6 ms·

Interestingly enough, for robotic vacuums _low_ weight is also a problem: the better your suction, the worse your ability to drive! The tank-tread wheels on Dy

Interestingly enough, for robotic vacuums _low_ weight is also a problem: the better your suction, the worse your ability to drive! The tank-tread wheels on Dyson's model are meant to help mitigate against this, but I gather from (now ex-) insiders that this is still a buggy sticking point (ha!) that needs to be solved before release.

tgflynn 12y ago
Wouldn't high suction give you better traction (ie. by adding an additional downward force to the force of gravity) and hence mitigate any disadvantage of low weight ? Also with sufficiently well-controlled motors you should be able to optimize suction and drive, say to minimize power consumption or maximize speed/vacuum power.
- kordless 12y ago
  Or better, modulate the suction based on your desire to adjust course. Suck more on the left, less on the right, and heave on the rudder for a hairpin. :)
- jonnydark 12y ago
  It'd give somewhat better traction but at the same time you increase the likelihood of stalling your motors. How does the machine know if the motors are stalling because there's something jammed in the wheels or because the vacuum is sucking stuck to the floor? You can design algorithms or sensor mechanisms to try and determine this and also tune the motors but now you have even more problems!
- arethuza 12y ago
  "Wouldn't high suction give you better traction" Reminds me of the F1 Brabham BT46B "fan car" that sucked itself down to the road using a large engine driven fan at the back of the car: http://en.wikipedia.org/wiki/Brabham_BT46#Brabham_BT46B.C2.A0.E2.80.93_the_.22fan_car.22 http://en.wikipedia.org/wiki/Brabham_BT46#Brabham_BT46B.C2.A...
- IshKebab 12y ago
  The tank treads are sprung, so I think it actually just sucks the sole plate onto the ground rather than the tracks.
darkmighty 12y ago
I'm not sure the ability to drive is that much worse -- for constant curvature surfaces it should just increase traction. I guess the suction could be regulated if a certain varying inclide causes trouble.
- kordless 12y ago
  > varying inclide them bumps
tonylemesmer 12y ago
ex-dyson robotic engineer here. Correct - low weight means you have less force to apply to the wheels and hence achieve grip. The design of the aperture where the air goes into the vaccum (the soleplate) has to be optimised between flicking the carpet fibres in the right fashion to achieve good dirt pickup and not impeding sliding across the carpet too much. The design of the tyres is critical. If there is any slip in the tyres you have a problem. Even though the attitude and trajectory of the robot is governed by the information coming from the camera it does also rely on feedback from the wheel speed sensors. If you have slip on one side and not the other then you will tend to spin around and not drive in a straight line. Adding more power to the slipping wheel merely exacerbates the problem. You'll notice the treads on the tank tracks are chunky. This is to give maximum grip on thicker pile carpets, however this kind of carpet tend to be "squishy" and allow the wheels to float somewhat on the carpet surface no matter what design of tyre. So this is probably where they are having problems. Also you'll notice the wheels are not rigidly mounted to the robot chassis, they have suspension. But unlike car suspension the bottom of the robot does take some of the weight and it touches the floor. If you have more mass in the robot it gives you more latitude to distribute it between the wheels and the soleplate. Its a careful balancing act and all of these variables have to be tuned based on the amount of suction your vacuum motor is providing.
- rbobby 12y ago
  Add suction to the treads? A few air holes routed to the side of the tread where there's a vacuum pickup? I bet it would be tricky to get a seal that has low enough friction to allow the tread to slide past but still a good enough seal to get good suction from the bottom of the tread. Oh and it's got to last and last. Yikes... back to coding I go...
  - imdsm 12y ago
    I have great ideas, which are actually terrible ideas, that's why I stick to coding.
- Shivetya 12y ago
  can you not get any propulsion from a beater bar?

tgflynn 12y ago

Wouldn't high suction give you better traction (ie. by adding an additional downward force to the force of gravity) and hence mitigate any disadvantage of low weight ? Also with sufficiently well-controlled motors you should be able to optimize suction and drive, say to minimize power consumption or maximize speed/vacuum power.

kordless 12y ago
Or better, modulate the suction based on your desire to adjust course. Suck more on the left, less on the right, and heave on the rudder for a hairpin. :)
jonnydark 12y ago
It'd give somewhat better traction but at the same time you increase the likelihood of stalling your motors. How does the machine know if the motors are stalling because there's something jammed in the wheels or because the vacuum is sucking stuck to the floor? You can design algorithms or sensor mechanisms to try and determine this and also tune the motors but now you have even more problems!
arethuza 12y ago
"Wouldn't high suction give you better traction" Reminds me of the F1 Brabham BT46B "fan car" that sucked itself down to the road using a large engine driven fan at the back of the car: http://en.wikipedia.org/wiki/Brabham_BT46#Brabham_BT46B.C2.A0.E2.80.93_the_.22fan_car.22 http://en.wikipedia.org/wiki/Brabham_BT46#Brabham_BT46B.C2.A...
IshKebab 12y ago
The tank treads are sprung, so I think it actually just sucks the sole plate onto the ground rather than the tracks.

darkmighty 12y ago

I'm not sure the ability to drive is that much worse -- for constant curvature surfaces it should just increase traction. I guess the suction could be regulated if a certain varying inclide causes trouble.

kordless 12y ago
> varying inclide them bumps

tonylemesmer 12y ago

ex-dyson robotic engineer here. Correct - low weight means you have less force to apply to the wheels and hence achieve grip. The design of the aperture where the air goes into the vaccum (the soleplate) has to be optimised between flicking the carpet fibres in the right fashion to achieve good dirt pickup and not impeding sliding across the carpet too much. The design of the tyres is critical. If there is any slip in the tyres you have a problem. Even though the attitude and trajectory of the robot is governed by the information coming from the camera it does also rely on feedback from the wheel speed sensors. If you have slip on one side and not the other then you will tend to spin around and not drive in a straight line. Adding more power to the slipping wheel merely exacerbates the problem. You'll notice the treads on the tank tracks are chunky. This is to give maximum grip on thicker pile carpets, however this kind of carpet tend to be "squishy" and allow the wheels to float somewhat on the carpet surface no matter what design of tyre. So this is probably where they are having problems. Also you'll notice the wheels are not rigidly mounted to the robot chassis, they have suspension. But unlike car suspension the bottom of the robot does take some of the weight and it touches the floor. If you have more mass in the robot it gives you more latitude to distribute it between the wheels and the soleplate. Its a careful balancing act and all of these variables have to be tuned based on the amount of suction your vacuum motor is providing.

rbobby 12y ago
Add suction to the treads? A few air holes routed to the side of the tread where there's a vacuum pickup? I bet it would be tricky to get a seal that has low enough friction to allow the tread to slide past but still a good enough seal to get good suction from the bottom of the tread. Oh and it's got to last and last. Yikes... back to coding I go...
- imdsm 12y ago
  I have great ideas, which are actually terrible ideas, that's why I stick to coding.
Shivetya 12y ago
can you not get any propulsion from a beater bar?