In this study, we describe the development of a novel calibration robotic system, which is capable of automatically generating various combinations of a six-axis force/torque (F/T) that measures the maximum force information at a point. We proposed a new principle for generating a six-axis F/T by using three vertical forces and three horizontal forces based on a kinematic model. The mechanism of the proposed system was designed and manufactured compactly using a pulley-driven mechanism and a wire-driven mechanism. Consequently, versatile combinations of the F/T were generated by using the force/position control of six motors in the system, and their performance was validated by comparing the data with that of a commercial six-axis F/T sensor. Results showed an error of less than 1.6%. In addition, performance validation was further conducted using artificial intelligence techniques to obtain accurate data with an error below 0.025%.

In this article, we propose an intrinsic contact force sensing method on an arbitrary surface using six-axis force/torque information. An arbitrary surface is defined by a triangle mesh structuring, and the contact sensing solution is achieved by searching the contacted triangle and predicting the actual contact point. The contact sensing algorithm is designed as a three-stage process for swift detection: 1) initial contact triangle selection, 2) solution of the contact point within the triangle plane, and 3) the implementation of a technique for switching the candidate triangle. The performances of the proposed method were evaluated in an experimental setup using a robot manipulator with a commercial force sensor to measure reference data. In addition, to show the usability of the potential robotic applications, the performance verification was performed by measuring the contact force in the complex shape of a commercial collaborative robot.

Shape memory alloy (SMA) has superior actuation capability over the limit of the scale. However, inherently low controllability is a primary issue that hinders practical usage. To address this challenge, this paper presents an SMA-based artificial muscle actuator capable of the displacement sensing through the capacitive sensor. To realize sensing capability, the theoretical model-based design and fabrication process are proposed. Here, we show that the actuator can be controlled at intervals of 100 μm as well as maintaining sensing capability while lifting 90 times heavier than its weight. To exhibit the usefulness of the actuator to an optical device, we integrate the actuator into the mirror tilting device, which has 20 degrees tilting angle. We expect that the proposed actuator can overcome the scale limit of meso-scale devices, which require payload capacity and controllability, simultaneously.

Increasing demand for automation and recent intact trends have accelerated the employment of robots in manufacturing and service areas. Thus, there is a growing demand for easier and safer operation of robots, both by experts and non-professionals. This paper proposes a detachable smart robot teaching device with collision prediction to meet such demands. The proposed device is composed of two modules. One is for easy teaching based on a 6D mouse, and the other is for safe operation by measuring the distance to the surrounding obstacles and predicting the collision situation. The teaching module is used only in a teaching phase and can be separated afterward. A prototype is implemented, and the performance is verified through experiments with a collaborative robot.

Robotic manipulators require contact force sensing capabilities to sense the contact force between the manipulator and an object. Specifically, for humans and robots to coexist in the work environment, the robot must be able to detect an external force applied by a human. This study presents a new intrinsic force sensing method for robot manipulators that can obtain accurate information of the external force applied by a human during human–robot interaction. The method employs a robot cover, which is typically utilized in robot manipulators. Unlike conventional force sensing methods, a six-axis force/torque sensor is placed between the cover and the link of the robot manipulator. As a result, the proposed method provides information of the three-axis contact force applied to the cover surface and its contact location. Therefore, the cover itself becomes a sensorized cover based on the intrinsic force sensing method. To evaluate its sensing performance, the sensorized cover is experimentally validated using reference sensors. Finally, an experiment is performed in which the robot successfully recognizes letters written on the cover, indicating a high level of contact force sensing performance.

Force-sensing system represents one of the vital components of robotic systems for physical interaction performances. This system is facilitated by the force controllable actuators. However, to make a force controllable actuator, it is still a challenging subject for the majority of the robotic system. This paper proposes a novel POWERPACK unit integrated a torque sensor, a harmonic drive and a motor for enabling the force control. The torque sensing element is based on the capacitance sensing to achieve a compact and a simple structure. In this research, reveals the practical details of the POWERPACK and evaluates the performance of the actuator unit.

Various control strategies using trajectory planning, object recognition and learning are researched for avoiding obstacles when legged robot is walking. In this paper, designed trajectory by using Non Uniform Basis Spline (NUBS) curve and control strategy, by using proposed trajectory, to effectively overcome obstacles are presented. The trajectory designed by NUBS curve has several advantages: 1) local modification, 2) tracking velocity control for each domain, and 3) low degree trajectory with a large number of control points. The robot gets remarkable effectiveness when these advantages are used to generate the trajectory for walking and overcoming obstacles. By implementation of the proposed control strategy, quadruped robot can walk over obstacles while keeping its gait, speed and balance without collision although adjusting relatively preferable state which is more suitable position or posture of the walking robot shortly before encountering obstacles is not required. The proposed trajectory and control strategy are discussed, and performance is validated through experimental evaluations.

This paper demonstrates a new haptic display based on soft actuator and soft sensor. The device consists of an array rigid coupling actuator and an array tactile sensor which configured sensor located on the top of actuator. The actuator includes a frame with rigid coupling made by silicone and a dielectric elastomer actuator(DEA). The movement of the DEA is transferred to touch pad via rigid coupling. Thus, it provides a soft, comport touch feeling and eliminates the danger of applying high voltage to the human skin. The actuator can work at a wide range frequency of 0–150 Hz and produce sufficient force of 50 mN over the human hand threshold. The tactile sensor can measure the pressure, locate the objects and send the feedback signals to control the actuator. In this work, a 8×12 haptic tactile display is made with high resolution. In addition, the high voltage signal processing also developed to generate variable 0–3.5 kV, and can control individual cell by using the dynamic scanning actuation algorithm. Then, it can display any shape such as a circle, a smile/sad face, a star, etc. In the future, we will build the “emotion touch pad” system which can transfer a person's emotion to another one via internet.

This paper presents a highly sensitive dual mode tactile and proximity sensor for robotic applications that uses Carbon Microcoils (CMCs). The sensor consists of multiple electrode layers printed on a Flexible Printed Circuit Board (FPCB) and a dielectric substrate into which the CMCs are dispersed. The dielectric layer is simply put on the top of the FPCB. Thus, the sensor provides ease of fabrication and robustness against repetitive external contacts because the dielectric layer protects the electrodes. The electrical properties of the sensor are changed when an object approaches or touches the sensor. The sensor uses a capacitive sensing mode for tactile sensing and an inductive sensing mode for proximity sensing. CMCs amplify the change of the sensor signal because of electrical impedance formed by the CMCs, and thus, the sensitivity of the sensor increases. We fabricate the prptotype sensor with the dimensions of 30 × 30 × 0.6 mm3, and with 3 mm spatial-resolution. The sensor detects the applied pressure up to 330 kPa and the distance of an object as much as 150 mm away.

This paper aims to develop novel surgical forceps integrated with a three-axis force sensor for robot-assisted minimally invasive surgery (RMIS). To detect accurate force sensing, a force sensing system is integrated to a gripper of a surgical instrument. At the gripper side, two possible locations are considered, and the sensing system is installed to the distal region of the gripper, which gives major advantages such as the gripper's minimization, palpation function, and multi-axis force sensing. Based on the capacitive-type sensing method, the sensor enables the direct measurement of the three-axis force applied to surgical gripper tip. The sensorized gripper is simply designed at a low cost, composed of only four mechanical parts, and, the forceps including two grippers are installed to an instrument that is able to conduct a grasping motion. Therefore, it is used to evaluate the performance of the force sensing system. The sensorized forceps are experimentally validated by using a commercial sensor in an experimental set-up.

This paper presents a grasping force-feedback user interface (GFUI) which transfers the accurate kinesthetic force detected during robot-assisted minimally invasive surgery (RMIS) to a user, and allows the users to perform grasping motions with articulation and intuition. Using the GFUI, a developed robot hardware (S-surge) is controlled, and the force data measured from the robot are reflected to the GFUI. To evaluate the effect of grasping force-feedback control using the GFUI, a group of subjects (n=10) participated in a standard peg transfer tasks with and without the feedback control. To conduct the tasks, a developed robot hardware and a commercial haptic device were used which make the entire surgical environment including the GFUI as a master-slave controlled system. As a result, the performance of the GFUI was verified through the conducted tasks using the entire surgical system.

Aiming to apply soft actuators in driving a walking robot, the design, fabrication and locomotion of a bio-inspired printable hexapod robot are studied. The robot mimics the insect's design and walking posture by driving six legs with alternating tripod gait which provides its locomotive adaptability on flat terrains. The versatile movements of the robot's leg are achieved by using soft and multiple degree-of-freedom actuators. The actuators are made by dielectric elastomers with a simple mechanism based on antagonistic configuration. By using 3D printing method, the actuator can be embedded into the frame of the robot and a control system is developed. Finally, the robot's locomotion is successfully demonstrated with variable speeds and stride lengths.

This paper presents a novel surgical instrument integrated with a four-degree-of-freedom (DOF) force sensor. By adopting the capacitive transduction principle, the sensor enables the direct sensing of normal and shear forces at surgical instrument tips. Thus, three-DOF pulling forces and a single-DOF grasping force can be measured for haptic feedback control of robotic minimally invasive surgery systems. The sensor consists of four capacitive transducers, and all the transducers including analog signal processing units are embedded in small surgical instrument tips. The four-DOF force sensing is enabled thanks to the four capacitive transducers by using the force transformation method. In this study, the instrument is designed and manufactured to be adaptable to the open-source surgical robot platform, called Raven-II. In addition, the sensing system is experimentally validated through its application to the Raven-II by using a reference force sensor.

This paper presents a grasper-integrated force sensor that provides the capability of measuring dual axial forces at the tip of surgical robot for minimally invasive surgery (MIS). On the sensorized forceps, the combination of dual axial forces measured at each side of grasper presents three axial pulling and single axial grasping force sensing, which provide force feedback control using haptic device. It consists of simple structure of triangular prism shape and two capacitive-type pressure sensor cells based on elastomeric polymer which provides the information on normal and shear forces. The sensing principle is to compare the difference between responses of two pressure sensors when the surface of the sensor contacts to the tissue. A sensorized forceps is fabricated by employing the molding method and electronics for signal processing is embedded. Finally, experimental evaluations are performed and its feasibility is validated.

This paper presents a multi-axial force sensing system for haptic feedback of minimally invasive robotic surgery. The system consists of a 3-axial force sensor located on the wrist of surgical grasper and a torque sensor which plays a role of pulley for driving tendons. The 3-axial force sensor measures magnitude and direction of manipulation forces when the grasper grasps and pulls the tissue, while the torque sensor measures grasping force transferred through the driving tendons. The sensors and a grasper mechanism are designed and manufactured. For the calibration and verification of the prototype sensors, a testbed which simulates tissue manipulation is built and experiments are performed to evaluate the sensing system.

This paper presents a preliminary design and experimental results of a multi-axial contact force sensor for robotic surgery graspers. The sensor is a thin-film type capacitive one with a multiple cell structure capable of measuring normal and shear forces at contacts simultaneously. The structure of the sensor is determined via numerical optimization for maximizing sensitivity and based on the results, a prototype is fabricated by employing the silk-screening method. The characteristics of the sensor are evaluated with a multi-axial sensor calibration set-up and the sensitivities for two directional shear forces and a normal forces are measured to be 10.1, 10.3 and 6.1%, respectively. In this study, the feasibility of the sensor is confirmed as the proof-of-concept. In our future studies, a miniaturized pair of the proposed sensor will be embedded to a surgery grasper for in vitro validation.

Recently, Dielectric Elastomer Actuator(DEA) comes to the market successfully by introducing commercial products such as tactile interfaces for mobile applications. As an advanced application, we present a tactile display device actuated with dielectric elastomer actuator(DEA) in this paper. By employing fluid coupling between the touch spot and the actuator, the device ensures the comfort of touch and the safety of operation from the high driving voltage while contacting with the human skin. In addition, it is compatible with SMT(Surface Mount Technology), which can be easily plugged into PCB(Printed Circuit Board)s like semiconductor chips and extend to the arrayed tactile display, easily. In this paper, its working principle is overviewed and the actual design with fabrication procedures are described in details. Finally, a prototype is made and its performance is evaluated experimentally.