Real-Time Numerical Simulation for Accurate Soft Tissues Modeling during Haptic Interaction

The simulation of fabrics physics and its interaction with the human body has been largely studied in recent years to provide realistic-looking garments and wears specifically in the entertainment business. When the purpose of the simulation is to obtain scientific measures and detailed mechanical properties of the interaction, the underlying physical models should be enhanced to obtain better simulation accuracy increasing the modeling complexity and relaxing the simulation timing constraints to properly solve the set of equations under analysis. However, in the specific field of haptic interaction, the desiderata are to have both physical consistency and high frame rate to display stable and coherent stimuli as feedback to the user requiring a tradeoff between accuracy and real-time interaction. This work introduces a haptic system for the evaluation of the fabric hand of specific garments either existing or yet to be produced in a virtual reality simulation. The modeling is based on the co-rotational Finite Element approach that allows for large displacements but the small deformation of the elements. The proposed system can be beneficial for the fabrics industry both in the design phase or in the presentation phase, where a virtual fabric portfolio can be shown to customers around the world. Results exhibit the feasibility of high-frequency real-time simulation for haptic interaction with virtual garments employing realistic mechanical properties of the fabric materials.

Leaders are made: Learning acquisition of consistent leader-follower relationships depends on implicit haptic interactions.

Are leaders made or born? Leader-follower roles have been well characterized in social science, but they remain somewhat obscure in sensory-motor coordination. Furthermore, it is unknown how and why leader-follower relationships are acquired, including innate versus acquired controversies. We developed a novel asymmetrical coordination task in which two participants (dyad) need to collaborate in transporting a simulated beam while maintaining its horizontal attitude. This experimental paradigm was implemented by twin robotic manipulanda, simulated beam dynamics, haptic interactions, and a projection screen. Clear leader-follower relationships were learned despite participants not being informed that they were interacting with each other, but only when strong haptic feedback was introduced. For the first time, we demonstrate the emergence of consistent leader-follower relationships in sensory-motor coordination, and further show that haptic interaction is essential for dyadic co-adaptation. These results provide insights into neural mechanisms responsible for the formation of leader-follower relationships in our society.

Single-master/multi-slave haptic teleoperation: a force control scheme

Purpose This paper aims to present a novel modular design framework for the haptic teleoperation of single-master/multiple-slave (SM/MS) systems with cooperating manipulators. Design/methodology/approach The user commands the remote-leader robot and the slave remote robot follows the leader in a leader–follower formation. The remote-slave is purely force-controlled. A virtual model of the remote environment is introduced between the local and remote environments through simulation software. Locally generated motion inputs are transmitted to the remote environment through the virtual model. A haptic coupling is designed in the virtual environment and the haptic feedback is transmitted to the user along with the forces measured in the remote environment. The controllers proposed in this work are experimentally evaluated with experienced and inexperienced users. Findings The proposed haptic interaction model contributes to the total force feedback and smoothens the high-frequency signals occurring at the physical interaction in the remote environment. Experimental results show that the implemented controllers including the proposed haptic interaction improve the teleoperation performances in terms of trajectory tracking. Furthermore, pure force control of the remote-slave is shown to enhance the robustness of the teleoperation against external disturbances. Satisfactory teleoperation performances are observed with both experienced and inexperienced users. Originality/value The proposed SM/MS teleoperation system involves a multi-purpose virtual simulator and a purely force-controlled remote-slave manipulator in a modular cooperative configuration. The uniquely defined structure of the proposed haptic coupling is used in modeling the interaction between the local and remote manipulators on the one hand, and between cooperating remote manipulators on the other.

Sense of Resistance for a Cursor Moved by User’s Keystrokes

Haptic sensation of a material can be modulated by its visual appearance. A technique that utilizes this visual-haptic interaction is called as pseudo-haptic feedback. Conventional studies have investigated pseudo-haptic feedback in situations, wherein a user manipulated a virtual object using a computer mouse, a force-feedback device, etc. The present study investigated whether and how it was possible to offer pseudo-haptic feedback to a user who manipulated a virtual object using keystrokes. Participants moved a cursor toward a destination by pressing a key. While the cursor was moving, the cursor was temporarily slowed down on a square area of the screen. The participants’ task was to report, on a five-point scale, how much resistance they felt to the cursor’s movement. In addition to the basic speed of the cursor, the ratio of the basic speed to the speed within the square area was varied. In Experiment 1, we found that these two factors interacted significantly with each other, but further analysis showed that the cursor speed within the square area was the most important determinant of perceived resistance. In Experiment 2, consistent with the results of the previous experiment, it was found that the cursor movement outside of the square area was not required to generate the sense of resistance. Counterintuitively, in Experiment 3, the sense of resistance was apparent even without user’s keystrokes. We discuss how the sense of resistance for a cursor moved by keystrokes can be triggered visually, but interpreted by the brain as a haptic impression.

Bi-manual Haptic-based Periodontal Simulation with Finger Support and Vibrotactile Feedback

The rise of virtual reality and haptic technologies has created exciting new applications in medical training and education. In a dental simulation, haptic technology can create the illusion of substances (teeth, gingiva, bone, etc.) by providing interaction forces within a simulated virtual world of the mouth. In this article, a haptic periodontal training simulation system, named Haptodont, is developed and evaluated for simulating periodontal probing. Thirty-two faculty members from New York University College of Dentistry were recruited and divided into three groups to evaluate three fundamental functionalities: Group 1 evaluated bi-manual 3 Degrees of Freedome (DoF) haptic interaction, Group 2 evaluated bi-manual 3 DoF haptic interaction with a finger support mechanism, and Group 3 evaluated bi-manual 3 DoF haptic interaction with finger support mechanism and vibrotactile feedback. The probe and mirror interactions were simulated with the Geomagic Touch haptic device whereas the finger support was implemented using the Novint Falcon device. The three groups conducted two probing tasks: healthy gingiva scenario with no pockets (2- to 3-mm depth) and periodontitis scenario with deep pockets (4- to 8-mm depth). Results demonstrated that experts performed comparably to clinical settings in terms of probing depth error (within 0.3 to 0.6 mm) and probing forces (less than 0.5 N). Furthermore, the finger support mechanism significantly improved the probing accuracy for periodontitis condition in the lingual region. The argument that probing the lingual region is more difficult than the buccal region is supported by quantitative evidence (significantly higher probing depth error and probing force). Further research is planned to improve the usability of the finger support, integrate the Haptodont system into the pre-clinical curriculum, and evaluate the Haptodont system with dental students as a learning tool.

Sense of resistance for a cursor moved by user’s keystrokes

Haptic sensation of a material can be modulated by its visual appearance. A technique that utilizes this visual-haptic interaction is called pseudo-haptic feedback. Conventional studies have investigated pseudo-haptic feedback in situations wherein a user manipulated a virtual object using a computer mouse, a force-feedback device, etc. The present study investigated whether and how it was possible to offer pseudo-haptic feedback to a user who manipulated a virtual object using keystrokes. Participants moved a cursor toward a destination by pressing a key. While the cursor was moving, the cursor was temporarily slowed down on a square area of the screen. The participants' task was to report, on a 5-point scale, how much resistance they felt to the cursor's movement. In addition to the basic speed of the cursor, the ratio of the basic speed to the speed within the square area was varied. In Experiment 1, we found that these two factors interacted significantly with each other, but further analysis showed that the cursor speed within the square area was the most important determinant of perceived resistance. In Experiment 2, consistent with the results of the previous experiment, it was found that the cursor movement outside of the square area was not required to generate the sense of resistance. Counterintuitively, in Experiment 3, the sense of resistance was apparent even without user's keystrokes. We discuss how the sense of resistance for a cursor moved by keystrokes can be triggered visually, but interpreted by the brain as a haptic impression.

StARboard & TrACTOr: Actuated Tangibles in an Educational TAR Application

We explore the potential of direct haptic interaction in a novel approach to Tangible Augmented Reality in an educational context. Employing our prototyping platform ACTO, we developed a tabletop Augmented Reality application StARboard for sailing students. In this personal viewpoint environment virtual objects, e.g., sailing ships, are physically represented by actuated micro robots. These align with virtual objects, allowing direct physical interaction with the scene. When a user tries to pick up a virtual ship, its physical robot counterpart is grabbed instead. We also developed a tracking solution TrACTOr, employing a depth sensor to allow tracking independent of the table surface. In this paper we present concept and development of StARboard and TrACTOr. We report results of our user study with 18 participants using our prototype. They show that direct haptic interaction in tabletop AR scores en-par with traditional mouse interaction on a desktop setup in usability (mean SUS = 86.7 vs. 82.9) and performance (mean RTLX = 15.0 vs. 14.8), while outperforming the mouse in factors related to learning like presence (mean 6.0 vs 3.1) and absorption (mean 5.4 vs. 4.2). It was also rated the most fun (13× vs. 0×) and most suitable for learning (9× vs. 4×).