The Playa Crawler is a dieselpunk inspired one-person scout vehicle that utilizes the walking leg linkage developed by Theo Jansen. It was made to roam the alkali flats of the great Black Rock Desert. Created by Mark Ellis
FAQ:
Q: Can this go up stairs? I imagine if I tried that it would fall over backward. It likes flat ground. Q: What's the benefit of legs over traditional wheeled wheelchairs? A: None. In many ways it's worse! Q: So this isn't meant to replace conventional wheelchairs? It's not a medical device? A: Not at all. While I can't rule that sort of thing out if anyone else wants to try that it wasn't the goal of this machine. Q: Wait...so then what was the purpose of making this? A: For fun and because it's cool! That's good reason enough, right? Plus I wanted to have something to ride around on at Burning Man. I'd never seen anyone have Theo Jansens linkage used in a transportation vehicle before (well the Tin Spider came first by a long ways but it moves really really slowly because it's so large) and thought it would be a cool project to do. Q: Are the legs your invention? A: No they are the invention of Theo Jansen. He made them for his Strandbeest animal sculptures that are wind powered and roam on the beach. I merely adapted his leg linkage design for my Crawler. Everything else is just pretty dressing around that core mechanism. Q: How long did this take you to make? A: This idea has been floating around my head and on the back burner for the past 3-4 years ever since I first started going to Burning Man in 2011. I started construction in earnest in 2016 for Burning Man (their theme was "Da Vinci's Workshop" which seemed like the perfect theme to debut this thing) and got the lower half working but only for a few minutes before an essential part on the crankshaft broke. I finally got it working properly just recently this May for Maker Faire 2017 and I plan to have it fully built for Burning Man 2017. If you subtract all the waiting for parts to be made and shipped and all that then construction took only a few weeks. I designed it to be fairly easy to put together and take apart. Q: What's it made of? A: the vast majority of it is 1/8" laser cut aluminum. There are some structural body parts that are made from 1/4" aluminum that was water jet cut. The rest is a lot of steel rods and nuts and bolts. Q: What powers it? A: It's powered by two large brushless electric wheelchair motors and two large lead acid batteries. The motors and controller and joystick all come from a stripped down Invacare Arrow
Q: How fast can it go? A: Currently top speed is about a brisk walk or a walk-run but the legs rattle a lot when it's going fast so I tend not to run it that fast. Top speed of the Invacare Arrow that the motors come from is 7 MPH but there's a 2:1 gear reduction that cuts that in half and then the legs themselves don't carry it as far as the original wheels might have gone. Q: Can it turn? How does it turn? A: Yes it turns. It turns using skid-steering like a tank does by driving the two sets of legs at different speeds. For example if you drive the left side faster than the right then the Crawler turns right. It's technically possible to turn in place but the legs start to bend under the machine if you do that so it needs to take more gradual turns. It has about a 3-4 foot turning radius. Q: Can it go over rough terrain? A: Currently I'm not sure. It certainly likes nice hard level ground. I ran it into a pot hole and that caused too much strain on the legs and it broke a part of the crankshaft as a result. I'm hoping the addition of a slip clutch and more robust crankshaft and legs helps prevent that. Q: How much does it weigh? A: A lot. I've not yet tried to figure out how much exactly. The lower half without batteries needs two fairly strong people to lift. Q: Isn't this dangerous? There are a lot of pinch points in those legs. A: Only if you stick your hands in the leg mechanism while it's running. Please avoid doing that. Please keep your small curious children away. Q: If it's going to Burning Man aren't you worried about all the alkali dust? A: Yes but there's not too much I can do about it. All moving parts for all the art cars out there have to deal with the dust. I'll just have to see how well it performs when it gets out there. I'm sorta hoping enough lubrication will keep the dust from working into the joints too much but that might be a little too optimistic.
