Miniaturization of robotic grippers enables precise manipulation of small-size objects. However, most microgrippers are actuated by rigid actuators, and thus retain challenges such as micro-fabrication, complex structure, and lack of compliance. Here, we present a compliant microgripper driven by a soft polymer actuator. The proposed millimeter-scale soft polymer actuator can produce a linear displacement and output force with a fast operation. Then, we designed the gripper linkage to convert the linear displacement of the actuator into a gripping motion. Fabricated compliant microgripper has a size of$\boldsymbol{10\times 10\times 10}\ \mathbf{mm}^{3}$and a weight of 0.36 g, with a maximum gripping width of 8 mm. Demonstration of the gripper shows the feasibility of gripping various sub-millimeter scale objects regardless of their shape owing to its compliance.

Tendon-driven flexible endoscopic surgical robots have been developed to access narrow curved paths without incision. Robot shape information is essential for precise control and to prevent unwanted tissue damage. In this paper, we propose a joint angle sensing method using coiled soft sensors to estimate the shape of the hyperredundant manipulator, which is commonly used in flexible endoscopic surgical robots. The soft sensors can be fabricated with small size and are highly stretchable, such that by being pre-stretched, they can be integrated between individual joints, maintain a center hollow, and sense both compression and extension. The pre-stretch length is experimentally selected by using the sensor linearity to maximize the potential sensitivity. We validated the proposed design using a two-degree of freedom (DOF) single joint manipulator by implementing two sensors; sensors at all joints could sense joint angle independently and simultaneously with a root-mean-square error (RMSE) less than 2.53°. Based on the proposed method, a two-DOF configuration of the hyperredundant manipulator that can be used in real applications was achieved, following a constant curvature model in real time with values RMSE of 2.30° and 2.63°, for pitch and yaw joint angle respectively.

Dielectric elastomers are electro-mechanically coupled transducers that display a nonlinear viscoelastic stress-strain relationship. Modeling and controlling such nonlinear materials and actuators are of great challenge. A spring roll dielectric elastomer actuator is a linear actuator composed of a spring and sheets of wrapped dielectric elastomers. Since its shape and actuation performance resemble a human muscle, its application as an artificial muscle is investigated. To verify its applicability, the actuator’s controllability and time-dependent actuation behavior are examined. In this paper, we derive a multiple time-constant model specifying the response of a long-term dynamic loading of the spring roll dielectric elastomer actuator. Our modeling approach is based on multiple viscoelastic elements, having different time responses, superposed into one rheological model. In addition to viscoelasticity, the model includes the effects of the spring core, external mechanical load, the internal stress of the elastomer, and the applied dynamic voltage signal, so that it can be applied in various working conditions. Experiments and simulations are conducted to confirm the applicability and accuracy of the proposed long-term multiple time-constant model.

This paper proposes a muscle-like SMA (Shape Memory Alloy) actuator with an active cooling system for efficient response. An SMA coil spring is embedded into a stretchable coolant vascular for soften structure of robots. In order to design a flexible, lightweight, and fast-response soft actuator with the SMA coil spring and coolant circulation system, a modeling based approach has been conducted. Analysis of coolant effects has been conducted in aspects of heating speed, cooling speed, and energy consumption based on both theoretical and empirical studies. From thermomechanical and heat transfer model between SMA and coolant, the actuation times in the case of heating and cooling phase have been estimated. From experimental results, Mineral oil is selected as the optimal coolant, and the maximum actuation frequency was measured as 0.5Hz for 40% contraction lifting 1kg.

In this paper, we report a self-sensing soft tactile actuator based on Dielectric elastomer actuator (DEA) for wearable haptic interface. DEAs are one of electroactive polymer actuators, which are reported to have large area strain and fast response speed. A soft tactile actuator is constructed of a multi-layered DEA membrane layer, a passive membrane layer, and an inner circular pillar. The soft actuator was optimized by varying the geometry, and the force and displacement tests were conducted under a frequency range of 0 to 30 Hz. The selected actuator produces an output force up to 0.9 N, with a displacement of 1.43 mm. To provide accurate physical force feedback to the user, the actuator is integrated with a 1.1 mm thick film-type soft force sensor that enables feedback control. Under the pressure, touch layer contacts with the core, and the light inside the core scatters to the touch layer. A fabricated soft force sensor can measure the force in a range of 0 to 1.25 N under various frequency ranges. Our wearable prototype exhibits high output force of 0.9 N, as well as flexibility, conformity, and light-weight structure (3.2 g).

With recent strong interests in flexible displays and wearable devices allowing them to be mechanically robust against deformation, sensors and actuators for human-machine interfaces are required to be soft to be embedded into flexible mechanisms. We introduce recent approaches in soft and flexible sensors and actuators, and discuss current issues to be solved in the topics. An open discussion will take place on the future of these types of sensors and actuators for human-robot interaction systems.

Summary form only given. This talk introduces a historical change of haptics research based on personal experience. For a long time, researchers had proposed various force or tactile display devices which need be placed on a table. The devices were mainly composed of very stiff supporting structure and rigid actuating/ sensing components such as electric motors, piezoelectric actuators, force/torque sensors and etc. With recent development of visual display devices, haptic interfaces have been investigated for interacting with portable touchscreen devices. For installation of haptic interface into touchscreen devices, the haptic components need to be miniaturized and sometimes they have to be transparent. Now, we have more challenging issues since flexible electronic devices and wearable devices are rapidly arousing people's interest in the market as well as a field of research. In order to apply haptics technology to future flexible interfaces, we need to consider new appearance of actuators and sensors. This talk starts from brief description of compact tactile displays and haptic interfaces for touchscreens, and mainly introduces current research activities for flexible and transparent haptic interface.

We have developed an flexible electro-active polymer (EAP) actuator and a thin flexible visual display with 3×3 array configuration via polymer technology. The flexible actuator consists of nine EAP cells vertically moving in response to change in their thickness. The flexible display uses polymer based optical waveguide allowing light to scatter only at specific area. A pressure sensor is installed under the integrated module. The performance of the actuator is proved to be sufficient for satisfying perceivable range of human touch sense.

In this paper, we present a haptic touchscreen interface for mobile devices. A surface actuator composed of two parallel plates is mounted between a touch panel and a display module. It generates haptic feedback when a user input on a touch screen. The electrostatic force is generated when two parallel plates are charged and this phenomenon causes haptic feedback. When an input is detected on the touch screen, multimodal feedback that includes not only basic visual and auditory feedback but also haptic feedback occurs appropriately. Then, a user feels realistic physical feeling in the fingertips and it provides the feeing such as pressing a real keyboard. We have designed and implemented an actuator, thin and transparent, to provide haptic feedback and an interactive architecture to perform multimodal output.

This paper deals with a motion-based remote control system to improve the menu control of IPTV. A 6-DOF motion sensor and hybrid vibrators are embedded into the device. With wrist motion, a user controls the position of the pointer on the screen intuitively. Haptic feedback is provided in response to the manipulation of a GUI element. From the usability test, we observed that the motion sensing and haptic feedback improve the speed of the menu control and decrease the manipulation load. Particularly, a remote controller adopting a combination of gyroscope-based motion sensing and impact feedback showed the best performance.

This paper proposes a new interactive interface TAXEL, which aims at developing a reconfigurable self-morphing visio-haptic interface. We first present the overall architecture and concept of a self-morphing visuo-haptic interface. Key hardware components are developed and tested, including three tactile actuators using a piezoelectric active linear actuator, a passive MR fluid actuator, and a thin film-type actuator, respectively, and a flexible visual display based on the light-waveguide technology. Using the developed components, a tactile platform that includes a 8×16 array of the linear actuators is implemented for a proof of concept. A rendering engine is also designed for the tactile platform with emphasis on the use of haptic feedback together with GUI. We also carried out a user study with virtual button simulation as a benchmark to evaluate the performance of the TAXEL tactile platform. Lastly, an integrated system with a visual display is demonstrated along with several application examples.

The objective of this research is to propose and design a compact tactile display module and verify its performance in a pen-like haptic interface, particularly on the touch screen. A small, safe, silent and light tactile display module with low power dissipation has been built. Based on this module, we present the Ubi-Pen, a pen-like haptic interface providing texture and vibration stimuli. Preliminary evaluations indicate it can satisfactorily represent tactile patterns. We also evaluate its capacity to support GUI operations by producing a simple click-like feedback when buttons are pressed. In addition, it provides texture sensation when a user rubs an image displayed on a touch screen.

This paper proposes a tactile display device providing pin-array type tactile feedback and thermal feedback. The pin-array type tactile display is composed of a 6times5 pin-array that is actuated by 30 piezoelectric bimorphs. Micro shape and vibrotactile feedback can be generated by the device, and various planar distributed patterns can be displayed as can braille cell patterns. The thermal feedback device is composed of a thin film resistance temperature detector (RTD), a Peltier thermoelectric heat pump and a water cooling jacket. Users can discriminate among different materials by considering the temperature variation that can be sensed as they touch an object's surface. This paper also includes an experimental evaluation of the device to prove effectiveness of displaying textures. Material property discriminating evaluation was conducted using thermal feedback device that displays simulated temperature profile. To determine the relation between stimulated area and thermal perception sensitivity, a thermal perception experimental setup is developed and the experimental method is described

This paper describes an experiment on the evaluation of human sensibility by monitoring responses to changes in the frequency and amplitude of a tactile display system. Preliminary tasks were performed to obtain adequate adjectives concerning texture presentation. And, in the main experiment, 7 selected sandpaper types and 15 selected combinations of frequencies and amplitudes of a tactile display were utilized to quantitatively evaluate the ten adjectives determined during preliminary tasks. The data show that a relationship exists between the independent variables (frequency, amplitude, and grit size) and the dependent variable (perceived texture). We then considered the perceived tactile perception in relation to viscoelastic properties of the human fingerpad. We obtained remarkable psychophysical results and also identified the relation between tactile sensation and the mechanical stimuli from a biomechanical viewpoint

This paper presents a novel haptic mouse KAT (KAIST artificial touch) that can be used as a human-computer interface and offers the capability of displaying properties such as patterns, gratings and roughness. A small planar-distributed pin array is developed. The array can represent micro-scale shapes with various surfaces, such as gratings, grooves, patterns, shapes of icons, and Braille, and provides the user with cutaneous stimuli. Since the tactile display unit is small enough to be embedded into a computer mouse, we developed a new texture display mouse. The performance of its texture display capability was verified. In addition, two psychophysical experiments have been conducted in order to ascertain the influence of vibrotactile stimuli. The first experiment showed that vibrational stimuli could be effective in the perception of patterns while from the second experiment, the functional relation between perceived roughness and components of vibrotactile stimuli was obtained. The experimental results have been applied to the development of a test-bed program

The sense of touch provides humans with the ability to determine the shape and surface properties of objects. Although touch is an important part of daily life for object manipulation and exploration tasks, users are, unfortunately, rarely provided with the opportunity to use their sense of touch while interacting with computers. To rectify this, this article presents a novel haptic mouse system that can be used as a human-computer interface with the capability for holistic haptic feedback, including contact force, surface properties, and thermal feedback. The system is composed of 3 main parts. First, the 5-bar mechanism, which comprises the lowermost part of the mouse's body, has been adapted to realize 2-DOF translational force feedback. This mechanism helps the user to feel the contact force, stiffness, and size of a virtual object while exploring a graphical environment. Second, a small tactile display was developed. It has a planar-distributed pin array, and it can represent microscale shapes with various surfaces, such as gratings, grooves, patterns, shapes of icons, and Braille, thereby providing the user with cutaneous stimuli. Third, because the ability to sense temperature is an important factor in the discrimination of the surface property of an object, thermal feedback is provided to the user. The performance of each part and their combinations has been evaluated, and the system shows a remarkable ability to provide users with tactual information while they simply use the mouse without any additional interfaces.

In this paper, we suggest a mouse-type integrated tactile display system that provides kinesthetic force, distributed pressure, vibration and skin stretch. The system consists of two parts: a 2-DOF force feedback mechanism for kinesthetic force display and a tactile display part for providing normal stimulation to the skin and the lateral skin stretch. A tactile display device, using eight piezoelectric bimorphs and a linear actuator, is fabricated and attached to a 2-DOF translational force feedback device to simultaneously simulate the texture and stiffness of the object. The developed system was adopted as a test bed to study the factors affecting perception of surface properties. We investigate three things: effective stimulating methods, limitation of surface discrimination based on kinesthetic force and the effectiveness of combining kinesthetic force feedback with tactile feedback. Seven kinds of stimulating methods are investigated to study effective methods in simulating texture. In addition, in order to find out the role of skin stretch during perceiving texture, the discernment abilities of active touch (rubbing), laterally-active-display and moving-wave-form have been compared.

This paper describes a novel haptic mouse system which conveys kinesthetic and tactile information simultaneously in virtual environments. The haptic mouse system can provide 2-DOF translational force feedback, vibration, normal pressure, skin stretch and thermal feedback, all of which are important physical quantities of sensing object's shape, stiffness and surface properties. The system can simulate small scale shapes and roughness of surface textures using cutaneous cues generated by individual drives of a 6/spl times/8 pin array. Since thermal differences among surfaces of virtual objects is one of dominant factors in perceiving texture, a thermal feedback unit composed of a heat conduction plate and a temperature sensor is also embedded into the tactile display system. The developed system can be used as a testbed in psychophysical study on tactile perception. We have investigated the influence of the frequency variation on perceived roughness using the haptic mouse system since vibrotaction has been considered as a key factor affecting perception of fine textures by physiology researchers. In order to find out the relation of roughness and vibration, two psychophysical experiments have been performed. The correlation between the vibration frequency and the texture shows that there are certain transitions of perceived roughness. The experimental results yield that the vibrating stimulus is more effective for displaying a fine surface than static displacement display, and it shows a possibility to display finer texture, exceeding the physical limitation of the device.

Tactile sensation is essential for many exploration and manipulation tasks not only in a real environment but also in a virtual environment. We suggest the design of an integrated tactile display system that provides kinesthetic force, pressure distribution, vibration and slip/stretch. The system consists of two parts: a 2 DOF force feedback device for kinesthetic display and a tactile feedback device for displaying the normal stimulation to the skin and the skin slip/stretch. Psychophysical experiments measure the effects of fingerpad selection, the direction of finger movements and the texture width on tactile sensitivity. We also investigate the characteristics of lateral finger movement while subjects perceive different textures. From the experimental results, the principal parameters for designing a tactile display are suggested. A tactile display device, using eight piezoelectric bimorphs and a linear actuator, is implemented and attached to a 2 DOF translational force feedback device to simultaneously simulate the texture and stiffness of the object. As a result, we find out that the capability of the suggested device is sufficient to display physical quantities for tactile sensing.

This paper proposes a scheme to produce realistic force reflection in a needle insertion problem. The target system is a spine needle biopsy simulator for tumor inspection by needle insertion. Simulated force is calculated using a 3D human tissue model and the orientation and position of the needle, and is produced through the PHANToM/sup TM/ device. To generate realistic force reflection, the directional force of the needle has been generated by a related tissue model, and the rotational force is generated using a pivot to keep the needle in the initial inserted direction after puncturing the skin. Since the haptic device has limitations in generating high stiffness and large damping, a scale-down model and digital filter are used to stabilize the system.

Shows how to implement haptic rendering for a needle insertion problem with a volume graphic model. The target is a spine biopsy simulator for tumor inspection by needle insertion. Simulated force is calculated from the relationship between voxel data and the orientation and position of the needle. At first, it is generated using PHANToM/sup TM./ The needle puncturing resistive force is calculated from a stiffness model and the correction force to give physical constraint to the needle is derived using a pivot. For more realistic force feedback voxel based modeling is considered. MRI T1 value and CT density can be used to give physical properties to voxel. Soft tissue can be modeled as a damper using MRI value in the needle insertion problem, and the stiffness of hard tissue is derived from CT density. Skin deformation is modeled with Kelvin's viscoelastic model. Since the high stiffness and large damping need to be simulated, it is attempted to generate force using active actuators and passive devices together.