Team, Visitors, External Collaborators
Overall Objectives
Research Program
Highlights of the Year
New Software and Platforms
New Results
Bilateral Contracts and Grants with Industry
Partnerships and Cooperations
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Section: New Results

Shared Control Architectures

Shared Control for Remote Manipulation

Participants : Firas Abi Farraj, Paolo Robuffo Giordano, Claudio Pacchierotti, Rahaf Rahal.

As teleoperation systems become more sophisticated and flexible, the environments and applications where they can be employed become less structured and predictable. This desirable evolution toward more challenging robotic tasks requires an increasing degree of training, skills, and concentration from the human operator. For this reason, researchers started to devise innovative approaches to make the control of such systems more effective and intuitive. In this respect, shared control algorithms have been investigated as one the main tools to design complex but intuitive robotic teleoperation system, helping operators in carrying out several increasingly difficult robotic applications, such as assisted vehicle navigation, surgical robotics, brain-computer interface manipulation, rehabilitation. This approach makes it possible to share the available degrees of freedom of the robotic system between the operator and an autonomous controller. The human operator is in charge of imparting high level, intuitive goals to the robotic system; while the autonomous controller translates them into inputs the robotic system can understand. How to implement such division of roles between the human operator and the autonomous controller highly depends on the task, robotic system, and application. Haptic feedback and guidance have been shown to play a significant and promising role in shared control applications. For example, haptic cues can provide the user with information about what the autonomous controller is doing or is planning to do; or haptic force can be used to gradually limit the degrees of freedom available to the human operator, according to the difficulty of the task or the experience of the user. The dynamic nature of haptic guidance enables us to design very flexible robotic system, which can easily and rapidly change the division of roles between the user and autonomous controller.

Along this general line of research, during this year we gave the following contributions:

Teleoperation of Flexible Needle with Haptic Feedback and Ultrasound Guidance

Participants : Jason Chevrie, Alexandre Krupa, Marie Babel.

Needle insertion procedures under ultrasound guidance are commonly used for diagnosis and therapy. This kind of intervention can greatly benefit from robotic systems to improve their accuracy and success rate. In the past years, we have developed a robotic framework dedicated to 3D steering of beveled-tip flexible needle in order to autonomously reach a desired target in the tissues by ultrasound visual servoing using a 3D ultrasound probe. This year we have proposed a real-time semi-automatic teleoperation framework that enables the user to directly control the trajectory of the needle tip during its insertion via a haptic interface [38]. The framework enables the user to intuitively guide the trajectory of the needle tip in the ultrasound 3D volume while the controller handles the complexity of the 6D motion that needs to be applied to the needle base. A mean targeting accuracy of 2.5 mm has been achieved in gelatin phantoms and different ways to provide the haptic feedback as well as different levels of control given to the user on the tip trajectory have been compared. Limiting the user input to the insertion speed while automatically controlling the trajectory of the needle tip seems to provide a safer insertion process, however it may be too constraining and can not handle situations where more control over the tip trajectory is required, for example if unpredicted obstacles need to be avoided. On the contrary, giving the full control of the 3D tip velocity to the user and applying a haptic feedback to guide the user toward the target proved to maintain a low level of needle bending and tissue deformation.

Needle Comanipulation with Haptic Guidance

Participants : Hadrien Gurnel, Alexandre Krupa.

The objective of this work is to provide assistance during manual needle steering for biopsies or therapy purposes (see Section 7.2.3). At the difference of our work presented in Section 6.4.2 where a robotic system is used to steer the needle, we propose in this study another way of assistance where the needle is collaboratively manipulated by the physician and a haptic device. The principle of our approach is to provide haptic cue feedback to the clinician in order to help him during his manual gesture [43]. We elaborated 5 different haptic-guidance strategies to assist the needle pre-positioning and pre-orienting on a pre-defined insertion point, and with a pre-planned desired incidence angle. The haptic guides rely on the position and orientation errors between the needle, the entry point and the desired angle of incidence toward the target, which are computed from the measurements provided by an electromagnetic tracker. Each of the guide implements a different Guiding Virtual Fixture producing haptic cues that attract the needle towards a point or a trajectory in space with different force feedback applied on the user's hand manipulating the needle. A two-step evaluation was conducted to assess the performance and ergonomy of each haptic guide, and compare them to the unassisted reference gesture. The first evaluation stage [44] involved two physicians both experts in needle manipulation at Rennes University Hospital. The performance results showed that, compared to the unassisted gesture, the positioning accuracy was enhanced with haptic guidance. The second evaluation stage [43] was a user study with twelve participants. From this second study it results that the most constraining guide allows to perform the gesture with the best accuracy, lower time duration and highest level of ergonomy.

Shared Control of a Wheelchair for Navigation Assistance

Participants : Louise Devigne, Marie Babel.

Power wheelchairs allow people with motor disabilities to have more mobility and independence. However, driving safely such a vehicle is a daily challenge particularly in urban environments while navigating on sidewalks, negotiating curbs or dealing with uneven grounds. Indeed, differences of elevation have been reported to be one of the most challenging environmental barrier to negotiate, with tipping and falling being the most common accidents power wheelchair users encounter. It is thus our challenge to design assistive solutions for power wheelchair navigation in order to improve safety while navigating in such environments. To this aim, we proposed a shared-control algorithm which provides assistance while navigating with a wheelchair in an environment consisting of negative obstacles. We designed a dedicated sensor-based control law allowing trajectory correction while approaching negative obstacles e.g. steps, curbs, descending slopes. This shared control method takes into account the humanin-the loop factor. In this study, our solution the ability of our system to ensure a safe trajectory while navigating on a sidewalk is demonstrated through simulation, thus providing a proof-of-concept of our method [42].

Wheelchair-Human Interactions during crossing situations

Participants : Marie Babel, Julien Pettré.

Designing smart powered wheelchairs requires to better understand interactions between walkers and such vehicles. We focus on collision avoidance task between a power wheelchair (fully operated by a human) and a walker, where the difference in the nature of the agents (weight, maximal speed, acceleration profiles) results into asymmetrical physical risk in case of a collision, for example due to the protection power wheelchair provides to its driver, or the higher energy transferred to the walker during head-on collision.

We then conducted experiments with Results show that walkers set more conservative strategies when interacting with a power wheelchair. These results can then be linked to the difference in the physical characteristics of the walkers and power wheelchairs where asymmetry in the physical risks raised by collisions influence the strategies performed by the walkers in comparison with a similar walker-walker situation. This gives interesting insights in the task of modeling such interactions, indicating that geometrical terms are not sufficient to explain behaviours, physical terms linked to collision momentum should also be considered [49][62].

Multisensory power wheelchair simulator

Participants : Guillaume Vailland, Louise Devigne, François Pasteau, Marie Babel.

Power wheelchair driving is a challenging task which requires good visual, cognitive and visuo-spatial abilities. Besides, a power wheelchair can cause material damage or represent a danger of injury for others or oneself if not operated safely. Therefore, training and repeated practice are mandatory to acquire safe driving skills to obtain power wheelchair prescription from therapists. However, conventional training programs may reveal themselves insufficient for some people with severe impairments. In this context, Virtual Reality offers the opportunity to design innovative learning and training programs while providing realistic wheelchair driving experience within a virtual environment. We then proposed a user-centered design of a multisensory power wheelchair simulator [59][58]. This simulator addresses classical virtual experience drawbacks such as cybersickness and sense of presence by combining 3D visual rendering, haptic and vestibular feedback. It relies on a modular and versatile workflow enabling not only easy interfacing with any virtual display, but also with any user interface such as wheelchair controllers or feedback devices. First experiments with able-bodied people shown that vestibular feedback activation increases the Sense of Presence and decreases cybersickness [54].