I'm not sure that these intuitions are actually correct. For example, while it seems obvious that a four wheel solution should be faster and cheaper, that is only really true if you assume that software and controls algorithms are expensive. This robot needs fewer wheels, tires, frame structure, and drive motors than a conventional four wheel design, and the ability to lean into the direction of motion gives higher acceleration limits, increasing speed. Just like a bike is cheaper and higher performance than a recumbent tricycle, this might actually be cheaper and higher performance than something more conventional. If not today, Boston Dynamics seems to be betting that it will become so in the future.

The counterweight swinging seems like a major hazard. Also, I am curious what stability issues it will have if there is a sudden hazard appearing (let's say person walk in front of it).

Judging by the video, the swinging weight is used to provide all sorts of acceleration: forwards, back, and to lift the payload.

This is a smart usage of a dead weight (batteries) that makes all the other motors smaller and lighter.

Cover it with a hard plastic skirt at the max range of motion.

>The counterweight swinging seems like a major hazard.

Seems like an easily enough problem. Basically every car out there has reverse sensors...

You are assuming that there are people around to be a liability. I am assuming there will be no people in this warehouse.

The people will always be there to restart the system and clean up the accidents. Robots have to be designed in that in mind.

Restarting systems and cleaning up seem like jobs that can be/have been automated.

Nitpick: recumbents are faster.

Interesting. I just looked more into this, and it seems to depend on what performance regime we are measuring speed in. It seems like recumbants are always heavier, which makes them worse on hills, but extremely optimized recumbants with aerodynamic shells are lower drag on flat ground. From an agility perspective, uprights always win, which is probably the closer analogy for "cycle speed" that Handle cares about.

Thanks for teaching me something :)

Basically right, except for one detail: Heavier recumbent bikes are slower to get up hills, due to being heavier. But that extra weight actually makes them faster going downhill. Not enough to be faster overall if the power source is still one person pedaling, but still.

Source - I was part of a project in college that built a recumbent tandem bike. We built the frame out of large-diameter steel tubing, and it was quite heavy. I followed it on a normal bicycle several times while testing. Even with 2 people pedaling, it was easy to keep up with going up hills. It would tend to get away from me going downhill though.

The main difference is that on an upright bike one cannot exert more force on the pedals that the body weight, while on a recumbent the upper body is locked into the chair and pushes against the back.

Not true. It's a completely standard technique to pull down on the handlebars to exert more force than your body weight on the pedals. Watch any video of a pro cyclist climbing hills, or sprinting on a straight.

This was my reaction too, but after I thought about it for a second it seems only half right.

For a device leaning into shelves to grab things, being dynamically balanced might be useful. Like a racing sailboat with a movable keel or ballast. But you could do that with a three wheeled design.

I bet there's also a static version of this bot with three wheels, slightly larger footprint, where the battery pack is situated over the third wheel for leverage.

But the swinging battery pack? In theory it reduces the footprint of the bot, but any time the bot is trying to grab a package, the battery is moving. Which means you can't let another robot or human enter that space. So either you have a very very complicated calculation of what areas of the warehouse are 'empty' at any moment, or your logistics program has to treat the robot like it's its worst-case footprint at all times. At which point you might as well make it static. Right?

Is this physical safety margin a substantially different problem than human-operated machinery, though? You don't want to get too close to a live forklift, either.

Seems like it wouldn't be too hard to just put a cover over the batteries entire range of motion.

OSHA would want a light curtain like on virtually every other machine in a factory

> Two wheeled dynamically balanced warehouse robot like that is completely unnecessary complication.

I had the same intuition, but then I remembered the toy I'm playing with - the spectacularly unstable 4-rotor copter that could not even take off without an onboard computer actively keeping it level all the freaking time. And it's rock solid almost no matter what.

As technology changes, our intuitions must follow.

4-copter has use for the balancing and has replaced complex mechanical flybar with cheaper electronics.

2-wheeler is not better or more stable than 4-wheeler and requires more maintenance.

And 4 wheeler will be cheaper.

Are you 100% sure? 4 wheeler needs twice as many wheels and a larger frame. A little controller and imu is pretty cheap by comparison.

You need to consider also possible issues and maintenance.

Wheel issues (typical):

1) flat tire (if the wheel is not "solid" only)

2) axle bearing

Controller+swinging counterweight:

1) a gazillion electronic components, connectors and contacts, bearings as well, the actuator for the swinging, etc., etc.

What happens if the environment is a bit humid?

For the wheel, a little rust, for the complex electronic system?

And BTW, we can save 25% by using only three wheels ...

Not just a little controller, a counterbalancing mechanism with gyroscopes, etc. Versus a motorised trolley.

> a counterbalancing mechanism

if the 4-wheeled version must also have the same level of acceleration and speed of picking up, won't it also need a counterbalancing mechanism? It just won't need the "balancing algorithm", but will need a way to balance the arm swinging out.

Also, the counterbalancing mechanism is written with software, so once perfected, it's "free" to deploy. The weight could be the actual batteries, so no added extra weight!

A car accelerates way faster.

Do you see cars with huge counterweights?

And no, it is not free to deploy by any means. Any moving, huge, swinging parts will cause expensive problems. Remember your hard disks.

A car does not have an arm that picks up heavy objects. The ones that do (crane trucks) need outriggers and jacks to stabilise the machine and stop any motion before they can extend their arm.

Fork lifts (no outriggers), optionally with a crane arm/jib, are normally used to move goods inside warehouses.

Of course it depends on the weight of what you are moving, but it doesn't seem like the 2 wheeled robots in the video can actually move "heavy" weights.

These robots go only up to 15 Kg according to their designers.

I would not call 15 Kg "heavy". I can carry that myself on a single arm...

What do you mean a counterbalancing mechanism? Multiple gyroscopes? It's just a cheap IMU (includes gyrometer) and an additional control output in their controller.

Cheaper and will not automatically fall over in the case of a power failure.

Or a bug! I assume it will also consume less power.

I think it is like LHC, core concept may be waste of resources for some however the benefit here is research and development on materials, sensors, engines, power supply, automation so on. At least better than arms race (I know that DARPA funds some robots).

> I know that DARPA funds some robots

DARPA funding is not necessarily violent. One can argue that the current explosion in self-driving cars is due to the DARPA challenges in the 2000s.

DARPA's mission is "to make pivotal investments in breakthrough technologies for national security". Depending on how you view national security, you can make some easy arguments for DARPA investing money into sectors that help increase the nation's economy.

Maybe an obsolete objection. "Just use coal for god's sake. All these electronics - bah!"

I think they have solved 2-wheel control. Lets move on.

They may be working around Deka patents.