Michael Peshkin

Northwestern University | NU · Department of Mechanical Engineering

The ability to render realistic texture perception using haptic devices has been consistently challenging. A key component of texture perception is roughness. When we touch surfaces, mechanoreceptors present under the skin are activated and the information is processed by the nervous system, enabling perception of roughness/smoothness. Several dist...

As the number of applications for tactile feedback technology rapidly increases, so too does the need for efficient, flexible, and extensible representations of virtual textures. The previously-introduced Single-Pitch Texel rendering algorithm offers designers the ability to produce textures with perceptually wide-band spectral characteristics whil...

A “cobot” is a robotic device which manipulates objects in collaboration with a human operator. A cobot provides assistance to the human operator by setting up virtual surfaces which can be used to constrain and guide motion. While conventional servo-actuated haptic displays may be used in this way also, an important distinction is that, while hapt...

We present PixeLite, a novel haptic device that produces distributed lateral forces on the fingerpad. PixeLite is 0.15 mm thick, weighs 1.00 g, and consists of a 4×4 array of electroadhesive brakes (“pucks”) that are each 1.5 mm in diameter and spaced 2.5 mm apart. The array is worn on the fingertip and slid across an electrically grounded counters...

This paper introduces a novel rendering algorithm for virtual textures, specifically those with characteristic length scales below 1 mm. By leveraging the relatively lossy mode of human tactile perception at this length scale, a virtual texture with wide-band spectral characteristics can be reduced to a spatial sequence of single-frequency texels...

Friction modulation technology enables the creation of textural effects on flat haptic displays. However, an intuitive and manageably small design space for construction of such haptic textures remains an unfulfilled goal for user interface designers. In this paper, we explore perceptually relevant features of fine texture for use in texture constr...

This study seeks to understand conditions under which virtual gratings produced via vibrotaction and friction modulation are perceived as similar and to find physical origins in the results. To accomplish this, we developed two single-axis devices, one based on electroadhesion and one based on out-of-plane vibration. The two devices had identical t...

This study seeks to understand conditions under which virtual gratings produced via vibrotaction and friction modulation are perceived as similar and to find physical origins in the results. To accomplish this, we developed two single-axis devices, one based on electroadhesion and one based on out-of-plane vibration. The two devices had identical t...

We present a new device, the SwitchPaD, to generate an active lateral force on a bare fingertip over a large touch area. Like our previous device, the UltraShiver, the SwitchPaD uses synchronization of in-plane ultrasonic oscillation and out-of-plane electroadhesion to generate force. The UltraShiver, however, relied on a single longitudinal resona...

One well-known class of surface haptic devices that we have called TPaDs (Tactile Pattern Displays) uses ultrasonic transverse vibrations of a touch surface to modulate fingertip friction. This paper addresses the power consumption of glass TPaDs, which is an important consideration in the context of mobile touchscreens. In particular, based on exi...

Friction modulation technology enables the creation of textural effects on flat haptic displays. However, an intuitive and manageably small design space for construction of such haptic textures remains an unfulfilled goal for user interface designers. In this paper, we explore perceptually relevant features of fine texture for use in texture constr...

We have developed a novel button click rendering mechanism based on active lateral force feedback. The effect can be localized because electroadhesion between a finger and a surface can be localized. Psychophysical experiments were conducted to evaluate the quality of a rendered button click, which subjects judged to be acceptable. Both the experim...

We have developed a novel button click rendering mechanism based on active lateral force feedback. The effect can be localized because electroadhesion between a finger and a surface can be localized. Psychophysical experiments were conducted to evaluate the quality of a rendered button click, which subjects judged to be acceptable. Both the experim...

One well-known class of surface haptic devices that we have called TPaDs (Tactile Pattern Displays) uses ultrasonic transverse vibrations of a touch surface to modulate fingertip friction. This paper addresses the power consumption of glass TPaDs, which is an important consideration in the context of mobile touchscreens. In particular, based on exi...

We propose a new lateral force feedback device, the UltraShiver, which employs a combination of in-plane ultrasonic oscillation (around 30 kHz) and out-of-plane electroadhesion. It can achieve a strong active lateral force (400 mN) on the bare fingertip while operating silently. The lateral force is a function of pressing force, lateral vibration v...

Human perception of surface stickiness is closely related to intermittent slip dynamics, or stiction. In this work, we develop a method for real-time closed-loop rendering of surface stiction on an electroadhesive surface haptic display, and test it on a custom-built tribometer. We perform a psychophysical study to determine the effectiveness of a...

We report on the characterization of two variable friction electroadhesive displays using careful electrical and electrochemical impedance measurements. We qualitatively and quantitatively examine the properties of the skin, body, surface coating, and various electrode interface impedances in isolation using different contact interface conditions a...

We report an electroadhesive approach to controlling friction forces on sliding fingertips which is capable of producing vibrations across an exceedingly broad range of tactile, audible, and ultrasonic frequencies. Vibrations on the skin can be felt directly, and vibrations in the air can be heard emanating from the finger. Additionally, we report...

Active electrosense is a non-visual, short range sensing system used by weakly electric fish, enabling such fish to locate and identify objects in total darkness. Here we report initial findings from the use of active electrosense for object localization during underwater teleoperation with a virtual reality (VR) head-mounted display (HMD). The adv...

We describe a new haptic force feedback device capable of creating lateral shear force on a bare fingertip—the eShiver. The eShiver creates a net lateral force from in-plane oscillatory motion of a surface synchronized with a “friction switch” based on Johnsen-Rahbek electroadhesion. Using an artificial finger, a maximum net lateral force of $\pm$...

Weakly electric fish emit an AC electric field into the water and use thousands of sensors on the skin to detect field perturbations due to surrounding objects. The fish's active electrosensory system allows them to navigate and hunt, using separate neural pathways and receptors for resistive and capacitive perturbations. We have previously develop...

This paper presents two tooling-integrated sensing techniques for the in situ measurement and analyses of pressure distribution at the tool-workpiece interface and material drawin during the stamping processes. Specifically, the contact pressure distribution is calculated from the measurements by an array of force sensors embedded in the punch, whe...

The Gestalt theory of perception offered principles by which distributed visual sensations are combined into a structured experience ("Gestalt"). We demonstrate conditions whereby haptic sensations at two fingertips are integrated in the perception of a single object. When virtual bumps were presented simultaneously to the right hand's thumb and in...

This work aims to demonstrate and explain a nearly century old electrostatic haptic effect in human fingertips, which has since gone unreported. This effect, based on the original work of Johnsen and Rahbek [1], as well as research on electrostatic chucking devices [2], is capable of producing electrostatic forces on the finger an order of magnitud...

Active electrosense is used by some fish for the sensing of nearby objects by means of the perturbations the objects induce in a self-generated electric field. As with echolocation (sensing via perturbations of an emitted acoustic field) active electrosense is particularly useful in environments where darkness, clutter or turbidity makes vision ine...

Significance When multiple fingertips experience force sensations during movement, how does the brain decide whether to interpret the forces separately or as an integrated whole? To investigate this question, a force feedback device was used to display forces to two fingertips as they moved collinearly. The force patterns on each finger were constr...

Haptic interfaces controlled by a single fingertip or hand-held probe tend to display surface features individually, requiring serial search for multiple features. Novel surface haptic devices, however, have the potential to provide displays to multiple fingertips simultaneously, affording the possibility of parallel search. Using variable-friction...

A haptic device is provided having a substrate with a touch surface and one or more actuators for vibrating the substrate in a multiplicity of higher resonant modes, each of which has a high enough frequency to be inaudible and high enough amplitude to create a friction reduction effect at a plurality of vibrating regions on the substrate touch sur...

We present the design and evaluation of a high fidelity surface-haptic device. The user slides a finger along a glass plate while friction is controlled via the amplitude modulation of ultrasonic vibrations of the plate. A non-contact finger position sensor and low latency rendering scheme allow for the reproduction of fine textures directly on the...

The small size of touchscreen smart watches presents a unique interaction challenge. While the “fat-finger problem” is present on tablets and smartphones, it is exacerbated on smart watches, potentially occluding up to half of the display at a time. Haptic feedback can potentially be used to fill this information gap by aiding in location identific...

Surface haptic devices modulate the friction between the surface and the fingertip, and can thus be used to create a tactile perception of surface features or textures. We present modeling and experimental results on both ultrasonic and electrostatic surface haptic devices, characterizing their dynamics and their bandwidth for rendering haptic effe...

form only given. We present two surface haptic displays capable of rendering high-frequency textural content directly to the fingertip exploring the device. The friction of the fingertip with the glass plate is modulated either by electrostatic attraction or ultrasonic out-of-plane vibration. The unique rendering capabilities of these devices is po...

A TPad Tablet is a tablet computer with a variable friction touchscreen. It can create the perception of force, shape, and texture on a fingertip, enabling unique and novel haptic interactions on a flat touchscreen surface. We have created an affordable and easy to use variable friction device and have made it available through the open-hardware TP...

Background: The mechanical properties of human joints (i.e. impedance) are constantly modulated to precisely govern human interaction with the environment. The estimation of these properties requires the displacement of the joint from its intended motion and a subsequent analysis to determine the relationship between the imposed perturbation and th...

The human fingertip is extremely sensitive to lateral (shear) forces that arise in surface exploration. We and others have developed haptic displays that work by modulating surface friction via electrostatic attraction. Despite the demonstrated ability of these displays to render haptic environments, an understanding of the fingertip-surface interf...

This work investigates how haptic percepts are combined across two fingertips. Two single-degree-of-freedom haptic interfaces were used to present virtual bumps to the thumb and index finger of subjects' right hand. As subjects slid the two interfaces from left to right while maintaining a fixed finger separation, they would encounter one bump with...

Certain electric fish use a self-generated AC electric field to navigate and hunt. Thousands of sensors on the surface of the fish's body detect the pattern of amplitude and phase distortions of the field caused by nearby objects. Prior research has suggested that phase distortions may be especially useful for recognition of live objects. Here we p...

We present a new surface haptic interface that combines a variable friction device (the Large Area TPaD) with an impedance controlled planar mechanism. This device configuration is novel because it allows control of the frictional force in the static friction regime, control of the direction of force in the kinetic friction regime, as well as a deg...

The LateralPaD is a surface haptic device that generates lateral (shear) force on a bare finger, by vibrating the touch surface simultaneously in both out-of-plane (normal) and in-plane (lateral) directions. A prototype LateralPaD has been developed in which the touch surface is glass, and piezoelectric actuators drive normal and lateral resonances...

In fingertip interaction with a virtual surface, the illusion of a protruding bump can be created even in the absence of out-of-plane forces or motions, by presenting just the lateral forces associated with sliding over a bump [19]. We found that when a virtual bump on one side of a planar haptic display surface is explored with a fingertip, adding...

A new method of lower-limb exoskeleton control aimed at improving the agility of leg-swing motion is presented. In the absence of control, an exoskeleton's mechanism usually hinders agility by adding mechanical impedance to the legs. The uncompensated inertia of the exoskeleton will reduce the natural frequency of leg swing, probably leading to low...

This paper presents the design and simulation of a cyclic robot for lower-limb exercise robots. The robot is designed specifically for cyclic motions and the high power nature of lower-limb interaction-as such, it breaks from traditional robotics wisdom by intentionally traveling through singularities and incorporating large inertia. Such attribute...

In order to provide natural, biomimetic control to recently developed powered ankle prostheses, we must characterize the impedance of the ankle during ambulation tasks. To this end, a platform robot was developed that can apply an angular perturbation to the ankle during ambulation and simultaneously acquire ground reaction force data. In this stud...

Touch interactions occur through flat surfaces that lack the tactile richness of physical interfaces. We explore the design possibilities offered by augmenting touchscreens with programmable surface friction. Four exemplar applications -- an alarm clock, a file manager, a game, and a text editor -- demonstrate tactile effects that improve touch int...

Touch interactions have refreshed some of the 'glowing enthusiasm' of thirty years ago for direct manipulation interfaces. However, today's touch technologies, whose interactions are supported by graphics, sounds or crude clicks, have a tactile sameness and gaps in usability. We use a Large Area Tactile Pattern Display (LATPaD) to examine design po...

The quasistatic approximation to the motion of a mechanical system is the solution to Newton's law Ftotd = ma with m set to zero. In real systems m = 0 is never exact, but in many systems dissipative forces so overwhelm the inertial term mu that the quasistatic approximation is useful, even though neither mass

Limited research has been done on exoskeletons to enable faster movements of the lower extremities. An exoskeleton’s mechanism can actually hinder agility by adding weight, inertia and friction to the legs; compensating inertia through control is particularly difficult due to instability issues. The added inertia will reduce the natural frequency o...

Many of the current implementations of exoskeletons for the lower extremities are conceived to either augment the user's load-carrying capabilities or reduce muscle activation during walking. Comparatively little research has been conducted on enabling an exoskeleton to increase the agility of lower-limb movements. One obstacle in this regard is th...

Human-robot interfaces can be challenging and tiresome because of misalignments in the control and view relationships. The human user must mentally transform (e.g., rotate or translate) desired robot actions to required inputs at the interface. These mental transformations can increase task difficulty and decrease task performance. This chapter dis...

Existing prosthetic limbs do not provide amputees with cutaneous feedback. Tactile feedback is essential to intuitive control of a prosthetic limb and it is now clear that the sense of body self-identification is also linked to cutaneous touch. Here we have created an artificial sense of touch for a prosthetic limb by coupling a pressure sensor on...

Rich tactile interaction with control surfaces has been compromised in the transition to touch interfaces. This paper discusses new haptic effects that restore physicality to touch interaction by dynamically altering a touchscreen's frictional properties.

The lack of proprioceptive feedback is a serious deficiency of current prosthetic control systems. The Osseo-Magnetic Link (OML) is a novel humeral or wrist rotation control system that could preserve proprioception. It utilizes a magnet implanted within the residual bone and sensors mounted in the prosthetic socket to detect magnetic field vectors...

Stiff-knee gait is defined as reduced knee flexion during the swing phase. It is accompanied by frontal plane compensatory movements (eg, circumduction and hip hiking) typically thought to result from reduced toe clearance. As such, we examined if knee flexion assistance before foot-off would reduce exaggerated frontal plane movements in people wit...

We discuss the design and performance of a new haptic surface capable of controlling shear force on a bare finger. At the heart of the ShiverPaD is the TPaD variable friction device. It modulates the friction of a glass surface by using 39 kHz out-of-plane vibrations to reduce friction. To generate shear forces, the TPaD is oscillated in-plane (i.e...

We describe a variable friction haptic display on a large area of glass, and characterize its performance. The Large Area Tactile Pattern Display (LATPaD) uses modulation of surface friction created by ultrasonic vibration, as in previous smaller devices [8]. Unlike those, the LATPaD does not operate in the lowest resonant mode. As a consequence, t...

We have developed three different versions of a multifunction haptic device that can display touch, pressure, vibration, shear force, and temperature to the skin of an upper extremity amputee, especially the one who has undergone targeted nerve reinnervation (TR) surgery. In TR patients, sensation from the reinnervated skin is projected to the miss...

Haptic cues may be able to assist an individual who is engaged in a manual control task, freeing visual and auditory attention for other mental tasks. We describe an experiment in which subjects attempted to step at a consistent pace on a stair climber exercise machine which was modified for haptic cuing through the legs. Subjects' visual attention...

Studies have shown locomotor adaptation of the ankle to assistive torques, but the ability of the knee to adapt to assistive forces has not yet been explored. Understanding how humans modulate knee joint kinematics during gait could be valuable for designing assistive devices for stroke patients. In this study we examined how healthy subjects adapt...

In-situ stamping process monitoring plays a critical role in enhancing productivity and ensuring part quality in sheet metal stamping. This paper investigates the realization of two sensing methods to create a tooling-integrated sensing system: mutual inductance-based displacement measurement for sheet draw-in, and distributed contact pressure meas...