Strandbeest by Theo Jansen

Published on February 14, 2013

Theo Jansen’s work reminds to Leonardo da Vinci’s structures. Maybe just on the skeleton, the aesthetic of itself. Since 1990 Theo has been occupied creating new forms of life. Not pollen or seeds but plastic yellow tubes are used as the basic material of this new nature. He makes skeletons that are able to walk on the wind, so they don’t have to eat.

Over time, these skeletons have become increasingly better at surviving the elements such as storm and water and eventually he wants to put these animals out in herds on the beaches, so they will live their own lives.

Self-propelling beach animals like Animaris Percipiere have a stomach . This consists of recycled plastic bottles containing air that can be pumped up to a high pressure by the wind. This is done using a variety of bicycle pump, needless to say of plastic tubing. Several of these little pumps are driven by wings up at the front of the animal that flap in the breeze. It takes a few hours, but then the bottles are full. They contain a supply of potential wind. Take off the cap and the wind will emerge from the bottle at high speed. The trick is to get that untamed wind under control and use it to move the animal. For this, muscles are required. Beach animals have pushing muscles which get longer when told to do so. These consist of a tube containing another that is able to move in and out. There is a rubber ring on the end of the inner tube so that this acts as a piston. When the air runs from the bottles through a small pipe in the tube it pushes the piston outwards and the muscle lengthens. The beach animal’s muscle can best be likened to a bone that gets longer. Muscles can open taps to activate other muscles that open other taps, and so on. This creates control centres that can be compared to brains.

He can best explain how the leg works using a model he once made from a sheet of plywood. He often takes this model to lectures to demonstrate the leg’s action. In the middle of each beach animal is a kind of spine, more specifically a crankshaft. The remarkable thing about this spine is that it can rotate. In the model, his hand turns the crank of the crankshaft. This rotation is converted by 11 small rods into a walking movement drawn by a small pencil at the end of the leg. Let’s call this pencil the toe.

Ideally, the pencil describes a kind of triangle with rounded corners and a horizontal base. Whenever the toe is on this base, it touches the ground and carries the animal. It describes a horizontal line, or rather the entire animal does, since the toe is carrying the animal. The same holds for a wheel; the axle also describes a horizontal straight line. The beach animal doesn’t lurch. When the toe reaches the end of the base (at right), the leg is lifted whereupon it rapidly describes the other two sides of the triangle. During that time the animal is supported by the other legs which at this stage are on the ground. The above curve is the ideal walking curve; a flat base with rounded corners. The curve this produces is dependent on the ratio between the lengths of the 11 small rods. Another ratio gives an entirely different curve, a figure 8 for example. Of course, he had no idea beforehand which ratio between the lengths he needed for the ideal walking movement. Which is why he developed a computer model to find this out for him.

But even for the computer the number of possible ratios between 11 rods was immense. Suppose every rod can have 10 different lengths, then there are 10,000,000,000,000 possible curves. If the computer were to go through all these possibilities systematically, it would be kept busy for 100,000 years. He didn’t have this much time, which is why he opted for the evolutionary method.

Fifteen hundred legs with rods of random length were generated in the computer. It then assessed which of these approached the ideal walking curve. Out of the 1500, the computer selected the best 100. These were awarded the privilege of reproduction. Their rods were copied and combined into 1500 new legs. These 1500 new legs exhibited similarities with their parent legs and once again were assessed on their resemblance to the ideal curve. This process went through many generations during which the computer was on for weeks, months even, day and night. It finally resulted in eleven numbers denoting the ideal lengths of the required rods. The ultimate outcome of all this was the leg of Animaris Currens Vulgaris. This was the first beach animal to walk. And yet now and then Vulgaris was dead set against the idea of walking. A new computer evolution produced the legs of the generations that followed.

These, then, are the holy numbers: a = 38, b = 41.5, c = 39.3, d = 40.1, e = 55.8, f = 39.4, g = 36.7, h = 65.7, i = 49, j = 50, k = 61.9, l=7.8, m=15 . It is thanks to these numbers that the animals walk the way they do.

Theo Jansen

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