Oneirophage's Xanga Site

Saturday, April 19, 2008

Gone

Just to cater for the very remote possibility that someone, somewhere reads this, I'm unlikely to be posting more. To say "ever" would be making a bit much of an assumption, but not that much. Real world far too involved for me to be doing this...

Sunday, February 03, 2008

Verbal

Verbal verbal verbal.

Saturday, February 02, 2008

Legs

I can sense that this is going to be a long one. And unlike the other ones, I'm going to abandon all pretence, and just say what I want to say!

Legs are good. You can make them look like anything. I'm going to look at a few good legs I've done (the Ant Tank I'll probably go into in depth some other time).

This is the leg to my Glass Spider (http://aleph-.deviantart.com/art/Glass-Armour-45388958)
The main idea here was to have something which looked strong and pretty. I started with the internals: simple cylnders and spheres with bevelled edges, to look as if it would work. The main joints were just spheres, leaving everything to the imagination, but on the second segment there was another cylinder, which could be some kind of motor. Then there are various pistons, but they're all basically round, trying to make it look protected. It's reflective to pick up the colours I knew I'd use later.

As for the joint coverings, they're all made up from hollow ellipsoids. These were put into position and had ellipses cut out of them, and the outside edges rounded. This retained the roundness, but allowed some sharp parts. The thickness of the shell was made quite high, to make them look sturdier and to allow the edges to be rounded. The material was made 2-tone for two reasons: first, it's pretty, and secondly, it brings out the shape. The second tone in the highlights was achieved by making it reflect some colours more than others, but transmit them all equally (so only the overall colour had an effect on the transmittance. The transparency means that you can see the innards, which look more detailed because of the reflections of the shells.

(http://aleph-.deviantart.com/art/SPM15-Mosquito-63230221)
The aim with this leg, from a miniature mosquito robot, was quite different. I wanted it to look quite low-tech, spindly, and as if it was bending under the weight of the robot (like how a mosquito's legs splay). I decided to use concertina-folded rubber for the joints, the idea being that if air was pumped into them, they would straighten, and if it was removed, the springs on the side would make them fold again. The wires all had to be small, and look as if they were one wire running down each side of the leg - this adds some sense of elegance and economy of design. Small corners were all rounded, to make it look as if it was small enough that only a certain level of detail was possible. The tubes around the bottom parts of the legs could act as both stress and touch sensors, with their outputs travelling up the metal wires (again, design economy, but it would be risky in the wet). Both this and the glass spider have many legs, and so do not need large feet for balance.

(http://aleph-.deviantart.com/art/HERAKLES-Powersuit-52744094)
Here, the aim was to augment a person's normal power, and to look industral. Thus there are large, strong joints, but the pistons themselves are relatively small - just enough to make the pilot able to use the suit, and be slightly stronger than normal. The cables bulk up the week-looking pistons (they can be made out of really strong materials, but still need enough power to work - electric pistons of that size would be puny). They also add to the industrial look. Large feet give the impression of stability.

Although the leg is armoured, it's not complete. The metal parts don't cover the joints (so as not to restrict the range of movement), and are positioned so that they could detect the pilot's movements. The armour plates are a different colour, to contrast with both the pipes and the pilot's skin, and are unrealistic: they are neither in contact with any other components, nor do they cover the whole body, or all the tubes. The reason for this was to show more of the pilot, making them seem more exposed, even in such a hefty piece of equipment.

The Ant Tank's legs are different again. The overall shape is an ellipsoid, but it is cut and altered enough to look quite different. It does, however, lend a structural unity, without being too blocky. The contrast of the rounded base shape with the angular cuts adds interest, as do the insets. The radiator-like strips on the lower legs fill in an otherwise blank area, and hint at a high-powered device which needs to keep cool, as do the vents on the tops of the lower legs. The shininess of the armour could look fragile, but here it is coupled with sturdy legs and a strong shape (all convex), and the transparent parts are dark enough not to look ephemeral. Like in the 'mech's legs, not all the armour plates are attached: here, they are magnetically suspended to absorb the force of blasts.

The relatively weak-looking exposed joint on the top is protected by a pair of rollbars. These not only cover the components, they draw the eye away from them, break their outline, and bulk up the legs, giving a greater impression of toughness. The idea of a tough mech is carried to the internals. Rather than having exposed joints, the moving parts have multiple slats over them (in a different colour for emphasis), adding more detail as well. The pistons are all large and well covered. The network of green pipes between the pistons and the rounded cylinders (which are reminiscent of compressed air cylinders, even if they are not) add more detail, and use of green for the tubes helps bring out the details in what would otherwise be a rather monochromatic machine. the oddly protruding cylinders and plate on the upper leg are novel, but do actually serve a purpose in allowing the piston to move. They also suggest that the tank is not hugely worried about attack from beneath, suggesting scale.

The feet follow the same pattern of shielding, and their size and position underneath the legs adds to the impression of strength. The spikes underneath them (again in green to make them more visible) could be folded up, and allow the tank to have extra grip when needed, hinting as to its uses.

Next time i'll look more closely at the other parts of the Ant Tank, seeing how it works, why it's the way it is, and how other things can use the same principles. If you've managed to read all that, thanks, and well done. If you actually found it useful or enjoyable, please comment here or at http://aleph-.deviantart.com/, I'd like to know!

Tuesday, January 29, 2008

Terrestrial Locomotion...

...is a really fancy way of saying moving on land.

Wheels. I'm going to say it straight, wheels. An easy way to make something move, on land, is to put it on rolly things. The wheel is good because of its simplicity - you need a motor, of some description, and probably some gears, to power it. Of course, it's not really that simple, but it's not that hard.

You have to think about size and number. It's possible to get by with one, but it's hard. Two are good for things that go fast, or which need to be small (motorbikes vs scooters). Three allows for static stability, and a lack of wobbling, but tricycles have been known to flip; the inherently triangular nature of them leads to a tendency to go up on two wheels while cornering at high speed.

Four is, of course, the charm, and you see four-wheelers everywhere. Beyond that, it's mostly a matter of supporting large vehicles (like lorries), or stability. Note that it's not really about weight: the huge off-road dump trucks, capable of carrying insane amounts of rock, have four wheels. They're just immense. In contrast, the tiny Mars rovers had six wheels, to allow them to cross obstacles more easily. You often see setups like this with complicated positioning systems for the wheels, to help with that.

Suspension can be complex, like in that case, but it can also be relatively simple, designed to absorb shocks. At its simplest, the only real variable is how hard the suspension is, whether it squishes easily or lets you feel every pebble. Then you can have larger suspensions, possibly with hydraulics to raise and lower the vehicle, or individual wheels (some anti-tank guns did their vertical aiming using their suspension).

Then there's the wheel's size and properties. Larger wheels will be less affected by small holes, but will still feel bumps (suspension notwithstanding). Then there are the tyres, which could just be rubber for grip and a small amount of give, or pneumatic (but still firm - energy is lost in deforming squashy tyres), or something else, possibly complex rubber structures creating the effect of suspension, or an actual suspension system inside the wheel (see the tracks later on). Tracks give grip off-road, and help in wet conditions, whereas smooth tyres give great grip on roads, but are useless in the wet. Other effects such as chains or spikes add interest and are a clear indicator of the vehicle's environment.

Tracks have similar issues: suspension and power, but one also has to consider how the track is pulled along buy the wheels, and what the track does. A rubber track is easy to model would be less sturdy than a metal one, but would have grip. Metal tracks (or rubber ones for that matter) could have embellishments to aid grip, and to add to the realism by showing how the mechanisms work. An exposed hinge would be a point of weakness, but hinge covers would serve to add realism, and show that the machine is designed to be strong. The workings could also be covered with a skirt to the same effect.

Here there are mechanisms for altering the shape of the track, to allow it to cross more difficult terrain. However, the gears are small and weak, and the mechanisms are exposed, suggesting poor design.

Before covering legs, it's good to mention other concepts, such as hovercraft (can be fast, need not worry about small bumps, but can be horrid to steer), which would need skirts for lift, some form of forward propulsion and steering, probably including tail fins to help it keep going in the right direction, as well as some sort of air intake, and at least an implication of a mechanism to keep it afloat. Hovercraft could also travel across water, but very rough terrain would be a problem, and economies of weight would have to be made to allow it to hover.

Finally, there's always the Ekranoplan, or ground-effect craft. These use relatively little power at speed, but have to keep moving at speed, or they'll stop, which limits their usefulness unless they have some other option. These are characterised by large, flat wings, angled up to force the air beneath them.

I haven't covered things like rail tracks, since I want to focus on autonomous devices. And I'm lazy, and just doing this for fun (who am I kidding, nobody's going to read it). Next one will be on legs, and will have more pictures! And more text, since I do spider robots.