QB Robotics qbmove Advanced Kit, User Manual

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81
28 aprile 2021
[2] devices connected:
[ INFO] [1524044525.218696997]: - device
[1] connected through [/dev/ttyUSB0]
[ INFO] [1524044525.218736612]: - device
[2] connected through [/dev/ttyUSB1]
When the Communication Handler is on, it provides all the Services required to interact with the
connected devices: e.g.
get info or measurements, activate or deactivate motors, set commands ,
and even more... A detailed description of the services can be found in the qb_device_driver
package wiki.
6.5.2.3 Control
As shown before, the control Node exploits the ros_control Controller Manager which loads and
runs the device controllers. Each controller provides an Action Server that, together with the
Hardware Interface structure, allows the user to send commands to the relative device and get
its measurements.
From an API point of view, it is implemented an Action Client which matches the relative
trajectory controller and provides a method to send Goals, i.e. command references, directly to
the
given device. Additionally, the Action Client is subscribed to a Topic
(
*_controller/command
) that can be used to send reference commands from outside the
code, e.g. asynchronously from the command line, or from a higher-level control Node, e.g. as a
result of a planning algorithm.
It is recommended not to mix these two control modes: choose either to control the device
directly from the code by extending our API or through this command Topic.
Regardless the control mode chosen for the given application, and apart form a customization
of the API, the following launch file templates can be used respectively to control several devices
or a single one: