# Robot cinematic model. Which method to get linear and angular speed?

• Patokun
In summary, the conversation discusses how to calculate the linear and angular speed of a robot with given x and y coordinates and an angle. The formula for calculating the speed is questioned and the importance of having all variables defined is highlighted. It is determined that having q1, q2, and q3 will allow for the calculation of x, y, r, and theta which can then be used to find the desired speeds.

#### Patokun

Hello all! I have a question regarding how to get the linear and angular speed for this robot for example (RRP).

http://img205.imageshack.us/img205/774/rrp.png [Broken]

I am given x and y or the hand, as well as theta (angle)

If I were asked to calculate the linear.

Do I derive x and y to q1, q2 and q3, and fill out the Jacobian matrix to get x' and y'?

Or do I use this formula, where V is speed, R is the rotation matrix, P is the position, etc.. The rotations are on the Z axis.

http://img842.imageshack.us/img842/4438/equationl.png [Broken]

Last edited by a moderator:
Welcome to PF, Patokun!

What do you mean by theta?
Is it the angle to the hand in polar coordinates?
If you have x and y, that would imply the angle in polar coordinates.

What do the symbols in your formula represent?

Btw, if you have x and y of the hand, your system in not fully defined yet.
There are many possibilities for q1, q2, q3 to get to a specific x and y.

If however, you have q1, q2, q3, you can set up a formula for x, y, and also for r, theta.
From those you can find linear speed and angular speed.