I think the original thread "small hub motors" has strayed away from that topic enough to warrant a new thread.
It sounds like you have th>The kiddie car motors have a very long gear train and will
I can't say for sure, but I am wondering if stepper motors are a better choice. They are fairly strong, so they don't need as much of a gear ratio. Sometimes they are even used without gearing at all. The more I think about it the more I am convinced that a stepper is the way to go. You might even get away without using an encoder if you don't expect the stepper to 'slip" much. Wheels are going to slip some anyway, so an encoder is always just a supplement to other navigation systems.
That is pretty big for an indoor wheel. I am sure it helps with transitions, but it also reduces your wheel base. When one wheel is raised while the others are not, it causes the top to sway. This would tend to slosh beverages around. If you switched to 6" dia, then your wheel base could be larger by 3".
That is a great prototype system.
After looking at those serving carts yesterday, I really like them aesthetically. Here is a big wheel one that might serve for inspiration, except that I think it is too long.
I am always surprised at how often I will see someone else's idea, and have doubts about it, only to find that it works in practice. Engineering is surprisingly less predicable of a science than I expected.
Concerning voice control. I have my doubts about that. Even when a large company with a lot of money demonstrates it, there is this time lag from recognition, and the confirmation. A remote control seems to be a LOT more reliable and quick. Even if you have voice recognition, you might want to also include a remote for use when the TV is on, or he is demonstrating it for a group. You might also consider a home automation type of system. These are often used to turn lights on and off, but are also capable of doing a lot more. An interface with the control computer would be possible as well. Here is one source
I am personally favoring the 3-wheeled dragger as you mentioned earlier, with two drive wheels and dragging a caster. With the two drive wheels forward of the center of gravity. I was thinking about the gimbaling myself, but as I looked at existing push serving carts, people seem to somehow manage with them. So perhaps it is not really as much an issue as we are thinking, and would just add unnecessary complexity and weight.
I suspect navigation is the BIG challenge of the design. When Wowwee came out with the Rovio, I thought the challenge of cheap, and easy navigation was solved. I had hoped it was an easily hackable system, but they opted against that. The Northstar system they use was created by Evolution Robotics, but when you visit their site, the Northstar kit is $1,800. Extra projectors (needed for multiple rooms) are $600 !!!
I played around with a Roomba, adding a Bluetooth module and processor connected to a laser and detector. The idea was to spin around and spot reflective targets. I was going to add barcoded reflectors, but never got around to that part of the project. The original article I based it off of is
If you want to know more about the laser-scanner barcode, let me know and I will comment more.
Joe Dunfee