Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: RITESH29 on October 04, 2011, 08:34:34 AM

Title: How to make robot arm.....??
Post by: RITESH29 on October 04, 2011, 08:34:34 AM

Hi guys,

I find this cool place for mechanical work for robots..!!

OK, i am new to mechanical design as i am an electrical and electronics student. designing mechanical work is not easy in begging for me ..as i have too design a robot arm which i will connect to my robot,etc...

So, i want some basic help to design an arm...please guys help me..!!
Thanks

Title: Re: How to make robot arm.....??
Post by: KurtEck on October 04, 2011, 09:21:43 AM

You can always start by looking at places that make and sell hobby Robotic arms.  Example Lynxmotion (http://www.lynxmotion.com/c-27-robotic-arms.aspx (http://www.lynxmotion.com/c-27-robotic-arms.aspx)).   Also there is discussions about arm designs up on their forums...

A lot of your design will be dictated by your requirements.  For example do you have a specification of how large of a reach do you need?  How much weight it needs to handle?  Do you need a gripper at the end, or maybe a suction cup design, ...

Good Luck
Kurt

Title: Re: How to make robot arm.....??
Post by: RITESH29 on October 04, 2011, 09:24:42 AM

OK, if you want to know what load it should lift then this video can tell and yes i need gripper also to lift...
here in video you can see in person robot ( manual)
ABU Robocon 2012 Hong Kong Game Rule (http://www.youtube.com/watch?v=qeZ4er9Xzjs#)

Title: Re: How to make robot arm.....??
Post by: RITESH29 on October 08, 2011, 12:33:30 AM

Hi,
for making arm of robot which motor hould be used...
Here is the link..
http://robokits.co.in/shop/index.php?main_page=index&cPath=2 (http://robokits.co.in/shop/index.php?main_page=index&cPath=2)
Thanks

Title: Re: How to make robot arm.....??
Post by: RITESH29 on October 10, 2011, 08:22:56 AM

help please...

Title: Re: How to make robot arm.....??
Post by: newInRobotics on October 11, 2011, 12:57:41 AM

Well, to start with, You need servos and not motors for the arm. Now, torque and angular velocity of the servos required depend on the weight Your robot will have to lift (plus weight of an arm itself) and also length of Your arm (lengths of bits in between servos), and how fast that weight will have to moved around. As we know nothing about the arm You are planing to build - we cannot help You with this at all.

Title: Re: How to make robot arm.....??
Post by: RITESH29 on October 11, 2011, 09:59:07 AM

OK, i think it should lift at least  400gm and the length should be of 10-15cm...I think the speed will work fine in 50-100RPM.

last is your wish according to your great experience.

Title: Re: How to make robot arm.....??
Post by: newInRobotics on October 11, 2011, 01:02:58 PM

Quote from: RITESH29 on October 11, 2011, 09:59:07 AM

OK, i think it should lift at least  400gm and the length should be of 10-15cm...I think the speed will work fine in 50-100RPM.

At least is not good enough, You must consider worst case scenario. Also, You have to consider weight of an arm itself as it is also affected by gravity  ;)


You can calculate torque requirements Yourself:

F - force
a - acceleration
m - mass
T - torque
r - radius

F = a * m;
T = F * r;


With details that You provided comes the following:

a = 9.81m/s*s
m = 400g = 0.4kg
r = 15cm = 0.15m

F = 9.81 * 0.4 = 3.924N
T = 3.924 * 0.15 = 0.5886Nm

Title: Re: How to make robot arm.....??
Post by: RITESH29 on October 11, 2011, 09:33:01 PM

OK, please have a look on this and tell which servo should be used at bottom....
http://robokits.co.in/shop/index.php?main_page=index&cPath=2 (http://robokits.co.in/shop/index.php?main_page=index&cPath=2)

Title: Re: How to make robot arm.....??
Post by: newInRobotics on October 12, 2011, 12:32:08 AM

Quote from: RITESH29 on October 11, 2011, 09:33:01 PM

OK, please have a look on this and tell which servo should be used at bottom....
http://robokits.co.in/shop/index.php?main_page=index&cPath=2 (http://robokits.co.in/shop/index.php?main_page=index&cPath=2)

I don't know, as You do not provide me with enough data (as explained in my previous post). Do not expect people to do something for You if You're not willing to study the topic Yourself.

Edit: From calculations above (which are NOT to be used as all relevant factors are NOT taken into account), Standard Dual Ball Bearing Servo 7kg/cm (~0.69Nm) @ 6V (http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2&products_id=187) can be used.

Title: Re: How to make robot arm.....??
Post by: RITESH29 on October 12, 2011, 01:37:20 AM

But i think one problem can arrive, that will be how i will fix up shaft that to arm there is no nut and bold in motor...

Title: Re: How to make robot arm.....??
Post by: newInRobotics on October 12, 2011, 03:07:12 AM

Have a closer look  ;)

(http://robokits.co.in/shop/bmz_cache/3/3f5b5dfc9a52b2bbbaa00a3e2f81addc.image.150x105.jpg)
(http://robokits.co.in/shop/bmz_cache/c/c56d6327a9c630f7b2556d2433b6d30a.image.150x105.jpg)

Title: Re: How to make robot arm.....??
Post by: RITESH29 on October 13, 2011, 10:54:53 PM

Hi again,

any idea about the controller switch used in pneumatic system to control the air pressure electrically..?

Title: Re: How to make robot arm.....??
Post by: newInRobotics on October 14, 2011, 12:19:04 AM

Air valve with an actuator attached I guess... Quick Google (http://www.google.co.uk/search?q=solenoid+air+valve+tutorial&hl=en&source=hp&gs_sm=e&gs_upl=5258l10625l0l10859l16l15l0l1l1l0l203l1639l5.8.1l14l0&oq=solenoid+air+valve+tutorial&aq=f&aqi=&aql=1) search should yield You useful results.