Section: New Results

Haptic Cueing for Robotic Applications

The objective of this work is to provide assistance during manual needle steering for biopsies or therapy purposes (see Section 9.1.6). At the difference of our work presented in Section 7.2.9 where a robotic system is used to autonomously actuate the needle, we propose in this study another way of assistance for needle insertion. The principle is to provide haptic cue feedback to the clinician in order to help him during his manual gesture by the application of repulsive or attractive forces. The proposed solution is based on a shared robotic control, where the clinician and a haptic device, both holding the base of the needle, cooperate together. In a preliminary study, 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. From this pre-operative information and intra-operative measurements of the location of the needle, haptic cues are generated to guide the clinician toward the desired needle position and orientation. These 5 different haptic guides were recently tested by 2 physicians, both experts in needle manipulation and compared to the reference gesture performed without assistance. The results have been submitted to the IPCAI 2019 conference. Future work will consist in evaluating the different haptic guides from an user-experience study involving more participants.

We worked on a wearable haptic device for the forearm and its application in robotic teleoperation [8]. The device is able to provide skin stretch, pressure, and vibrotactile stimul, see Fig. 10. Two servo motors, housed in a 3D printed lightweight platform, actuate an elastic fabric belt, wrapped around the arm. When the two servo motors rotate in opposite directions, the belt is tightened (or loosened), thereby compressing (or decompressing) the arm. On the other hand, when the two motors rotate in the same direction, the belt applies a shear force to the arm skin. Moreover, the belt houses four vibrotactile motors, positioned evenly around the arm at 90 degrees from each other. The device weights 220 g for 115$\times$122$\times$50 mm of dimensions, making it wearable and unobtrusive. We carried out a perceptual characterization of the device as well as two human-subjects teleoperation experiments in a virtual environment, employing a total of 34 subjects.

Figure 10. The proposed wearable device for the arm and its evaluation. The device consists of a static platform (A) that accommodates two servomotors (B) and two pulleys (C), a fabric belt (D), and four vibrotactile motors (E).

In the first experiment, participants were asked to control the motion of a robotic manipulator for grasping an object; in the second experiment, participants were asked to teleoperate the motion of a quadrotor fleet along a given path. In both scenarios, the wearable haptic device provided feedback information about the status of the slave robot(s) and of the given task. Results showed the effectiveness of the proposed device. Performance on completion time, length trajectory, and perceived effectiveness when using the wearable device improved of 19.8%, 25.1%, and 149.1% than when wearing no device, respectively. Finally, all subjects but three preferred the conditions including wearable haptics.

Robotic telemanipulators are already widely used in nuclear decommissioning sites for handling radioactive waste. However, currently employed systems are still extremely primitive, making the handling of these materials prohibitively slow and ineffective. As the estimated cost for the decommissioning and clean-up of nuclear sites keeps rising, it is clear that one would need faster and more effective approaches. Towards this goal, we presented the user evaluation of a recently proposed haptic-enabled shared-control architecture for telemanipulation [51]. An autonomous algorithm regulates a subset of the slave manipulator degrees of freedom (DoF) in order to help the human operator in grasping an object of interest. The human operator can then steer the manipulator along the remaining null-space directions with respect to the main task by acting on a grounded haptic interface. The haptic cues provided to the operator are designed in order to inform about the feasibility of the user's commands with respect to possible constraints of the robotic system. This work compared this shared-control architecture against a classical 6-DOF teleoperation approach in a real scenario by running experiments with 10 subjects. The results clearly show that the proposed shared-control approach is a viable and effective solution for improving currently-available teleoperation systems in remote telemanipulation tasks.

Smart powered wheelchairs can increase mobility and independence for people with disability by providing navigation support. For rehabilitation or learning purposes, it would be of great benefit for wheelchair users to have a better understanding of the surrounding environment while driving. Therefore, a way of providing navigation support is to communicate information through a dedicated and adapted feedback interface. We have then proposed a framework in which feedback is provided by sending forces through the wheelchair controller as the user steers the wheelchair. This solution is based on a low complex optimization framework able to perform smooth trajectory correction and to provide obstacle avoidance. The impact of the proposed haptic guidance solution on user driving performance was assessed during this pilot study for validation purposes through an experiment with 4 able-bodied participants. Results of this pilot study showed that the number of collisions significantly decreased while force feedback was activated, thus validating the proposed framework [60].