Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: frid4y on May 24, 2008, 11:18:29 AM

Title: Kinematics of a PPP robotic arm
Post by: frid4y 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 |

Title: Re: Kinematics of a PPP robotic arm
Post by: Kohanbash 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.

Title: Re: Kinematics of a PPP robotic arm
Post by: frid4y 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.

Title: Re: Kinematics of a PPP robotic arm
Post by: frid4y 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.