joy changes setpoint after initial click on LT and RT

[aksell]

joy_node from joy sets a value between -1 and 1 for both LT and RT on the Xbox 360 Wired Controller. After the initial click the setpoint on LT and RT change from 0 to 1.

Reproduce error by running

• rosrun joy joy_node

joy is built upon xboxdrv, when xboxdrv is inspected directly LT and RT seem fine.

[aksell]

We could eliminate the need to pres LT and RT on startup by introducing a if statement in joystick_interface

if first click:
    "workaround problem"
else:
    "do as usual"