Optimized FT-Control with FTA Sensor - Robotized Transcranial Magnetic Stimulation - page 117

Fig. 7.1 The FTA sensor
(A) mounted to the robot's
end effector. A tool holder
(C) is mounted to the sensor
and the TMS coil (B)is
attached to the holder. A
small button (D) is attached
to the holder and connected to
the FTA sensor via the user
I/O port. The main
communication cable
(E) connects the FTA sensor
with the robot's internal
communication interface at
joint 4

Fig. 7.2 Pressed button
(below thumb) for activation
of hand-assisted positioning
during operation. The button
attached to the holder can
easily be pressed with the
thumb while holding the
TMS coil at its handle in an
intuitive fashion

query the status of the button on the robot controller. Only if the button is pressed,
hand-assisted positioning is active. We attach the button in such a way to the
holder that the user can easily press the button with the thumb while holding the
TMS coil at its handle in an intuitive fashion as illustrated in Fig. 7.2 . Note that,
using a joystick to move the coil instead of the small button was not accepted by
the users as it is non-intuitive for TMS users. On one hand, the button ensures that
the user has the hand on the TMS coil handle to hold the robot. And on the other
hand, it allows for fine positioning as no force/torque thresholds are used. Note that
by mounting the TMS coil with opposite direction into the handle, the button is
also easily accessible for left handed users.
For the implementation of hand-assisted positioning, we use the Adept robot's
real-time path modification. This allows for corrections of the robot motion in each
robot trajectory cycle. In such a way, we can directly react on the user interaction.
In each computation cycle the control scheme for optimized hand-assisted