If Tesla wants to show off advanced summon, it could start at their superchargers

Even when slots are empty, you still must move.

Elon Musk has bragged that soon the "Summon" mode in Teslas will let you summon the car from across the country. They are a very long way from that, but there is a summoning application which they could implement which would actually be useful and solve a problem electric cars have, namely the sharing of charging stations -- particularly the supercharger.

Valet parking was one of the earliest robocar demonstrations. I first proposed it 10 years ago and Stanford and Audi did demos. It was actually the very first Cruise business plan. Except for the issue of pedestrians in the lot, it's one of the easiest problems to solve, and it can be done with just cameras because it's all low speed.

With low speed chargers, the problem is cars park there for hours, sometimes all day, and stay there after they are full. Some charging stations toss on a low charge like $2/hour to hog the station, but if you parked some distance from your destination, that's not much of a solution.

With the superchargers, there are two problems. Sometimes the superchargers are all full, and people sit in their car waiting. Once the supercharging is done, Tesla charges you a large fee to hog the station, unless you come get your car within 5 minutes.

The cars should be able to park in charging spots, and leave them for regular spots, but they can't plug themselves in or remove the plug. The answer is to get the arrivals and departures to be the plug jockeys, by not letting them charge unless they have done a quick round plugging and unplugging the cars that need it. Frankly, most people would probably do that as a courtesy anyway, if asked.

Here's how it could work.

  1. When you arrive at the charging lot, take an empty space, or if there are none, park in a marked regular "waiting" space near the chargers. The system might allocate a space for you, even reserve you one. If somebody is in the space, just tell it and you'll get assigned another.
  2. The screen of your car, and the app in your phone, will present you with the list of cars that need plugging or unplugging. In addition, LEDs on the charging stations could in future indicate this status. Walk around the lot attending to the cars, and of course plug in your car if you got a free charging station.
  3. All cars in the lot are scanning the lot for pedestrians and other cars. They indicate to the Tesla server when the lot is clear, and the Tesla server tells the cars that need to move that this is true, one at a time.
  4. If a car is waiting for spot, and one is finished and unplugged, they switch places. (One car would drive just past the other, then wait for it to pull out, and back in.)
  5. Otherwise, as needed, cars move to free spots when available, and out of spots to waiting spots once unplugged.
  6. When a human arrives to pick up their car, they must do a quick run, as specified on their app and car screen, to plug and unplug cars. If they don't, they are not blocked from leaving but they pay a penalty.

As designed, the cars never move on their own if there is another car or pedestrian in the charging area. This presents a problem if somebody enters the area during car movement. The cars could be flashing a special light pattern to indicate they are in valet movement mode which people would come to learn. Or they could stop dead if a pedestrian arrives. Ideally the lots would have sidewalks to let people get to the charging stalls without walking in the driving area.

This approach designates a set of regular parking stalls as waiting zones. In some lots that's easy, in others it's harder, or might be some distance from the charging area. To handle the latter, the cars would need to be rated for safe movement with pedestrians. The first version of this is designed to be done with just a software upgrade. Other functions, like alternate lot design and lights on the stations to indicate who needs plug service, can come later.

Non-electric drivers might block the waiting spots, of course, even though they would be marked as for waiting electric cars only. They sometimes even "ICE" block the charging stations. The system can spot that and send enforcement -- even send pictures of licence plates. However, if that happens, the owners can be signalled on their phones to come and resolve the problem.

Instead of waiting spots there could be a waiting "line," if there is a place to put it. In fact, today that's what happens at very busy chargers, people wait in a line for the next one. So pull your car to the back of the line, do your plug duty, and while you are gone, the line will advance and your car will get to the front, and then take a spot and wait for somebody else to plug it in. Since every arrival and departure gets plug duty, that should happen fast. If it doesn't, you'll get notified.

This would allow more efficient use of the chargers, and allow people visiting them to take longer breaks for shopping or dining without having to worry about the charge cycle on their car.

This approach could also be used with regular level 2 chargers, particularly if those can be placed in a way so that they can reach 4 different cars. I outlined a less involved system without self-driving in this article.

This also opens up better shopping options. For example, a popular supercharger is in Folsom, CA, and everybody going to South Lake Tahoe needs to use it. I like to shop at the Costco near it (there is no Costco at the lake) but the Costco is about a kilometer walk away, which is not practical, and you certainly can't rush out from shopping to move your car. This could solve that. (Or I could switch to Sam's Club, I guess.)

Because the cars will handle backing into the charging spots, it makes it easier to design the lot. (Drivers prefer the stations which have the supercharger on an island which allow you to enter the station forwards rather than backwards.)

You could elect to wait in your car and sit in it while it moves itself to the charging station. You could then plug it in yourself for fastest use. Otherwise it waits for somebody to arrive or leave, or for you to get the signal and come to do the plugging.

It is possible that your car might need to plug in but nobody comes or goes for a long time, delaying your start of charging. This should be very rare since we're talking about an overloaded charging lot. Your phone can alert you, giving you the choice of returning to your car to plug it in. You're not much worse off than if you had to sit in line. However, since many people drive to charging stations by entering them as a navigation destination, a company like Tesla could make note of that and predict when people will arrive. It could even insist you use navigation if you want to be in the queue when you arrive. This would allow the system to warn owners if nobody will be around when their car needs plug service.

Even when there is no line

This functionality is still useful at more lightly used stations which don't get full up. Tesla currently charges a fee if you don't quickly move your car if more than half the stations are in use. The ability of the car to remove itself, once unplugged, would eliminate the need for this fee, or for people to worry about getting back in time to move their vehicle.

Simple version

A simpler version of this would work only in lots where there is another parking space opposite the charging space. Many lots work this way. Once your car was unplugged, if the opposite space was empty, it would then slowly move into it. Somebody else could take the charging space. Once that one was full, if you're still there, you would be told to move your car, unless that owner is there and leaving. This would probably give you a 20-30 minute buffer after your car charges before you have to get back. The driving would be very simple, almost like existing summon, except it must make sure no people or cars are in the short path to the space.

It could also go the other way -- wait in the opposite space. Tesla's network will know how long each car has left on its charge, and who has a free opposite space, and tell you which to take.


If a vehicle is capable of driving itself to a designated charging spot, it should be capable of directly docking with the charging station. If Roomba can do it, why not Tesla? Is this on anyone's radar?

That would require a significant hardware change in all cars, and also additional cost as each car would need to have the old connector as well as the docking approach. To make the switch, you would either want:

  • The docking hardware to be super cheap so there is no big burden to add it to the car
  • Lots of dock charging stations so it's worth having that
  • A car that can drive the regular streets to go find charging on its own, which thus no longer needs the original connector.

Tesla uses its own connector, which is superior to the two standard connectors (SAE Combo/J1722 and Chademo.) However, they have a small adapter to let Teslas charge from SAE1722 which is the most common standard connector. One superior aspect of the Tesla connector is it has a data protocol so that billing for charging is communicated over the connector.

I have proposed a very simple system, where you just have a box on the ground that the car drives over, and retractable pins which either come up from the box or down from the car (the former is probably better but requires two retractable covers instead of one.) This is because the car is a robot and can position itself precisely so you don't need much mechanism. You could also have a robot insert a physical connector on the side into a car that positions itself perfectly, but that's much fancier than a box on the ground you drive over. However, it means using the same connector.

But the plan I outline above is a software change -- no hardware change needed.

If Tesla did what you are proposing, wouldn't it fall under the definition of a level 4 robocar? The operating domain would be extremely narrow, but within that domain they are operating completely driverlessly.

I don't subscribe to the levels -- they are misleading and hurt people -- but if you do subscribe to them you could say that.

However, on private property the rules are completely different from public roads. Fully autonomous vehicles have been for sale for use on private property for quite some time. In theory all the levels only apply to public roads.

Are the rules really different in a parking lot that's open to the public?

If so, maybe they should enable a real summon mode in such parking lots. https://www.youtube.com/watch?v=uMM0lRfX6YI

Driverless in parking lots at very low speeds seems like something they can do in the short term (as you say it can be done with just cameras, and they also have ultrasonic sensors), and the work in designing the software to do it is largely what they're working on with summon anyway.

But in the states whose driving laws I'm familiar with, the driving laws cover all roads open to the public, whether they are rights of way or privately owned. Is suppose they might be able to get around that by closing their charging stations to the public, but I'm not sure exactly how they'd go about doing that.

Seems like regulatory issues are going to be the blocking factor, and once they're resolved there's no point in not making things truly automated.

That's not the case in California. Which states apply their vehicle code on private land? Of course you are still liable for torts on private land -- if you hit somebody, you still have to pay for it. Most other regulations do not apply.

All states I know of apply at least some parts of the vehicle code on some types of private land. It's hard to generalize beyond that without knowing which law is of concern and which type of land.

I've tried to figure out what California does and so far have failed. Do you have a statute or case saying that the California vehicle code doesn't apply to parking lots that are privately owned but open to the public? I searched a bit and can't find it.

I just found various web sites saying it doesn't. And unless it says it does apply, it would not. I thought most vehicle codes say they apply only on "highways" (which means any kind of road and even includes the sidewalk.)

I had always been told long ago that while they put stop signs in parking lots and it is wise to obey them, they don't have legal force, if you do a rolling stop etc. Again, you can still be liable for any tort, including probably hitting somebody because you didn't stop at all.

You're right in most states regarding stop signs. This usually comes down to the fact that the stop signs themselves don't fall under the definition of a "traffic control device," though. It's not that private property is exempt, it's that stop signs put up by Joe Schmoe generally lack the force of law. State laws apply everywhere in the state unless they are restricted to certain locations, such as "highways."

Nonetheless, I'd urge caution about what you read on "various web sites" and what you've "always been told long ago."

So please cite for me the section of the California Vehicle Code, or other major state codes, which say that the code, in general, applies on private property. I am also interested in cites where it says specific rules from the vehicle code apply on private property. I am sure there are some, but in reading the analysis of others they report it is not that common. Prove them wrong!

First cite for me the section of any state's code that says that murder laws apply on private property.

If the code doesn't say something one way or the other, I would suggest looking at the case law to see how the courts have interpreted the lack of explicit guidance.

But many vehicle code rules say they apply to the highways, unlike the murder laws. But not all of them, I agree.

The main laws that apply to robocars at first blush are not the vehicle codes but things like the FMVSS which don't apply to fleet vehicles on private roads (and may not apply to fleet vehicles that are never sold at all.) You need a law by law analysis but generally in most states it has shown that operating a robot on private land is OK where it might not be on the roads. Hitting somebody on private land is illegal.

I'm not sure what FMVSS has to say about selling a car that can operate without a driver, but only on private roads, but that's also something important if Tesla wanted to sell cars that could do advanced summons on private roads. These aren't private fleet cars that we're talking about.

There have been a lot of parking lot valet systems built for demos, planned for sale even. Though none are currently for sale. I have not done the personal analysis but I presume they have and concluded they could sell such. Existing Tesla summon does require the "driver" be present (though outside the vehicle) so it could be treated differently.

In the ideal scenario there are always enough chargers so that no one has to wait? What is the scarce resource that prevents this from happening?Is it space, amperage, or electrical cabling?
I am going to make the assumption that superchargers are mainly used when making long trips, as for regular charging the vast majority will be done at home.
In such a scenario the best location for superchargers is where major routes enter cities, and strategic locations in the country. In this scenario amperage is the likely limiting factor.
If that were the case, you could have more charging spaces, all connected, but only a limited amount actually charging at one time.
Only very simple software is then required to queue the cars fairly.
I admit U would need to do actual sums to be convincing, not having looked up the cost of cabling, and that usage patterns for charging stations.

I think all things cost money -- stations, land and available power. But I think stations and land are more expensive, they they are not limited in most cases by the megawatts. Superchargers tend to locate in retail centers because people pausing wish to eat, shop, pee and do other things during their charge period.

Right now, your intuition turns out to be wrong -- the busy superchargers are the urban ones. This is because of some combination of Tesla giving out free supercharging, causing people to use it just to save the $4 to $8 the electricity would cost at home, and use by people who don't (yet) have level 2 at home -- including many people in their first month of ownership, and all those who don't have a personal parking space they can install charging at.

Finally, Tesla has given free supercharging to so many that they don't earn money directly from most of those charging, so there is no incentive for them to spend a lot of cash to fix the shortage. If the customer is paying I would guess the station brings in $15/hour -- but has costs almost as much as that. Tesla has declared they will run superchargers "at cost."

So the problem addressed by my plan is twofold:

  • If the station is full, you must wait in line
  • You must come get your car and move it as soon as it is full. (Or rather, as full as you want it to be.)

In particular, a typical plan for the supercharge is to go have a meal or shop. But if your supercharge is going to be modest (20-30 minutes) that's a fairly rushed meal or even a rushed shopping trip. So it would be very nice to not worry, to just come out and drive away when you are done. If the car can move out of the stall into an open space, you can do that.

The other goal is to make something with zero hardware cost, since that would greatly impede deployment.

Of course, the cost of this software is not zero. But Tesla wants to build this level of capability into the cars already, they keep promising it. This is a simple project with immediate benefit for owners in a controlled environment.

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