Scooter skates

Each foot has a ski length thing with a small bicycle wheel at each end a handle comes up from the base. Unlike a scooter, the handle extends from the from to the back of the skate, so it's like a handrail. The wheelbase is long to prevent them tipping forward or backward, and you can hold onto the handrails to prevent yourself falling forwards or backwards (rather than depending on your ankle). Your ankle doesn't prevent falling forward or backward, because a hinge allows forward-backward tilt of the ski part to be independent of your foot angle. The hinge doesn't allow for sideways tilting though, it can only tilt sideways along with your whole leg. You wear boots that give good support.

The wheels are ratcheted so you can push against the ground to move forward, either in a running or sliding motion. The weight distribution has the centre of mass of the "scooter" at the foot hinge, so there's no tendency to tilt forward or back when it's lifted off the ground and moved forward or back. You can tilt it forward or back using the handle however.

There's a brake hand control on each handle, and accelerator. Use of the accelerator is optional as the ratchet mechanism lets you use it as a human powered system.

The steering mechanism steers the front wheel in the direction you tell it to turn, and the back wheel the opposite way.

The steering control is by turning your foot left or right. If you're already moving, it just steers with the wheels. If you're not already moving, it depends how far you turn your foot. At first it just steers the wheels proportionally to how much you've turned your foot. Once you've turned far enough to rotate on the spot, the steering stays there for a bit, so you can turn using the ratchet mechanism. And when you go a bit further than that, it powers the wheels to turn you. The steering input is scaled so you don't have to turn your foot 90 degrees or further to rotate on the spot.

You can use scooter skates in several ways: Hold the brakes and walk. Slide forward and back using the ratchet. Run using the ratchet (this may be tricky if you're letting go of the handles). Drive along using motor power, then step over obstacles.

The idea's loosely inspired by Tachikomas from the TV show Ghost in the Shell. They were quadruped robots with feet that also functioned as wheels. It made a really versatile combination. Ever since seeing them I've been trying to work out a wearable way to combine wheels with the stability of 4 wheels instead of 2, but keeping some of the versatility of legs/feet instead of having fixed wheels like a skateboard or car.