LOL indeed!
That's really mean, it's not his fault he's Australian :(
I think he isn't referring to the accent though. Electrical engineering is pretty much one of the most difficult fields in engineering. But seeing an engineer like him share this much, it's pretty enjoyable imo
as long as Bob's your uncle, it's all good!
You are not alone, so don't worry about it and enjoy the fun.;-)
The piezo transducers on actual Roombas are for listening if dirt is hitting them to go into spot clean mode.
the UV light would be aimed at the dust collected in the device to stop the smell...it would be on all of the time either working or charging but would hav to be quite strong but im sure it would do something over such a long time
I think the sensors on the bottom are to stop it going off the edge of stairs
The piezo are being used to detect dirt, as the brush roll (not in the machine here) spins and throws the dirt into the bin, some will hit those.
Those sensors around the edge are fall protection, same as on the real roombas. Sadly, they are also responsible for the 'dance of death' where the poor roomba after a while gets those sensors dirty, and constantly thinks it's about to fall off a cliff so it just judders around in circles.
The red dust collector part was likely just made from the same mold since it has a similar curve to the front red cover that needed to pass ir. no point having an additional mold.
The infrared sensors at the edge of the robot are distance sensors. They're used for fall-off prevention. The UV light is probably just a gimmick, it's for "disinfecting" the floor.
I wondered if the LEDs mentioned at 5:33 would be for detecting height above the floor. It might be used to determine when it is on carpet vs hardwood floor or tile.
I'm using cheapest and dumbest robo-vacuum for years just replacing the battery pack and the main fan motor every 2 years and I'm pretty satisfied. The fan motor kills bearings very fast because of impeller vibration and dust. My vacuum searches for the docking station by travelling in a random direction until a wall and then follows the wall until the docking station. Perhaps your one also does it, because in the drawing related to the docking station one can see clearance distances along the wall.
The IR detectors around the sides on the front are probably for detecting stairs/dropoffs so it doesn't commit suicide.
I do have one and it works great. not as good as a corded vacuum cleaner but it gets the job done
I wonder why they don't use a laser mouse sensor pointing towards the floor to keep track of movement. Seems like it could be more accurate than wheel encoders. Maybe carpet messes it up?
It seemed to me like they did. The sensors facing down along the edge looked like an optical mouse to me.
Hey Dave, could you add a link/annotation for the led tv backlight?
That little thing is called a "wall" Basically its used to block off areas from being vacuumed. it puts out an invisible barrier that the machine will see and not cross.
Posted this just before the text showed up saying the same thing... ops! lol
@EEVBlog Dave, maybe the piezo devices are impact sensors to determine dust and dirt hitting the piezos creating a voltage. Maybe they found those diameters cheap and needed double the area.
The infrared message says "Come to MaMa".
Please consider getting a name brand one to compare this too! Would be very interesting to see the differences.
One can make very simplified version of such robot pretty easy, for fun: "cardboard robot vacuum cleaner". But iRobot build Roomba-s and Scooba-s very well - durable, good algorithms (random roaring though), they can find the way from under the chair, not stack on cables.
I've had a roomba for a while. Has worked well.
Dave could it be that the halogen lamps are being used to flood the area under the robot with excessive IR light? So as to improve the sensor resolution. This is the only thing that comes to mind as most standard LEDs don't emit enough IR. Also the excessive emissions of light around the robot could aid its base station in tracking it when it approaches the "neighborhood"..
I assume the blind spot down the middle is intentional design. Without it, the robot would be real derpy oscillating back and forth violently as the transmitter was triggering the left and right sensor over and over. With the blind spot in the middle, it lets the robot have some overshoot leeway to appear more smooth without actually doing any real work doing that in code.
The 360 led on the top of the "virtual wall" is there to protect the thing from getting pushed around or knocked over, the Roomba ones have one as well. The ir sensors are there because some homes have stairs and the piezos are to detect dust flow (at least of the Roomba). The Rumba has magnetic encoders for the wheels instead of IR and it also has switches to make sure that the robot is on the floor.
That's indeed a cheap Roomba rip off, the real thing is a lot better but it cleans at random so it takes a long time to clean a room.
the problem with the robot vacuums is two fold, if you have a room or a few connected rooms large enough to make it feasibly useful the vacuum doesn't have enough room for the debris, if you have a room or connected rooms that would fit for the debris you would do a better job taking 10 minutes and a normal vacuum to it. they are a cool idea, the hard floor models are actually decent price to functionality, but generally the tech just isn't there quite yet.
Thanks for the detailed tear down Dave. Sorry about the hair, but I think you will be relieved to know that the hair is not pubes, its hair from a Golden Retriever, that shit gets everywhere!
A roomba, and probably most clones, do not know anything about the room. It just randomly move around, and switch the pattern from time to time. Ex: "move 10ft forward, turn 120 degree, repeat" vs "move in a spiral". After a certain amount of time, it go in base seeking mode: move forward for a certain maximum distance, then turn.. or if it bump into an object it turn and try another direction... Until it find the base IR signal.
The IR led/receiver on the bottom is a stair detector. No return = stair, turn around!!!
The other piece is a virtual fence. Used to prevent the robot from exiting the room. going in a portion of the room that you do not want it to go.
The LEDs around the front are drop off detectors to keep it from going off a ledge or down the stairs
I like your enthusiastic charachter man ,, keep on
I don't like your "charachter", it's spelt wrong.
Dear uncle bob. I sinned today, I called in a hour late at work 'doctors appointment'
In reality choose to watch teardown&mailbag.
thumbs up as always :)
I've had a roomba for almost 9 years now.. they work really well, actually. The only thing I've had to change out has been the battery. Some of those sensors around the edge are probably for drops. Mine will not go within a few inches of a stairway, so haven't witnessed any acrobatics over that time.
That would be ugly.
the ultra violet lamp could be used for it's anti microbial properties although if that is the case I think it's more of a gimmick
that's what I figured.
UV light supposedly kills bacteria. maybe it's like a floor sanitizing thing
I would assume those infrared LED transceivers around the edge are for edge detection so it doesn't take a tumble down stairs or something. It doesn't exactly have ultrasonic sensors for that sort of thing so that's my guess...
Dave, love the video's and have been watching for years on and off but since the kids are getting older I'm trying to get back into my electronics days back in the 80's but have signed up twice for the forum and tells me I need admin approval. Not taking new members? Thanks for the vids!
I've taken apart a Roomba, this looks like it was built by someone who had access to a roomba during their design.
Does this vacuum have a main fan in it? And can you please try to light up the UV lamp?
And those optical sensors on the edge are to signal end of floor so the unit doesn't fall down stairs.
Maybe the transducers are sensing pebble and small debris strikes. They sense tiny impact very well.
I have the Neato XV-11 this is an advanced robotic vacuum cleaner. it uses a 360deg Lidar to map the room. it uses a SLAM and A* algorithms for navigation. P.S. you can take out the lidar and use it for something else. (the serial communication has been reverse engineered )
My nan's got a Karcher one of these and it's the nuts!
The sensors on the side should be for edge detection so it does not fall down stairs.
At 7:33 - Would the ultrasonics be used to somehow keep the dust "less dusty" if you know what I mean? Keep the particles from floating around and escaping, possibly fouling the sensors.
Perhaps that mystery xenon tube type thing is used to generate static to attract dust. Just a wild guess.
I had to subscribe again:( noticed i had no more of your vids on my feed...
I think the purpose of the piezo transducers, 2 of them i mean, is cause when the fan is on the dust has a tendancy to collect on one side or the other. So each one is the same and if ether one senses full it will tell you its full. I hold this reasoning from past mechanic experiance with grass collectors on mowers. They would use 2 sense devices cause the grass would be blown to one side of the compartment more than the other. You don't want your compartment packed so full that it plugs the filters or clogs vacume lines due to lack of air movement.
It's *very* gold!
(Why people feel the need to uglify their stuff with that type of gold....)
Given the closed loop feedback on the drive motors, are you sure they're steppers? I'd expect a normal DC motor.
BTW, I have a roomba, but no, they can't backtrack at all, and I'd be very surprised if this one can. Once its battery is down to "need recharge", it starts looking for the base within its regular random movement program and when it sees it it homes. As you say, it pretty much linefollows in the last bit (you can see it following the wiggly line), presumably using the dead space tactic.
As far as location, I don't think it knows where it is. I'd think when the battery reaches x, it starts keeping an eye out for the charging station.
In more expensive robotic vacuum cleaners this infrared leds under the robot prevents falling down the stairs.
I think you are still giving this more credit than is due to this thing. I really doubt that it is going to somehow register its driven way and just adjust the error with those IR LEDs. From my experience it fully relies on the IR LEDs to find its way back to the base station and otherwise just randomly drives around, trying to cover as much area as possible. All the IR LEDs at the motors and the bottom and mainly there to detect obstacles, steps and if the robot got stuck, and nothing more.
would be awesome to put a jtag serial headers on and see what kind of stuff is running
The inferred sensor is to prevent the robot from falling from stairs. I guess the light is for the inferred sensor??
Hello Dave! I've been making an rc tank and I've come across a problem. The thing is that the remote that I'm making has four buttons(first two buttons are to control the first motor; i.e. to drive the motor forwards and backwards,and the other two buttons do the same thing for the other motor).My problem here is what if you press the forward and backward buttons at the same time? I think I need a circuit that when you press one button the other one will do nothing when you press it. Can you help? I like your videos and keep up the good work :D