Ah, I hadn't thought about using stepper motors (I've never looked into how difficult the control would be).  Would this package be of any use to you?  I would assume you could kludge it to work, but I don't know if it really helps.

I will have to think about the holonomic controller.  (I don't have access to that paper here, I'll get it later today)  That will be difficult to debug because I don't have a holonomic robot.  But I suppose I could use the holonomic controller on a non-holonomic robot, right?

-Jon 


On Wed, Feb 20, 2013 at 5:20 AM, Claudio Carbone <cla_carbone@tiscali.it> wrote:
Nice work Jon.
I'll check the code one of these days.
In my university our diff robots are so small and cheap they have steppers rather than encoders

One thing I can think can expand your stack is a holonomic controller:
lin_spd=cos(robot_theta) *vx+sin(robot_theta)*vy;
ang_spd=-( 1/d )*sin(robot_theta) *vx+(1/d)*cos(robot_theta)*vy;

d being the distance from the actual drive center (the pivoting point of the platform) along the longitudinal axis of the robot (the forward movement axis).
Then going from (lin_spd, ang_spd) to (wheel_1, wheel_2) is trivial.

Relevant article:
Bilateral Teleoperation of a Formation of Nonholonomic Mobile Robots
Under Constant Time Delay
Oscar M. Palafox and Mark W. Spong
(can't attach here)


Best regards
--

Eng. Claudio Carbone
Embedded Systems Design

P.IVA: 11688471009
tel: +393809017424
email: Send email
My linkedin profile

My Portfolio
My portfolio site

 



--

Eng. Claudio Carbone
Embedded Systems Design

P.IVA: 11688471009
tel: +393809017424
email: Send email
My linkedin profile

My Portfolio
My portfolio site

 


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