Today, you're proposing marriage. And your plan is awesome: You'll send your true love on a walking tour of the city, past every romantically significant waypoint. The park bench next to the pond. The fish market. The statue in the traffic circle. Your favorite cafe. (With a detour through that special alley, you scoundrel). At the end, your beloved will arrive at the rose garden to find you, beaming, with ring in hand. The light of your life won't need a map, or a trail of convoluted clues, either. Instead, you'll control your moon and stars via leg-mounted electrodes.

Ah, modern love. Or at least a glimpse of it, brought to you by German scientists who have developed something they call cruise control for pedestrians. It is the future!

"Actually, it’s a really basic technology," says creator Max Pfeiffer, who studies human-computer interactions at Leibniz University of Hanover in Germany.

Indeed. As cool as it sounds, the underlying tech is pretty straightforward. To dictate walkers' routes, Pfeiffer simply attached electrodes (pilfered from a massage tool purchased on Amazon) to the thighs of 18 volunteers. When activated by a signal from a smartphone, the electrodes stimulated the sartorious, the long, thin muscle that connects the outer pelvis to the inner knee and controls the rotation of the leg. As long as the volunteer is providing forward locomotion, the sensation makes them turn.

Using a smartphone, Pfeiffer trailed his subjects as they walked through the streets with a smart phone connected to the electrodes. A push of the button on his phone caused them to veer right or left. The compulsion to turn wasn't overwhelming. "One comment from the participants was they always had the feeling that they can just take back control and override the signal," says Pfeiffer.

But what if he turned up the juice? Would his gadget be able to override someone's inborn locomotive system? Pfeiffer admits that he doesn't know, because he kept the voltage at a comfortable level. No one in the current study reported any sensation beyond a mild tingle.

Pfeiffer hopes this technology will help people appreciate the scenery by making them look up from their damned phones. Rather than walking around hunched over, pinching and pulling at their screen-based maps, they'd be free to—gasp!—look up, knowing that the marvel of modern technology will guide them along. (Alas, when freed from the responsibility of navigating, Pfeiffer says most of his volunteers wanted to check email as they walked.)

He says he envisions the technology being used for, say, downloadable walking tours. "You don’t actually think where you go, you just end up there," he says. When the controls get tighter—the turning radius is pretty wide at the moment—Pfeiffer envisions things like new video game-like sports, "where you can guide people to catch the ball or something." It could help you keep your eyes up when navigating through sketchy neighborhoods, or create a romantic roving mixtape leading your fiancee to an engagement ring.

Of course, the idea of surrendering your feet can easily turn sinister. If hijacked, the cruise control could drive you straight into the hands of a tech-savvy captor. Or navigation companies could sell "impulses" to advertisers, subtly nudging you towards places to relieve yourself of your money.

This isn't a new fear, and in fact predates Pfeiffer's pedestrian cruise control by more than a decade. A 2003 academic paper Geoslavery explored how then-nascent technologies like consumer GPS and location-based services could be used to kidnap people, quell political dissent, or influence buying decisions. "People thought I was futuristic when I mentioned the likelihood of devices that sting or burn to enforce rules. This one puts those devices to shame in terms of sophistication and control," says Jerome Dobson, a co-author of the paper, professor at Kansas State University, and president of the American Geographical Society.

Dobson says the electrodes seem easy to override, but warns that even things that seem fairly benign have a history of being abused. "Like human tracking itself, it's got many, many beneficial uses, but here's the old slippery slope argument all over again," he says.

And of course, it would be your choice whether to don the electrodes. "But we are quite far away" from this technology hitting the mainstream, Pfeiffer says. "What we built is just a prototype." This week, he is showcasing that early prototype at a human-computer interaction conference in Seoul.

In the future, though, the electrodes are small enough that they could easily be implemented into clothes. "The problem is the placement of the electrodes; you need to hit the muscles on the right place," says Pfeiffer. Otherwise, the muscle won't rotate and the navigation is useless. Watch out for that pole!