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I have temporary mobility problems where I can't walk for days. I am inspired by the Kiva robotic distribution system to make a device to transport me around the house, (or perhaps two or more units to pick up my bed and move it).

Basically I want a stool that I can sit on that can spin on the spot and drive in different directions over slightly bumpy flooring - maybe 1 cm level shifts. I will use manual control. Fancy Segway style stuff can come later.

I've looked at different technology including electric wheelchairs (which are far too large and cumbersome and expensive). I've also looked at electric skateboards including adaptations of RC aircraft motors - not for actual transport but for design ideas.

My requirements are two motors, one per road wheel, that have effective torque over the speed ranges required (0 - 1.5 m/s) and that are reversible. They will drive ~ 200mm road wheels via a reduction system and have proportional control.

The questions are what motor technology? And what controller technology? And what battery technology? Cost is an issue so perhaps hobby-grade systems might be the best choice?

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  • \$\begingroup\$ The key design criterion is going to be "how much power do the motors need" and "what torque/reduction ratio must be available at the output of the gearbox". Looking at 'hoverboards' and electric scooters, I suspect you're going to need 50-100W and a budget of $200 for new components. Might be able to keep the cost down by repurposing electric screwdriver or car wiper motors. \$\endgroup\$
    – pjc50
    Sep 11 '16 at 10:31
  • \$\begingroup\$ Also relevant : what are you willing to do to the house to support this system? That's a precision laid epoxy sealed concrete floor with no tiles, door sills or carpets, to give the robotics an easier time. (And guidance systems laid in the floor). Those electric wheelchairs are so clumsy mainly because they have to be mobile and stable on inferior surfaces. \$\endgroup\$ Sep 11 '16 at 12:48
  • \$\begingroup\$ Single motor with steering MAY be cheaper. To play - old electric drills may have enough power. DC brushed is more available surplus. DC brushless good but tends to be high speed so needs very high gearing. Wiper motor can be good but bearings etc not rated for super long life. Can get truck wiper units with more power. \$\endgroup\$
    – Russell McMahon
    Sep 12 '16 at 0:28
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If this is something you want to build fast, and get it working, then KISS is the only way to go, Keep It Simple StupidSoYouDontHaveLongDevelopmentTime.

Battery - SLA sealed lead acid - tame, easy to charge
Motors - DC peramanent magnet - tame, easy to control
Controllers - buy something like 4QD (other makes are available) - don't design and build H bridges from scratch
Wheels/Gears - buy a 'motor with a reduction gearbox to a wheelchair wheel' in one assembly, rather than start bolting and milling and mounting

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