Skid Steer Tadpole Trike
- Thread starter gromike
- Start date
Yes, that's the part i was really referencing, but didn't have time/brain to get and make the quote. :/
gromike
10 kW
Well, that's where this whole thread is going!
Maybe by building this cargo sledge I'll learn how to build the best EPMAD in town.
Race you to the Senior Center!
FWIW, I recommend against caster wheels at all, for anything other than slower-than-walking-speed stuff.
I used them to hold up the front end of one of my dog/cargo trailers while riding, and had nothing but problems--the wheels would shimmy if in front, and the trailer would "slide" all over the road if in the rear. Didn't matter if they were single or paired. Problems never went away until I built one that used only the main non-caster wheels. Some of the experiments on that are in my early Trailer threads here on ES (some of the rest might still be up on my old Electricle blog from before I found this forum, but some stuff is missing there nowadays).
If you want to see what something will do with casters on it, used in various ways, just go to the store and play with the shopping carts in the parking lot.
If you can get the control algorithms right, you could probably make it work at higher speeds with computer-controlled powered-steering of those wheels, but they wouldn't be casters at that point. It would also probably not be easy, since you require sensors to detect everything from road speed overall to all individual wheel speeds (so you can track which way the whole thing is going vs the road itself, by tracking all that over time), and using these to point the wheels being used for steering in the right way to keep it going straight despite road surface problems (holes, bumps, pitches, crowns, gutters, etc). Then you need sensors on your own steering input device (tiller, handlebar, etc) that can be used to offset the steering control in the right way to make it go the direction you want by *only* the amount you want, and autocorrect the steering output to prevent oversteer by monitoring all those other sensor inputs. The design would probably get fairly complex fairly quickly.
If you skip casters entirely, and only use normal main wheels to do the steering, even if they are fixed in place and can't pivot, so you're doing tank-style steering, then you can control just the wheel speed (or individual wheel torque vs overall road speed) to steer it, and that should be much simpler, especially if it is only the front wheels that do the steering, and any rear power (if present) is a "passive" differential, either mechanical (middrive thru phsyical diff) or electronic (such as via hubmotors in torque control).
I used them to hold up the front end of one of my dog/cargo trailers while riding, and had nothing but problems--the wheels would shimmy if in front, and the trailer would "slide" all over the road if in the rear. Didn't matter if they were single or paired. Problems never went away until I built one that used only the main non-caster wheels. Some of the experiments on that are in my early Trailer threads here on ES (some of the rest might still be up on my old Electricle blog from before I found this forum, but some stuff is missing there nowadays).
If you want to see what something will do with casters on it, used in various ways, just go to the store and play with the shopping carts in the parking lot.
If you can get the control algorithms right, you could probably make it work at higher speeds with computer-controlled powered-steering of those wheels, but they wouldn't be casters at that point.
It would also probably not be easy, since you require sensors to detect everything from road speed overall to all individual wheel speeds (so you can track which way the whole thing is going vs the road itself, by tracking all that over time), and using these to point the wheels being used for steering in the right way to keep it going straight despite road surface problems (holes, bumps, pitches, crowns, gutters, etc). Then you need sensors on your own steering input device (tiller, handlebar, etc) that can be used to offset the steering control in the right way to make it go the direction you want by *only* the amount you want, and autocorrect the steering output to prevent oversteer by monitoring all those other sensor inputs. The design would probably get fairly complex fairly quickly.If you skip casters entirely, and only use normal main wheels to do the steering, even if they are fixed in place and can't pivot, so you're doing tank-style steering, then you can control just the wheel speed (or individual wheel torque vs overall road speed) to steer it, and that should be much simpler, especially if it is only the front wheels that do the steering, and any rear power (if present) is a "passive" differential, either mechanical (middrive thru phsyical diff) or electronic (such as via hubmotors in torque control).
gromike
10 kW
Maybe a caster wheel that can be pinned to center, and unpinned for low speed maneuvering?