  While the search for new solvents in the chemical industry is of uttermost
importance with respect to environmental considerations, this domain remains
strongly tied to highly manual and visual inspection tasks by human experts. As
the manipulated chemicals may imply a critical danger (CMR substances),
mechanical protection barrier are used (fume hoods, gloveboxes). This, in turn,
can induce postural discomfort in the long term. Carrying out this task using a
remotely controlled robot to reproduce the desired vial motions would alleviate
these postural constraints. Nevertheless, the adoption of such a system will
depend on its ability to transcribe the users' expertise. Particular attention
must be paid to the intuitiveness of the system : transparency of the actions
performed, relevance of the perceptual feedback, etc. and, in particular, the
fidelity of the movements performed in relation to the user's commands.
However, the extent of the rotational movements to be generated and the task
interactivity complicates the problem both from the point of view of the motor
capacities of industrial robots and for the transparency/responsiveness of the
control.To tackle the problen of guaranteeing a secure and reactive expression
of the manual characteristics of this task, we propose to separate the control
of movement into two parts: control of the path (set of spatial poses) and of
the trajectories associated with this path (speed, direction of travel along
the path). The user can then partially control the robot's movements, by
choosing the type of generic, secure path and modulating the trajectory
performed on this path in real time. Although this drastically limits the
possibilities for interaction, we assume that this teleoperated system can
enable this type of observation task to be carried out as effectively as for
direct manipulation. This hypothesis was tested through an experiment in which
a reading task, less dangerous but with similar characteristics to the
application task, had to be performed using different variants of trajectory
modulation. This experiment consisted in reading words printed on four white
capsules (dimensions 6 x 12 mm) placed into cylindrical vials ( dimensions 16
mm x 70 mm). Four randomly selected vials were tested by each variant. Firstly,
users had to perform the task via direct handling, then under conditions
secured by a protection barrier. Users were then invited to perform the task
using different trajectory modulation variants (modulation and passive viewing
of a pre-recorded video, modulation of the trajectory of a Franka-Emika Panda
robot performing the task in real time in front of a monocular Logitech Brio 4K
camera). After each trial of a variant, users evaluate different aspects of
this variant (manual and visual performance, ease of use, acceptability of the
interface) through a questionnaire. During the trials, various objective
criteria are also measured (number and nature of interaction with the
interface, time and degree of success in the task). This experiment was carried
out with 37 subjects (age : 27$\pm$5, 20 females). The data recorded showed
that the proportion of successes, as well as the subjects' perceptions of
visual performance, comfort of use and acceptability of the interface, were
similar and high for all the variants. This suggests that this task is indeed
achievable via the proposed interface. However, data also showed that average
task completion times when using the trajectory modulation variants were
significantly higher than handling by hand variants, which implies that the
proposed remote semi-automatic control procedure fails to achieve satisfactory
performance regarding execution time. An interface allowing more reactive
manipulation of the vial's movements seems necessary, and will be tested in a
future experiment.
