arXiv subjects

Tsu-Chin Tsao

Publications and source records attributed to Tsu-Chin Tsao.

9 recordsLinked to original sources

arXiv2026

A Master-Slave Robot Manipulator for Needle-Based Teleoperation in MRI Chamber

We present a MR safe, master-slave robot manipulator for abdominal interventions in the MRI chamber. A human operated 2+1-DoF master controller manipulator transmits motion and force to a 2+1-DoF slave manipulator via fluid transmission. Jointly, a digital master controller provides multimodal control capability beyond common split axis or mode switchable hybrid human-digital controller configurations found in previous studies. High input impedance, low-leakage, elastomeric fluid actuators are delegated to remote angulation control. Low-friction graphite piston cylinders are delegated to needle insertion axis remote actuation given the sub-newton force transparency and sub-millimeter motion transmission over bedside fluid piping lengths. The device enables real-time MRI guided interventions allowing manual, digital, hybrid, and collaborative control modes. Collaborative tasks such as assisted tissue penetration, fault-driven virtual fixture, and motion compensation through feedback control are presented in this paper. Preliminary MR scanner results demonstrate manipulator functional viability for an in-vivo pig experiment in bedside, manual control mode configuration.

cs.RO↗

arXiv2026

Unified and Efficient Analysis of Machining Chatter and Surface Location Error

Although machining chatter can be suppressed by the choice of stable cutting parameters through means of stability lobe diagram (SLD), surface roughness still remains due to the forced vibration, which limits surface quality, especially in the surface finish. Better cutting parameters can be achieved considering surface location error (SLE) together with SLD. This paper proposes an innovative modeling framework of the machining dynamic system that enables efficient computation of the chatter stability and SLE. The framework mainly embodies two techniques, namely semi-discretization method (SDM) and lifting method. The machining dynamics system is mathematically expressed as an angle-varying delay differential equation (DDE). The SDM approximates the angle-varying and delayed terms to ordinary terms using zero-phase interpolations and governs the discrete angle-varying dynamics system. Then, the system is merged over the tooth passing angle using the lifted approach to establish an explicit dynamic system in the compact state-space form. Based on the compact state-space model, the chatter stability and SLE prediction are easily and efficiently conducted. Simulation results show the improved efficiency of the proposed method over other well-known methods.

eess.SY↗

arXiv2025

High-Precision Surgical Robotic System for Intraocular Procedures

Despite the extensive demonstration of robotic systems for both cataract and vitreoretinal procedures, existing technologies or mechanisms still possess insufficient accuracy, precision, and degrees of freedom for instrument manipulation or potentially automated tool exchange during surgical procedures. A new robotic system that focuses on improving tooltip accuracy, tracking performance, and smooth instrument exchange mechanism is therefore designed and manufactured. Its tooltip accuracy, precision, and mechanical capability of maintaining small incision through remote center of motion were externally evaluated using an optical coherence tomography (OCT) system. Through robot calibration and precise coordinate registration, the accuracy of tooltip positioning was measured to be 0.053$\pm$0.031 mm, and the overall performance was demonstrated on an OCT-guided automated cataract lens extraction procedure with deep learning-based pre-operative anatomical modeling and real-time supervision.

cs.RO↗

arXiv2025

Improving Needle Penetration via Precise Rotational Insertion Using Iterative Learning Control

Achieving precise control of robotic tool paths is often challenged by inherent system misalignments, unmodeled dynamics, and actuation inaccuracies. This work introduces an Iterative Learning Control (ILC) strategy to enable precise rotational insertion of a tool during robotic surgery, improving penetration efficacy and safety compared to straight insertion tested in subretinal injection. A 4 degree of freedom (DOF) robot manipulator is used, where misalignment of the fourth joint complicates the simple application of needle rotation, motivating an ILC approach that iteratively adjusts joint commands based on positional feedback. The process begins with calibrating the forward kinematics for the chosen surgical tool to achieve higher accuracy, followed by successive ILC iterations guided by Optical Coherence Tomography (OCT) volume scans to measure the error and refine control inputs. Experimental results, tested on subretinal injection tasks on ex vivo pig eyes, show that the optimized trajectory resulted in higher success rates in tissue penetration and subretinal injection compared to straight insertion, demonstrating the effectiveness of ILC in overcoming misalignment challenges. This approach offers potential applications for other high precision robot tasks requiring controlled insertions as well.

cs.RO↗

arXiv2025

Control Modes of Teleoperated Surgical Robotic System's Tools in Ophthalmic Surgery

The introduction of a teleoperated surgical robotic system designed for minimally invasive procedures enables the emulation of two distinct control modes through a dedicated input device of the surgical console: (1) Inside Control Mode, which emulates tool manipulation near the distal end as if the surgeon was holding the tip of the instrument inside the patient's body; (2) Outside Control Mode, which emulates manipulation near the proximal end as if the surgeon was holding the tool externally. The aim of this research is to compare the surgeon's performance on these two modes of operation along with various scaling factors in a simulated vitreoretinal surgical setting. The console of Intraocular Robotic Interventional Surgical System (IRISS) was utilized but the surgical robot itself and the human eye anatomy was simulated by a virtual environment projected microscope view of an intraocular setup to a VR headset. Five experienced vitreoretinal surgeons and five subjects with no surgical experience used the system to perform four fundamental tool/tissue tasks common to vitreoretinal surgery: touch and reset; grasp and drop; inject; circular tracking. Results indicate that Inside Control outperforms Outside Control across multiple tasks and metrics. Higher scaling factors generally performed better, particularly for reducing trajectory errors and tissue damage. This improvement suggests that larger scaling factors enable more precise control, making them the preferred option for fine manipulation. However, completion time was not consistently reduced across all conditions, indicating that surgeons need to balance speed and accuracy based on surgical requirements. By optimizing control dynamics and user interface, robotic teleoperation has the potential to reduce complications, enhance dexterity, and expand the accessibility of high precision procedures to a broader range of practitioners.

cs.RO↗

arXiv2025

Safe Robotic Capsule Cleaning with Integrated Transpupillary and Intraocular Optical Coherence Tomography

Secondary cataract is one of the most common complications of vision loss due to the proliferation of residual lens materials that naturally grow on the lens capsule after cataract surgery. A potential treatment is capsule cleaning, a surgical procedure that requires enhanced visualization of the entire capsule and tool manipulation on the thin membrane. This article presents a robotic system capable of performing the capsule cleaning procedure by integrating a standard transpupillary and an intraocular optical coherence tomography probe on a surgical instrument for equatorial capsule visualization and real-time tool-to-tissue distance feedback. Using robot precision, the developed system enables complete capsule mapping in the pupillary and equatorial regions with in-situ calibration of refractive index and fiber offset, which are still current challenges in obtaining an accurate capsule model. To demonstrate effectiveness, the capsule mapping strategy was validated through five experimental trials on an eye phantom that showed reduced root-mean-square errors in the constructed capsule model, while the cleaning strategy was performed in three ex-vivo pig eyes without tissue damage.

cs.RO↗

arXiv2025

Spherical Pendulum with Quad-Rotor Thrust Vectoring Actuation -- A Novel Mechatronics and Control Benchmark Platform

Motor-actuated pendulums have been established as arguably the most common laboratory prototypes used in control system education because of the relevance to robot manipulator control in industry. Meanwhile, multi-rotor drones like quadcopters have become popular in industrial applications but have not been broadly employed in control education laboratory. Platforms with pendulums and multi-rotor copters present classical yet intriguing multi-degree of freedom (DoF) dynamics and coordinate systems for the control system investigation. In this paper, we introduce a novel control platform in which a 2-DoF pendulum capable of azimuth and elevation rotation is actuated through vectored thrust generated by a quadcopter. Designed as a benchmark for mechatronics and nonlinear control education and research, the system integrates detailed mechatronic implementation with different control strategies. Specifically, we apply and compare small perturbation linearization (SPL), state feedback linearization (SFL), and partial feedback linearization (PFL) to the nonlinear system dynamics. The performances are evaluated by time specifications of step response and Root-Mean-Square (RMS) error of trajectory tracking. The robustness of the closed-loop system is validated under external disturbances, and both simulation and experimental results are presented to highlight the strengths and limitations of the nonlinear model-based control approaches.

eess.SY↗

arXiv2023

Fault-tolerant Control of an Over-actuated UAV Platform Built on Quadcopters and Passive Hinges

Propeller failure is a major cause of multirotor Unmanned Aerial Vehicles (UAVs) crashes. While conventional multirotor systems struggle to address this issue due to underactuation, over-actuated platforms can continue flying with appropriate fault-tolerant control (FTC). This paper presents a robust FTC controller for an over-actuated UAV platform composed of quadcopters mounted on passive joints, offering input redundancy at both the high-level vehicle control and the low-level quadcopter control of vectored thrusts. To maximize the benefits of input redundancy during propeller failure, the proposed FTC controller features a hierarchical control architecture with three key components: (i) a low-level adjustment strategy to prevent propeller-level thrust saturation; (ii) a compensation loop for mitigating introduced disturbances; (iii) a nullspace-based control allocation framework to avoid quadcopter-level thrust saturation. Through reallocating actuator inputs in both the low-level and high-level control loops, the low-level quadcopter control can be maintained with up to two failed propellers, ensuring that the whole platform remains stable and avoids crashing. The proposed controller's superior performance is thoroughly examined through simulations and real-world experiments.

cs.RO↗

arXiv2014

Design and Implementation of Repetitive Control based Noncausal Zero-Phase Iterative Learning Control

Discrete-time domain Iterative Learning Control (ILC) schemes inspired by Repetitive control algorithms are proposed and analyzed. The well known relation between a discrete-time plant (filter) and its Markov Toeplitz matrix representation has been exploited in previous ILC literature. However, this connection breaks down when the filters have noncausal components. In this paper we provide a formal representation and analysis that recover the connections between noncausal filters and Toeplitz matrices. This tool is then applied to translate the anti-causal zero-phase-error prototype repetitive control scheme to the design of a stable and fast converging ILC algorithm. The learning gain matrices are chosen such that the resulting state transition matrix has a \textit{Symmetric Banded Toeplitz} (SBT) structure. It is shown that the well known sufficient condition for repetitive control closed loop stability based on a filter's frequency domain $H_\infty$ norm is also sufficient for ILC convergence and that the condition becomes necessary as the data length approaches infinity. Thus the ILC learning matrix design can be translated to repetitive control loop shaping filter design in the frequency domain.

math.OC↗