robot controls

hi, i m an electronics engineer and want to make a android.. i have started in respect of my electronics.. to go ahead.. i need more respective
mecnanical engineering behing robotic.. can any body help me to kno where can i get good sourse for that or can u tell your self.. it should v simple to learn for an electronics engineer.. i m not seeking about devece but how that devic or tool will help me to know how it will help balancing and free for movement.. eg. hand, elbow, leg.. etc. ok i m telling my current need.. i want to make robotic arm with full freedom for movment like a human arm.. which concept i should use motor or hydrolic.. will hydrolic be cheap.. will that arm help my robo to hit a ball by a bat, if i will give such signal by electronics, in any position in free space.. I would like to design my robo parts by my convenience .. have a great day
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
abhi wrote:

Good luck - I hope you have a good record with you're bank manager ;). The Honda corporation have spent millions on getting something to plod about and shake peoples hands. (I know its a bit more advanced than that but it certainly looks that way on the videos I've seen)

A lot of my engineering knowledge has come from taking VCRs to pieces and reading... a LOT. Of course it would help a great deal to take a collage or university course in mechanical engineering.

Depends on what you mean - an arm (without a hand) has seven degrees of freedom - meaning you could control it with seven actuators. Seven 15 servos comes out at 105. Hydraulics are slightly over-kill if you are just building a robot for show. They can also be lethal if you are not used to them (I've never used them and I probably won't unless I get some formal education in them). They are NOT cheap either. A small ram could cost 20 - thats 140 before you start on the pumps, pipes and valves. A nice alternative has been invented by the Shadow Robot company. It's called a pneumatic muscle and has similar characteristics to biological muscle. http://www.shadowrobot.com/airmuscles/overview.shtml

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I am not sure what you mean here, are you talking about "positional feedback" as to where the hand or leg is at some point in time? If so, then you will need to do a lot of studying. There are open and closed feedback systems. In other words, you tell a servo to go to position "130" degrees and assume it does it. Or a closed system where there is a sensor which is not part of the servo (as an example) and the external sensor determines the location of the object.
There are many ways to do this, so study, study, study.

Here is an overview on the main types of drive systems. These are generalities, you can always make an exception if you have the time and money.
Hydraulics tend to be heavy and messy and will always leak somewhere. Hydraulics are best for power, but not really speed unless you want to spend lots of R&R time and money. Watch the average bulldozer for an example.
Electric is more controllable for less money but less powerful except for short bursts. Batteries must be considered re: weight and placement. Heavy wires are needed to convey energy to arms and legs and as you know, heavier wires are not reliable under repeat bending. Hoses are.
Air is fast, light, controllable but less accurate in general than the other two mentioned. However, it also seems to produce motion which is more human like. It is less powerful than hydraulic and in general less powerful than electric unless you spend a little time with R&R again. Because air compresses, you might need a constant feedback system to maintain accuracy in holding a position.
Using hoses, the repeat bending is not a big problem and leaks can be patched with minimal mess. The source of the air power can be almost anywhere on the unit, but large, fast motions will call for large reserve tanks or highly compressed air tanks & valves for fast releasing of air. Might be some noise issues.
Just some thoughts,
HobbyBot
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.