 Originally Posted by Invader
 Originally Posted by Ynot
That thing is inherently unstable, It's centre of gravity is way off the ground
Ideally, you want something a lot shorter if you want it to have any sort of stability
Also, the length of the legs will be a huge problem, as the stresses imposed to the middle of the segments would be huge
You;d either need far thicker legs, or far shorter legs
I actually expect the finished product to be quite lightweight. Standing at, say, the average hight of a three story apartment building, it would be ideal for the tripod to weigh less than small two door car. I'd like to use something along the lines of carbon fiber for the legs. I still have some research to do on structural materials, but carbon fiber seems at present to be the way to go. Considering it's cost, though... That'll be figured out in due time. As far as being top-heavy, I'd like the machine's legs to have a wide range of motion, which is to say that it should have the ability to splay its legs apart from each other over such a distance to greatly improve stability whenever it's stationary.
The finished product will have significantly thicker legs though, I agree.
Ok, average car is about 2 tonnes (2000kg)
I just don't see something that size being workable, the forces involved in just supporting 2000kg are enough
but, if like the Half-Life striders, you're wanting the robot to squat and extend it's hull (say being able to lower it's hull from it's natural 3 storey height down to 1 storey, and back up to 3) being able to move such a weight vertically with any reasonable speed would be astronimical
 Originally Posted by Invader
 Originally Posted by Ynot
Coupled with that. 3 legs are no good for stable momentum
take a look at nature. 2 legs or 4 legs
This crossed my mind as well, but upon observation of our example, the strider, it does appear to maintain a constant forward movement. It sways side to side momentarily it raises either of its forward legs. Granted, the movement doesn't appear efficient, but if it can be made to do the same thing in a real life example that would be perfect. I don't expect to make it run, so long as it can walk steadily.
I'll try to get an example of what it's movement looks like, probably by frapsing it in game.
Again going with the forces involved
If you have 2 legs in ground contact with 1 off ground, then a third of the hull's weight will be applying a angular (moment) force on the 2 legs
Not only will the 2 legs have to support the weight vertically, but also counteract angular force as well
 Originally Posted by Invader
 Originally Posted by Ynot
Once the central CPU can determine where all the segments are, you can program in the basic act of walking
Left hind, left front, right hind, right front
I want to avoid scripted movements, if possible. For movement I would instead preffer that the machine shifts it's center of gravity forward and then corrects the possition of it's legs with respect to the hull, while never actually reaching equilibrium again until it recieves some command to actually stop. I nottice that we walk in a similar fashion, by leaning forward first and then correcting the imbalance by moving our legs forward one after the other continuously until we decide to stop. If the main function of the machine is to correct and perform based on how it's balanced and positioned in space, it shoud also be able to perform over different types of terrain without having to be pre-programmed specifically for those types. Does that sound like a feasible option?
You need some sort baseline to work off of
The robot needs to know how to walk in an ideal situation (flat ground, no obsticales)
It'll alter it's walking movements depending on specific circumstances (gradient, etc.) but you need a baseline
 Originally Posted by Invader
 Originally Posted by Ynot
but the main CPU....
I think it's dependant on what you want the robot to do
Simplistic, non-learning navigation and movement could be done in a general purpose language
To balance and manuever on three legs is the primary function. I think that by using a series of if/when statements in the program that operate on the input of the sensors will fullfil most of that. And a general purpose language would be what exactly, C++ or Java? I know there are other languages used specifically for robots, but the ones I've seen only perform scripted movements similar to what you'd see assembly robots in a car factory doing. Again, I'm pretty limited with my understanding of the different languages, and what the ideal language would be for my situation. So long as it can crunch the information quickly enough to give the machine a more natural reaction time (like Big Dog in the video you linked), I'd get straight to work on learning it.
I recently picked up a book from the Sams series on C++ and started watching videos of a Stanford class on "Programming Methology", just to get my feet wet. It looks like something I'm going to enjoy getting into.
The programming will be quite complex
It won't be a single program, rather a suite of programs all running in parellel (and able to influence each other)
 Originally Posted by Invader
And again, thank you for the input, I look forward to hearing your part 2. 
Coming up now
 Originally Posted by Invader
How will we give it the ability to climb and descend inclines?
As above, you need a baseline
This is how we walk in an ideal situation
incline of 10 degrees = calculate changes in force = calculate change in movements to remain stable while moving = altered walking motion
 Originally Posted by Invader
-What kind of visual sensors are we using?
-Can we allow it to perceive depth?
-Is echolocation a possibility for mapping 3-dimensional changes in the environment?
Ah, surveying the land and interpreting. Probably the hardest part
Calculating movement based on known geography is easy(ish)
Translating the calculations into actual movement is easy
but getting terrain info into our system is difficult
We (humans) have it easy
We can look at terrain and determine whether it's easily passable even before we get there
We can even weigh up the pro's & con's on the quickest vs. safest route
We can extrapolate
Slugs will slither up to a rock, realise they can't go over it, and go around it
no forethought or extrapolation, but reacting only to the present
But our machine will have no actual "intellegence" at all
You have a whole heap of issues here
Simple depth perception is certainly possible, mimicing eyes with 2 cameras
(there's even a few algorithms floating about on the net)
But this assumes a lot of things,
like the robot magically "knows" what context these objects are in
Just picking a point and calculating it's distance is not the be all and end all
The robot will have to be able to determine what the object is, in relation to other terrain
The difference between an impassable wall, and a sloping floor, is purely a matter of gradiant
If you just look at the top of a slope, and work out it's distance away, how (programatically) do you differentiate that from the top of a wall?
One is passable (walk up the slope to the top)
One is not (bang into the wall)
The robot could very well spend all day, stationary, staring at an incline in the ground, crunching numbers, trying to determine if it's passable or not. Taking 2 steps then doing it all again.
There's a whole heap of problems with interpreting physical objects and terrain
 Originally Posted by Invader
MECHANICS!
-What are the legs composed of? Are we using hydraulics for the joints, and if so, can we get the joints to overextend?
Nyah, I'll skip this one
My first thought is using indirect motors (induction), rather than the use of hydraulics
(but only because I've never seen a self-moving machine use hydraulics)
When I think hydraulics, I think of slow, heavy lifting
not momentum
 Originally Posted by Invader
-Can we implement the use of heavy, heavy springs in the legs to give the machine a more natural "bounce" as it walks? Would this suffice as a form of shocks?
As above, I'd use motors
Induction motors would be good, as each segment would be free to move without directly affecting on the motor
Sensors could monitor the movement, determine whether we want this movement, and alter the motor to compensate
 Originally Posted by Invader
-The joint that merges the leg with the hull has a sort of 'ball and socket' type range of movement. How will we make that work?
Nyah, I'll skip this one too
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