Unfortunately, joystick_teleop_node is almost unusable with a PS4 controller because axis 3 maps to the left trigger. Also, the emergency stop button maps to X on PS4 controller, although from the comments it seems like it should map to O which is generally PS4's equivalent to Xbox's B button.

I can implement this quickly and easily with an additional ~mapping parameter or such, defaulting to "xbox", but would also accept "ps4".