So here we are proof of concept build #2. No more sliding rig, instead it's a pivoting pendulum structure from a frame that will also support the solar roof. We finished this on Saturday afternoon, went for a spin, did more tweaking, and in a nutshell, excellent
We got some footage for another video blog update that we'll get ready soon.
But what we didn't get was an evening trip that Me and Anne-Sophie took riding/rowing through a popular strip in Vancouver. The response from people on the street seeing a vehicle like this is just electric. From the backwards facing rowing rig you get to see everyone's faces, comments, waves, cheers, camera shots etc. as you pass by. I'm used to some of that riding a unicycle
, more so on the Penny Farthing
, but this was in a totally different league, and facing backwards you get to see and interact with it.
teklektik wrote: ↑
May 06, 2018 10:41 am
I'm kind of curious about the pulsing assistance sensation for the captain when the stoker (stroker?) applies power strokes... This almost seems like it would tend to move the captain in and out of the easy cadence for the selected gear which might detract from the efficiency of his contribution. This a different situation than two pedallers or two synchronized rowers where the load is more constant or well-behaved.
This seems one of those 'gotta try it' questions and I'm wondering if you've been able to make a long enough test ride to get a sense of this.
Very spot on observation. I haven't yet ridden on the front to experience this, but Anne-Sophie sure mentioned it on our Saturday evening promenade. On the slower uphill portions it was prominent, much less so on the flats and downhill even though I was rowing just as hard.
That's probably because a given amount of energy corresponds to a much lower change in velocity at high speeds than lower speeds, given the E=1/2mV^2 relationship. I estimate rowing modestly that each pull stroke is 300 joules. Ballpark total vehicle weight is 200 kg. Here's the change in speed we'd expect from a 300 joule energy impulse:
Code: Select all
Initial Speed Delta Speed from 300J
5 kph + 3.0 kph
10 kph + 1.8 kph
15 kph + 1.2 kph
20 kph + 0.95 kph
30 kph + 0.64 kph
40 kph + 0.48 kph
Now that's if all the energy went in as a single impulse and then nothing for 2 seconds. Since it's spread out over a 50% duty cycle, it would be to first order about half this much for the velocity change. Still quite noticeable for the captain at low speeds. But once we have the electric motors on and are generally cruising >20 kph then my expectation is that that this will be imperceptible.
If not, then I'd likely explore using a constant speed feedback loop on the CA3 and use the motor to dynamically smooth this out, exactly as demonstrated in this post: