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Hi There,
I have a six wheeled wild thumper that I am using for my final year project for university. I need to transform the linear.x and angular.z velocities into left and right motor commands.
Have you any idea how this is possible?
The default wild thumper can not measure its speed, which is required. Did you add encoder to the motors?
You basicly need to transform the linear and angular velocity into speeds for the left and right motors, something like
float speed_wish_right = (cmd_vel.angle*WHEEL_DIST)/2 + cmd_vel.speed;
float speed_wish_left = cmd_vel.speed*2-speed_wish_right;
with WHEEL_DIST as the distance between left and right wheels (25.2cm on my wild thumper), cmd_vel.angle is the angular z component and cmd_vel.speed the linear x component.
I would personally go for something like the ros_controldiff_drive_controller, as that does all these things for you - and more.
Of course, this does not remove the need for encoders, as @Humpelstilzchen already noted.
This will be very difficult, most ros packages expect that you satisfy their velocity. But if you e.g. just want to teleop it doesn't really matter.
default unit for ros is linear: m/s, angular: rad/s
Im not too sure about that, I landed up using the differential_drive ( http://wiki.ros.org/differential_drive ) package which does it for you.
Asked: 2015-05-27 01:13:49 -0500
Seen: 7,762 times
Last updated: Aug 13 '16
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