The instantaneous center of rotation (ICOR) is essential engineering information, providing wheel slip data for fully autonomous skid-steering mobile robots driven by deep learning-based dead-reckoning algorithms. Conventionally, cost-effective and compact inertial measurement unit (IMU) sensors based on microelectromechanical systems (MEMSs) have been employed for ICOR measurement. However, these sensors inherently rely on the differential value of gyroscope data, leading to significant estimation errors due to the amplified noise at low sampling rates. To address this challenge, we developed an acceleration sensor array based on a fiber Bragg grating, inspired by existing MEMS acceleration sensor arrays, which allows ICOR estimation solely from the acceleration data provided by two sensors at the beginning of rotation. The estimation accuracies in the clockwise and counter-clockwise directions were measured to be 3.1 ± 5.1 mm and 3.7 ± 9.9 mm, respectively. Furthermore, a peak detection algorithm was proposed for extracting the peak acceleration under different ICOR conditions using the variance and Bollinger bands. The precision level was comparable to those of optical cameras and MEMS IMU sensors that use computationally intensive algorithms, such as Kalman filters, even without differentiation. This breakthrough in measurement capability opens up the possibility for real-time ICOR estimation, allowing the complete automation of skid-steering-based robots and benefiting fields constrained by the structural limitations of conventional MEMS IMU sensors.

Motion capture systems are gaining much attention in various fields, including entertainment, medical and sports fields. Although many types of motion capture sensor have been emerging, they have limitations and disadvantages such as occlusion, drift and interference by electromagnetic fields. Here, we introduce the novel wearable motion capture system using fiber Bragg gratings (FBGs) sensors. Since the human joints have different degrees of freedom (DOF), we developed three types of sensors to reconstruct the human body motion from the strains induced on the FBGs. First, a shape sensor using three fibers provides the position and orientation of joints in three dimensional space. Second, we introduce the angle sensor which is capable of measuring bending angle with high curvature using single fiber. Lastly, to detect the twisting of joints, a sensor with fiber attached on a soft material spirally is used. With the optical fiber based motion capture sensors, we reconstruct the motion of arm in realtime. In detail, the joints of the arm include the sternoclavicular, acromioclavicular, shoulder and elbow. By arranging the three types of sensors on the joints in accordance with the DOF, the accuracy of the reconstructed motion is evaluated, resulting in an average error below 2.42°. Finally, to prove the feasibility of applying in virtual reality, we successfully manipulate the virtual avatar in real-time.

Shape tracking using a fiber Bragg grating sensor is a promising tool due to its thin, flexible, and weightless nature. Conventional investigations attached optical fibers with a metal rod which limited the curvature due to its stiffness and increased distance between the center of the fiber and that of the sensor. We fabricated ultrathin flexible shape sensor with 110 mm length and 560 μm diameter. Its low Young's modulus and small diameter makes it suitable for application in minimally invasive surgical robot such as active cannula. The sensor causes only miniscule resistance when the cannula rotates or moves, and allows extra spaces for other surgical tools thanks to its small diameter. After the calibration, the sensor was integrated to the active cannula and overall position of the sensor was tracked. It showed an average error of 3.17 ± 1.21 % of the lengths of the measured nodes from the fixed starting point. The error was comparable to the outer diameter of the cannula, 2.8mm.

A precise and implantable micromanipulator is presented for automatically advancing electrodes during single unit recordings in freely-behaving animals. The modular design and enhanced clamping mechanism with simple mechanical components are designed to provide reliable linear motion using a piezo motor with a stroke of 3 mm. To be specific, a closed loop control system, based on the position feedback from a magnetoresistive (MR) sensor, was implemented to overcome the non-linear characteristics of the piezo motor and to locate electrodes precisely at the targeted position with the accuracy of 1 μm, even under load. The weight of the micromanipulator is only 0.84 g when it is fully assembled with the MR sensor, PCBs, and connectors. In addition, a protective cover is employed to prevent breakage during semi-chronic recording. The positioning performance of the micromanipulator was tested at various loading conditions using various control methods. Finally, the activities of a single unit were isolated successfully using small step adjustments, such as 1 to 5 μm, in freely-moving mice.

This paper introduces biohybrid microsystems actuated by cardiomyocytes, such as microcantilever, microrobot, and micropump. The microfabicated biohybrid microcantilever can measure the contractile force of self-organized cardiomyocytes. The microcantilever is made of a biocompatible PDMS substrate, using a simple microfabrication technique and a specially designed 3D micromolding aligner. The contractile force of the cardiomyocytes makes a bending displacement of the microcantilever. Conversely, from the displacement, we can estimate the contractile of the cardiomyocytes on the microcantilever. The bending motion of the microcantilever can be applied as a biohybrid actuator of microrobot. We have developed a novel method to fabricate a crab-like microrobot that can actuate for a long period under a physiological condition. The microrobot consists of three separate front and rear legs which have a shape of the microcantilever. The performance of our crab-like microrobot was measured at an average velocity of 100 mum/s, and the estimated total distance it traveled was 50 m for a one-week period. Finally, a micropump actuated by the self-beating cardiomyocytes is fabricated and the pumping performance is demonstrated.