‘net-neutral load’ electric powered trailer

I am fairly sure it would be easier to use a standard throttle with a long wire. . .but:

I have just been reading about this new type of electrically assisted bike trailer, it looks fairly standard apart from the throttle being replaced by a sensor that pushes and pulls, and adjusts speed accordingly.



http://www.rippl.bike/en/rippl-41-low-impact-city-logistics/#more-30

My question is: "What components make that switch work?"

Could you create a switch like this that would connect to a standard controller? The trailer appears to use regen braking to slow down, so that could be an option in the design?

I have read the strings on "push trailers" and also powered trailers, but is this a new idea, and if so how do we think it might work.

Also video in action. It looks like there is some sort of cable hook up . . .

[youtube]https://youtu.be/06TFgXvB9bk[/youtube]

I would expect just like a PAS "torque" sensor. The only difference is that it's supposed to respond to force in both directions (if configured for a direct drive motor, which would have that regen braking option.) From a design point of view, I guess that would mean a fairly wide range of values around the equilibrium coasting state, so that the controller can reliably detect the difference and not be pulling in the wrong direction accidentally because of some miscalibration. More of an "S shaped" input curve, than flat.

A trailer when loaded can be heavier than the riding weight of the bike it’s hooked on, especially if it is motorized and has some battery capacity. In that situation, I would definitely prefer the power on the bike instead. I don’t like the idea of being hooked to a trailer heavier and more powerful than I.

We're getting there, but nothing yet quite responds as quickly and as smart, as your hand on a throttle. I could see that thing getting an oscillation going, and buck the crap out of you. On off, on off, on off, whee! Maybe it works with a dead man switch you can just let go of when you want.

Besides, towing heavy trailers there is only two things you ever want, Throttle full on, and throttle full off. A doorbell button for a throttle would work fine.


Partly, this is just a desire for bike riders to make a flyweight motorcyle ride like a bike. Us motorcycle riders couldn't care less about that. We just like a good throtle. It is possible for a bike rider to learn to use a throttle, but he hates it, and his flyweight motorcycle will never ride like his bike did. Its a motorcycle/moped now.


Bear in mind though, having it work well is far from the first priority. Having it sell to bike riders is the only important thing.

I'd think some sort of load cell to detect, well, the load on the hitch would be required. Similar to how a torque sensor works but linear instead of rotary, but as Dogman said, you'd need the response to be very quick to avoid it creating a feedback loop causing ever increasing oscillation in the power.

Really you'd need to program a microcontroller or something to filter out the inputs and discern between those oscillations (which are to some extent inevitable just by the nature of the system) and actual load variations. No simple switch is going to do what you want.

You'd also want a motor controller that uses a current/torque mode throttle input, a speed based one would be difficult or impossible to modulate well enough to avoid oscillation.

There's been some discussion here and there about how this might be done in some of my trailer threads (possibly in the SB Cruiser and CrazyBike2 threads as well), though I don't have a direct link. I recommend checking the Mk IV trailer thread first to see if it's in there, then the posts with "trailer" in them in the SBC thread (there's a lot, so you'll need to skim a fair bit).

Similarly, surge brake systems ahve also been discussed in the trailer threads (mk IV, I think, mostly), and the same kind of system could be used to control the power application as well as braking.

Any of the systems would require tuning for the conditions and load, most likely.

Because I haul such heavy loads when I do use a trailer (hundreds of pounds), I intend to eventually have the trailer have it's own power in addtion to that on the trike, and no electrical connections between them, so the trailer will have to respond to pull and push on the tongue in a similar way to surge brakes on automotive trailers, in an analogue way, rather than an on/off way.

Because of the loads I carry, I presently use automotive ball hitches, and large tongues. Biggest loads carried so far are a piano, and a few hundred pounds of dog food.