Hi, my name is Elodie BOUZBIB, I’m a PhD student at Sorbonne Université, and I’m
about to introduce CoVR, a novel robotic interface providing strong kinaesthetic feedback in
a room scale VR arena, that we developed with my supervisors Gilles Bailly, Sinan Haliyo
and Pascal Frey.
A main challenge in VR is the lack of convincing haptic feedback.
It is common to use controllers.
They may vibrate when we virtually touch a wall for instance but they do not constrain
the user as they focus on the users hands and do not provide force-feedback on the whole-body,
so eventually the user is more likely to go through the wall.
This presentation aims at demonstrating that virtual reality can benefit from large-scale
force-feedback and shows an interface that enables it.
Hardware-wise, CoVR is a physical column mounted on a grounded XY Cartesian ceiling robot,
that dynamically overlays multiple virtual objects.
Software-wise, it predicts which object to overlay.
For instance, here, the user is free to interact with any part of the wall, with no regards
to the scenario’s progress, and when the user is moving, the system is moving accordingly,
to overlay the predicted part of the wall prior to the interaction.
Let’s take a top view of the arena, with CoVR at the bottom right.
First, to avoid CoVR going through the user when this latter in on its trajectory to reach
an object of interest, we attached a virtual cone-shaped obstacle around the user, so CoVR
naturally avoids it.
In a non-deterministic scenario, where multiple objects are available, CoVR naturally moves
at the barycentre of all the objects of interest positions.
To be able to move, it is actually attracted to the different virtual objects with a spring
damper model, where their stiffnesses are converted into weights.
The weights are a function of the users’ HMD position and orientation.
We evaluated our model in a technical evaluation to find the relative contribution of the distance
over the orientation and to test CoVR’s ability to physically overlay the correct
target prior to the user interaction.
When a weight is equal to 1, the object has been chosen.
We found the parameter is independent from the number of distractors in the scene and
the optimal one provided a little over 80% of success rate in an entirely uncontrolled
environment.
This can be increased up to 95% with a scenario-based model, when we add for instance a 75% prior
probability for the target to be interacted with among all the available objects.
Now that we defined that CoVR allows for non-deterministic scenarios, let’s define how to interact
with CoVR.
One of CoVR's key features is to have the capacity of resisting to body-scaled users
actions, such as pushing on rigid walls or even leaning,
crunching under or going into it.
We create interactions on CoVR's panels, made of cardboard, for instance users can explore
the environment to find a haptic code.
Also, on CoVR's skeleton, we can mechanically attach props, to enable directed manipulation,
replicating for instance a slot machine.
CoVR can carry multiple potentially heavy objects (up to 80kg) that users can freely
manipulate or make interact with each other.
For instance, here, the user is freely manipulating a cube that does not physically fit in the
locker.
CoVR provides strong traction forces.
For instance, CoVR can act on the users by pulling them and leading them through forces,
simulating travelling on a magic broom, but it also enables to literally transport the
users.
CoVR can also physically initiate the interaction with the user, for instance a fabric can slightly
brush the users' head to simulate the crossing of a ghost.
To sum it up, CoVR does not constrain the users to hold continuously a controller and
it encounters the user when an interaction is required.
Whenever CoVR is static, it allows both bare-hands exploration and manipulation, with over a
100N perceived stiffness.
CoVR’s key feature is to enable whole-body interactions with large kinaesthetic feedback.
These are even stronger whenever we take advantage of CoVR’s displacements.
We conducted a user evaluation for usability purposes and to find out the favourite interactions.
In terms of usability, we did not have any unwanted collision with the user or mismatches
regarding their intentions.
Large-scale kinaesthetic feedback was appreciated.
Being transported and led through large traction forces were the favourite interactions, gathering
all the votes.
We presented CoVR, a novel robotic interface through its implementation and usability.
Results show that VR can indeed benefit from large force-feedback.
Thank you for watching this presentation.