### Author Topic: Kinematics of a PPP robotic arm  (Read 2445 times)

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#### frid4y

• Jr. Member
• Posts: 8
##### Kinematics of a PPP robotic arm
« on: May 24, 2008, 11:18:29 AM »
I have attached the schematic of a prismatic robot arm which i am trying to calculate the forward kinematics but i have come up to the following Jacobian which i would like to find out if it is correct and if not if someone could help me out.

| 0 0 0 |
| 1 1 0 |
| 0 0 1 |
| 0 0 0 |
| 0 0 0 |
| 0 0 0 |
« Last Edit: May 24, 2008, 11:19:25 AM by frid4y »

#### Kohanbash

• Supreme Robot
• Posts: 430
##### Re: Kinematics of a PPP robotic arm
« Reply #1 on: May 24, 2008, 07:45:25 PM »
Hi
At first glance I would say that is incorrect. What are the units associated with the arm.
Robots for Roboticists Blog - http://robotsforroboticists.com/

#### frid4y

• Jr. Member
• Posts: 8
##### Re: Kinematics of a PPP robotic arm
« Reply #2 on: May 25, 2008, 05:39:28 AM »
I tried solving it again and i calculated that the Jacobian is

| 0 -1  0 |
| 1  0  0 |
J=  | 0  0  1 |
| 0  0  0 |
| 0  0  0 |
| 0  0  0 |

whereas the angular velocity is zero so Jw (omega) is zero and the linear velocity is
| 0 -1  0 |
| 1  0  0 |
| 0  0  1 |
for the Zo Z1 and Z2 are 0 1 0, -1 0 0 , and 0 0 1 each.
Let me know if this is not right. The forwards kinematics T3 final table is
| 0  0 -1 -d3 |
| 0  1  0  d2 |
| 1  0  0  d1 |
| 0  0  0   1 |
which therefore shows that the Jacobian is completely not dependent on the prismatic links length.
« Last Edit: May 26, 2008, 12:01:40 PM by frid4y »

#### frid4y

• Jr. Member
• Posts: 8
##### Re: Kinematics of a PPP robotic arm
« Reply #3 on: May 29, 2008, 07:58:23 AM »
does anyone know if the final is correct? please help me out. i don't know people with the specific knowledge to help me out. thnx.