Society of Robots - Robot Forum

Software => Software => Topic started by: gonzo on December 22, 2010, 04:52:20 AM

Title: Problem about Robot_Arm_Designer Spreadsheet
Post by: gonzo on December 22, 2010, 04:52:20 AM

Hi, I'm gonzo from Indonesia.

Just want to inform that the Inverse Kinematic Calculation of the spreadsheet is wrong.

Because when I input the position along -X axis eg: (-8,0) the end effector points in the wrong direction.

That's the only problem I encounter till now.

I don't know if someone has posted thread like this before. I'm a newbie btw. ;D

I'll try to correct the formula. Hope that I can post it today.

REGARDS.
 ;)

Title: Re: Problem about Robot_Arm_Designer Spreadsheet
Post by: gonzo on December 22, 2010, 10:04:06 AM

SOLVED! ;D

For those who still don't understand, this topic is about an error
I found in the ms excel sheet "Robot Arm Calculator"
about inverse kinematic
http://www.societyofrobots.com/robot_arm_tutorial.shtml (http://www.societyofrobots.com/robot_arm_tutorial.shtml)

If you put an input (-8,0) the end effector points in the wrong position.
After doing some calculation, I realize the error is in the formula:

To solve the joint angle, you need to add 2 more variable which are:
K1: (C74) =D12+D13*C64
K2: (C75) =D13*C65

and for the theta and psi, rewrite
theta:(C66) =ATAN2(C62,C63)-ATAN2(C74,C75)
psi:    (C67) =ATAN2(C64,C65)

The graph should be O.K. now.
Regards

Title: Re: Problem about Robot_Arm_Designer Spreadsheet
Post by: Admin on January 11, 2011, 02:00:10 PM

Yea, I was too lazy to make it work in the negative coordinates . . . my bad . . .

Anyway, thanks for the code, I've updated the excel sheet :D