Transparency in Human-Machine Mutual Action

Recent advances in human-computer integration (HInt) have focused on the development of human-machine systems, where both human and machine autonomously act upon each other. However, a key challenge in designing such systems is augmenting the user’s physical abilities while maintaining their sense of self-attribution. This challenge is particularly prevalent when both human and machine are capable of acting upon each other, thereby creating a human-machine mutual action (HMMA) system. To address this challenge, we present a design framework that is based on the concept of transparency. We define transparency in HInt as the degree to which users can self-attribute an experience when machines intervene in the users’ action. Using this framework, we form a set of design guidelines and an approach for designing HMMA systems. By using transparency as our focus, we aim to provide a design approach for not only achieving human-machine fusion into a single agent, but also controlling the degrees of fusion at will. This study also highlights the effectiveness of our design approach through an analysis of existing studies that developed HMMA systems. Further development of our design approach is discussed, and future prospects for HInt and HMMA system designs are presented.

A review of haptic feedback in tele-operated robotic surgery

During traditional surgery, the surgeons' hands are in direct contact with organs, and surgeons rely on the sense of touch to perform surgery. In teleoperated robotic systems, all physical connections between the surgeon and both the robot and patient, are absent. The surgeon must estimate the force exerted on organs, based only on visual deformation of tissues he is pulling, pushing, gripping, or suturing. It is hard to imagine how to operate with no haptic sensations, and it is surprising that commercially available robots didn't include until now any Haptic Feedback, despite reports about tissue injury, and inability to perform complex manipulation. The sense of touch must be created by stimuli sensed by the surgeon. Haptic sensors are required to collect and send haptic information, and display them on the operator's side, creating telepresence, known as transparency. Multiple ways have been developed to improve transparency through force feedback and tactile feedback. However, this interferes with the stability of the closed-loop controlling interactions between master, robot and remote environment. Cutaneous feedback is more stable and less transparent; force feedback is more transparent and less stable. Thus, multimodal platforms of haptic feedback would try to find the best trade-off between both modalities.

Characterizing and Imaging Gross and Real Finger Contacts under Dynamic Loading

We describe an instrument intended to study finger contacts under tangential dynamic loading. This type of loading is relevant to the natural conditions when touch is used to discriminate and identify the properties of the surfaces of objects-it is also crucial during object manipulation. The system comprises a high performance tribometer able to accurately record in vivo the components of the interfacial forces when a finger interacts with arbitrary surfaces which is combined with a high-speed, high-definition imaging apparatus. Broadband skin excitation reproducing the dynamic contact loads previously identified can be effected while imaging the contact through a transparent window, thus closely approximating the condition when the skin interacts with a non-transparent surface during sliding. As a preliminary example of the type of phenomenon that can be identified with this apparatus, we show that traction in the range from 10 to 1000 Hz tends to decrease faster with excitation frequency for dry fingers than for moist fingers.

KiloHertz Bandwidth, Dual-Stage Haptic Device Lets You Touch Brownian Motion

This paper describes a haptic interface that has a uniform response over the entire human tactile frequency range. Structural mechanics makes it very difficult to implement articulated mechanical systems that can transmit high frequency signals. Here, we separated the frequency range into two frequency bands. The lower band is within the first structural mode of the corresponding haptic device while the higher one can be transmitted accurately by a fast actuator operating from conservation of momentum, that is, without reaction forces to the ground. To couple the two systems, we adopted a channel separation approach akin to that employed in the design of acoustic reproduction systems. The two channels are recombined at the tip of the device to give a uniform frequency response from DC to one kHz. In terms of mechanical design, the high-frequency transducer was embedded inside the tip of the main stage so that during operation, the human operator has only to interact with a single finger interface. In order to exemplify the type of application that would benefit from this kind of interface, we applied it to the haptic exploration with microscopic scales objects which are known to behave with very fast dynamics. The novel haptic interface was bilaterally coupled with a micromanipulation platform to demonstrate its capabilities. Operators could feel interaction forces arising from contact as well as those resulting from Brownian motion and could manoeuvre a micro bead in the absence of vision.

Feeling what an insect feels

We describe a manually operated, bilateral mechanical scaling instrument that simultaneously magnifies microscopic forces and reduces displacements with quasi-perfect transparency. In contrast with existing micro-teleoperation designs, the system is unconditionally stable for any scaling gains and interaction curves. In the present realization, the work done by the hand is more than a million times that done by a microscopic probe so that one can feel complete interaction cycles with water and compare them to what is felt when an insect leg interacts with a wet surface.

Design and control of a dual unidirectional brake hybrid actuation system for haptic devices

Hybrid actuators combining brakes and motors have emerged as an efficient solution to achieve high performance in haptic devices. In this paper, an actuation approach using two unidirectional brakes and a DC motor is proposed. The brakes are coupled to overrunning clutches and can apply a torque in only one rotational direction. The associated control laws, that are independent of the virtual environment model, calculate the control gains in real time in order limit the energy and the stiffness delivered by the motor to ensure stability. The reference torque is respected using the combination of the motor and the brake. Finally, an user experiment has been performed to evaluate the influence of passive and active torque differences in the perception of elasticity. The proposed actuator has a torque range of 0.03 Nm to 5.5 Nm with a 17.75 kNm (-2) torque density.

Invited article: a review of haptic optical tweezers for an interactive microworld exploration

This paper is the first review of haptic optical tweezers, a new technique which associates force feedback teleoperation with optical tweezers. This technique allows users to explore the microworld by sensing and exerting picoNewton-scale forces with trapped microspheres. Haptic optical tweezers also allow improved dexterity of micromanipulation and micro-assembly. One of the challenges of this technique is to sense and magnify picoNewton-scale forces by a factor of 10(12) to enable human operators to perceive interactions that they have never experienced before, such as adhesion phenomena, extremely low inertia, and high frequency dynamics of extremely small objects. The design of optical tweezers for high quality haptic feedback is challenging, given the requirements for very high sensitivity and dynamic stability. The concept, design process, and specification of optical tweezers reviewed here are focused on those intended for haptic teleoperation. In this paper, two new specific designs as well as the current state-of-the-art are presented. Moreover, the remaining important issues are identified for further developments. The initial results obtained are promising and demonstrate that optical tweezers have a significant potential for haptic exploration of the microworld. Haptic optical tweezers will become an invaluable tool for force feedback micromanipulation of biological samples and nano- and micro-assembly parts.

Differential-damper topologies for actuators in rehabilitation robotics

Differential-damper (DD) elements can provide a high bandwidth means for decoupling a high inertia, high friction, non-backdrivable actuator from its output and can enable high fidelity force control. In this paper, a port-based decomposition is used to analyze the energetic behavior of such actuators in various physical domains. The general concepts are then applied to a prototype DD actuator for illustration and discussion. It is shown that, within physical bounds, the output torque from a DD actuator can be controlled independently from the input speed. This concept holds the potential to be scaled up and integrated in a compact and lightweight package powerful enough for incorporation with a portable lower limb orthotic or prosthetic device.