如何在ROS中编写多个Twist消息

Question

I'm trying to build two virtual joysticks using differential_drive package in ROS using Python (new as well) for my mecanum wheel project (ability to do sideways movement joystick). Since both uses the same file type Twist how do I make two outputs to be published? Does twist only understand linear or should I change it to linear2 as well?

original:

self.twist = Twist()
self.twist.linear.x = (1-self.y) * (x_max - x_min) + x_min
self.twist.linear.y = 0

etc.

Do I have to change like this:

self.twist2 = Twist()
self.twist2.linear.x = (1-self.y) * (x_max - x_min) + x_min
self.twist2.linear.y = 0

or:

self.twist2 = Twist()
self.twist2.linear2.x = (1-self.y) * (x_max - x_min) + x_min
self.twist2.linear2.y = 0

Both Virtual Joystick (original) and Virtual Joystick 2 (modified) have to be on at launch

Answer 1

The first one is correct

 self.twist2 = Twist() self.twist2.linear.x = (1-self.y) * (x_max - x_min) + x_min self.twist2.linear.y = 0 

twist2 is just an arbitrary name of the variable. linear is a member of the Twist instance, which has always the same name, no matter how you call the variable.

You could have easily figured that out yourself by just trying it, though (the second one would raise an error).