Franka Emika Panda - Robot Sensitivity and Impedance

Franka Emika GmbH ©October 2018
35
Sensivity
The Arm has real torque sensors in all 7 joints. These enable, among other things,
to recognize and react to even the smallest forces acng on the Arm. This sensi-
vity facilitates numerous funconalies and capabilies, which are not possible
with convenonal industrial robots, such as impedance, guiding of the robot or
collision detecon. It should be noted that for achieving maximum sensivity it
is absolutely necessary to best possibly compensate addional forces acng on
the robot (e.g. a mounted end eector). This is why the end eector to be used
should be congured as precisely as possible in the admin secon of Desk.
Impedance is a behavior of the robot, which imitates the ability of a mechanical
spring. This behavior can be used to interact gently with the environment, for
example as not to damage fragile objects. The ability of changing impedance can
be seen as similar to that of a human arm, which tenses the muscles in order to
change rigidity and can adapt depending on the situaon, in order to increase
robustness when execung a task.
We have incorporated torque sensors in all seven axes. These provide informa-
on on the currently applied torques per axis at any given me. In combinaon
with our model-based control, deviaon between the expected torque and the
actual torque can be idened and the Arm can respond to it. For example, if
a user reaches into the moon path of the roboc arm when it is moving, this
will be recognized in real-me by one or several torque sensors. Such a torque
magnicaon is classied as a collision and can for example stop the robot’s
movement.
If the Arm is in intended contact with its surroundings, sensor signals of the
seven torque sensors can be used to generate a dened force on the point of
contact.
Impedance
Collision detecon and reacon
Generang forces