This correspondence is a response to Comments on the above article raised by Wen et al. (2023). The authors in Wen et al. (2023) insist that there might be some errors in the Kalman filter derivation procedure, mathematical expression, and computability of high-order error terms in Ko et al. (2022). However, the arguments are not always true. The authors in Wen et al. (2023) misunderstood the derivation of the Kalman filter by the assumption of an unbiased estimator. In addition, they also misunderstood the assumption of noise distribution for the Kalman filter design. In this correspondence, we analyze and refute the comments in a pointby-point fashion.

We present an energy-efficient, scalable neural stim-ulation IC with adaptive dynamic voltage switching, which can be applied to cochlear implant (CI) systems. The stimulation IC generates three different voltage outputs by operating a single-inductor multiple-output (SIMO) boost converter, while an adaptive dynamic voltage switching (ADVS) block selects an appropriate supply voltage for each stimulation channel among those SIMO outputs. The SIMO boost converter is designed to operate over a wide range of its input, which is the rectifier output of the wirelessly powered CI system. The ADVS control as well as the stimulation amplitude control are performed remotely by an external sound processor (SP) of the CI system in real time. For the ADVS operation, the compliance voltage of each stimulation channel is monitored to be used as an input signal for switching to the appropriate supply voltage for the corresponding stimulation channel. The dynamic voltage switching operation is carried out in sub-us, The stimulation IC with ADVS is implemented using a 180-nm BCD process, and its operation and performance are verified through post-layout simulations. When applying a real audio input using decoded data from a prototype SP, the proposed stimulation IC with ADVS demonstrates 36.6% energy saving compared to the conventional stimulation IC.

Positioning is the most basic yet important process in a train control system. In practical train systems, the position of a train is determined with a track circuit, a radio frequency (RF) tag called a “balise”, or a tachometer. A train control center gives each train an automatic train protection (ATP) speed profile computed from the positioning information of both the train and the next train in front it. To successfully operate in a conventional train control system such as ATP/ATO, each train derives its own automatic train operation (ATO) speed profile from the ATP speed profile provided by the control center. However, existing train positioning schemes face many difficulties in terms of installation, maintenance, and repair. To address these difficulties, we consider using 5G NR (New Radio) signals which have a high probability for guaranteeing line-of-sight (LOS) as well as a high sampling rate because they do not require the additional installation of any infrastructure for positioning. In this paper, we propose two positioning schemes for high speed trains (HSTs) based on Kalman filters that make use of 5G NR signals. The first is an HST positioning scheme using a modified Kalman filter and the second is an HST positioning scheme using a deep Kalman filter. Simulation results show that the two proposed schemes achieve better performance in nonlinear non-Gaussian systems as well as in nonlinear Gaussian systems in terms of mean and worst 5% position errors when compared to the existing positioning scheme for HSTs that utilize 5G NR signals.

This paper presents a method of self-intersection detection and resolution for dynamic cylindrical-lattice-based free-form deformation (FFD). The lattice-based approach allows efficient computation of deformation of complex geometries. But excessive deformation can cause visual anomalies such as surface infiltration and distortion. This paper derives a geometrically intuitive sufficient condition to guarantee that the FFD function is a homeomorphism and there is no self-intersection. The FFD function is defined by linear and quadratic B-Spline functions with the control points of the cylindrical lattice cell. The sufficient condition is satisfied if each trilinear function of the nine prism-shaped pentahedrons derived from the cell has a positive Jacobian determinant. The positivity is satisfied if the 12 tetrahedrons derived from the pentahedron have positive volumes. Based on the sufficient condition, the proposed method converts the self-intersection problem into a point-face collision detection and response problem suitable for dynamic simulation. The efficiency and accuracy of the self-intersection detection algorithm is analyzed and compared with a previous method. The results show that the proposed technique allows simulation of excessive deformation of tubular objects in an efficient and realistic manner.

This paper presents an improved haptic interface for the Korea Advanced Institute of Science and Technology Ewha Colonoscopy Simulator II. The haptic interface enables the distal portion of the colonoscope to be freely bent while guaranteeing sufficient workspace and reflective forces for colonoscopy simulation. Its force-torque sensor measures the profiles of the user. Manipulation of the colonoscope tip is monitored by four deflection sensors and triggers computations to render accurate graphic images corresponding to the rotation of the angle knob. Tack sensors are attached to the valve-actuation buttons of the colonoscope to simulate air injection or suction as well as the corresponding deformation of the colon. A survey study for face validation was conducted, and the result shows that the developed haptic interface provides realistic haptic feedback for colonoscopy simulations.

This paper presents a model of frictional contact with soft tissue for the colonoscopy simulator with haptic fidelity. The colonoscopy simulator allows the user to navigate the three dimensional virtual colon constructed from CT (computer tomography) data of patients. The frictional contact model is proposed to integrate the therapeutic procedures such as polyp removal. The proposed model uses the finite element method based on the linear static elasticity to simulate deformation and reflective force including friction effects. The variation of the reflective force is computed according to the contact state, stick or slip state, during sliding contact motions. Simulation results show responses following the Coulomb's friction law.