Miniaturization of mechanical actuators in skin-integrated electronics for haptic interfaces

Skin-integrated electronics, also known as electronic skin (e-skin), are rapidly developing and are gradually being adopted in biomedical fields as well as in our daily lives. E-skin capable of providing sensitive and high-resolution tactile sensations and haptic feedback to the human body would open a new e-skin paradigm for closed-loop human–machine interfaces. Here, we report a class of materials and mechanical designs for the miniaturization of mechanical actuators and strategies for their integration into thin, soft e-skin for haptic interfaces. The mechanical actuators exhibit small dimensions of 5 mm diameter and 1.45 mm thickness and work in an electromagnetically driven vibrotactile mode with resonance frequency overlapping the most sensitive frequency of human skin. Nine mini actuators can be integrated simultaneously in a small area of 2 cm × 2 cm to form a 3 × 3 haptic feedback array, which is small and compact enough to mount on a thumb tip. Furthermore, the thin, soft haptic interface exhibits good mechanical properties that work properly during stretching, bending, and twisting and therefore can conformally fit onto various parts of the human body to afford programmable tactile enhancement and Braille recognition with an accuracy rate over 85%.

Emotional Response to Vibrothermal Stimuli

Emotional response to haptic stimuli is a widely researched topic, but the combination of vibrotactile and thermal stimuli requires more attention. The purpose of this study is to investigate emotional response to vibrothermal stimulation by combining spatiotemporal vibrotactile stimulus with dynamic thermal stimulus (hot or cold). The vibrotactile and thermal stimuli were produced using the Haptic Chair and the Embr wave thermal bracelet, respectively. The results show that spatiotemporal vibrotactile patterns and their duration, and dynamic thermal stimulation, have an independent effect on the emotional response. Increasing duration generally increases the valence and arousal of emotional response. Shifting the dynamic temperature from cold to hot generally decreases the valence of emotional response but has no significant effect on arousal. Nevertheless, certain spatiotemporal patterns do exhibit unique responses to changes in dynamic temperature, although no interaction effects were found. The results show the potential of designing affective haptic interfaces using multimodal vibrothermal feedback.

Safe Collaboration Between Human and Robot in a Context of Intermittent Haptique Interface

In the list of interfaces used to make virtual reality, haptic interfaces allow users to touch a virtual world with their hands. Traditionally, the user’s hand touches the end effector of a robotic arm. When there is no contact, the robotic arm is passive; when there is contact, the arm suppresses mobility to the user’s hand in certain directions. Unfortunately, the passive mode is never completely seamless to the user. Haptic interfaces with intermittent contacts are interfaces using industrial robots that move towards the user when contact needs to be made. As the user is immersed via a virtual reality Head Mounted Display (HMD), he cannot perceive the danger of a collision when he changes his area of interest in the virtual environment. The objective of this article is to describe movement strategies for the robot to be as fast as possible on the contact zone while guaranteeing safety. This work uses the concept of predicting the position of the user through his gaze direction and the position of his dominant hand (the one touching the object). A motion generation algorithm is proposed and then applied to a UR5 robot with an HTC vive tracker system for an industrial application involving the analysis of materials in the interior of a car.

Contact-initiated shared control strategies for four-arm supernumerary manipulation with foot interfaces

In industrial or surgical settings, to achieve many tasks successfully, at least two people are needed. To this end, robotic assistance could be used to enable a single person to perform such tasks alone, with the help of robots through direct, shared, or autonomous control. We are interested in four-arm manipulation scenarios, where both feet are used to control two robotic arms via bi-pedal haptic interfaces. The robotic arms complement the tasks of the biological arms, for instance, in supporting and moving an object while working on it (using both hands). To reduce fatigue, cognitive workload, and to ease the execution of the foot manipulation, we propose two types of assistance that can be enabled upon contact with the object (i.e., based on the interaction forces): autonomous-contact force generation and auto-coordination of the robotic arms. The latter relates to controlling both arms with a single foot, once the object is grasped. We designed four (shared) control strategies that are derived from the combinations (absence/presence) of both assistance modalities, and we compared them through a user study (with 12 participants) on a four-arm manipulation task. The results show that force assistance positively improves human–robot fluency in the four-arm task, the ease of use and usefulness; it also reduces the fatigue. Finally, to make the dual-assistance approach the preferred and most successful among the proposed control strategies, delegating the grasping force to the robotic arms is a crucial factor when controlling them both with a single foot.

A New Strategy for Multi- Objective Dynamic and Kinematic Optimization of Robotic Manipulators with Application in Haptic Interfaces

There is an increasing demand for higher performance in modern robotic applications. To meet the need for more accuracy and fast dynamic response, considering inertial effects is necessary. This thesis proposes a new global multi-objective optimization strategy to tune the geometric and dynamic capabilities of a manipulator. Then, as a case study, the kinematics and dynamic behavior of a five-bar-linkage haptic interface is analyzed and a new design procedure is obtained using a new global and constrained multi-objective technique. The minimax culling algorithm was used to design parameters for optimal kinematics and dynamic dexterity measure.

A New Strategy for Multi- Objective Dynamic and Kinematic Optimization of Robotic Manipulators with Application in Haptic Interfaces

There is an increasing demand for higher performance in modern robotic applications. To meet the need for more accuracy and fast dynamic response, considering inertial effects is necessary. This thesis proposes a new global multi-objective optimization strategy to tune the geometric and dynamic capabilities of a manipulator. Then, as a case study, the kinematics and dynamic behavior of a five-bar-linkage haptic interface is analyzed and a new design procedure is obtained using a new global and constrained multi-objective technique. The minimax culling algorithm was used to design parameters for optimal kinematics and dynamic dexterity measure.