https://scholar.dgist.ac.kr/handle/20.500.11750/197 Thu, 05 Nov 2026 11:38:17 GMT 2026-11-05T11:38:17Z https://scholar.dgist.ac.kr/handle/20.500.11750/61063 Title: High-Performance Interaction Force Control: A Review of Actuator Impedance and Observer-Based Strategies Author(s): Kangwagye, Samuel; Lee, Chan; Oh, Sehoon Abstract: This paper presents a structured review of interaction force control in robotics, approached from the perspective of mechanical impedance and actuator characteristics. We classify actuators into three types, i.e., Type I: rigid actuators with direct force sensing, Type II: compliant actuators with elastic elements, and Type III: low-impedance actuators with model-based estimation. We further analyze how their inherent mechanical impedance constrains achievable performance. For each type, advanced observer-based control methodologies are introduced to mitigate limitations such as sensor drift, backlash, and model dependence. These include the Reduced-Order Multisensor-Based Force Observer (RMFOB) for drift compensation, the Transmission Force Observer (TFOB) for backlash-robust SEA torque estimation, and Frequency-Shaped Impedance Control (FSIC) for friction-robust model-based actuation. Experimental results across different actuator types verify improvements in transparency, stability, and impedance fidelity. In this review, we systematically link actuator properties with control strategies to provide a unified framework that bridges hardware constraints and control design. In the end, this offers practical guidance for next-generation applications in physical Human-Robot Interaction (pHRI), rehabilitation, and dynamic locomotion. Wed, 31 Dec 2025 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/61063 2025-12-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/61020 Title: Data-driven disturbance compensation for core-type linear motors using TISO-GPR integrated with disturbance observers Author(s): Jung, Hanul; Yeo, Hoyeong; Chang, Hamin; Oh, Sehoon Abstract: An integrated control structure that combines Gaussian process regression (GPR) and a disturbance observer (DOB) is proposed for a core-type linear motor that is affected by patterned disturbance and model mismatch. The conventional controller is a DOB-based feedforward/feedback structure, and the compensation performance is limited by the fixed bandwidth of the Q-filter and the estimation bias that appears under model uncertainty. In addition, the effective frequency is shifted by the motion velocity, and disturbance rejection is degraded under a fixed-bandwidth design. A two-input single-output GPR (TISO-GPR) that uses the position and the velocity as inputs is designed to model a lumped disturbance. A periodic kernel is applied on the position axis to represent the spatial period, and a kernel that reflects the velocity-dependent disturbance component is applied on the velocity axis, where the spatial period is fixed by the device geometry and consistent prediction on the position axis is enabled beyond the training range. The disturbance estimated by the DOB is used for training, and the posterior mean estimate is used as the compensation signal in the feedback loop, which is inserted as an internal feedback compensation signal within the DOB-based structure. A time-domain analysis shows that the compensation is bounded and that a small-gain condition guarantees BIBO stability. Experiments confirm that the proposed method improves the tracking performance and robustness. Fri, 31 Jul 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/61020 2026-07-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60986 Title: Robust DOB design for asymmetric LPV hybrid gantry systems based on mode decomposition and nominal model selection Author(s): Jung, Hanul; Yoon, Jegwon; Kong, Taejune; Oh, Sehoon Abstract: This paper presents a formalized framework for the design and verification of a disturbance observer (DOB) applied to a hybrid gantry stage with actuator asymmetry and payload-dependent LPV characteristics. The system consists of a rigid actuator and a series elastic actuator (SEA) arranged in parallel along the Yaxis, and an X-axis actuator that modifies payload distribution. Four payload configurations are considered, and frequency responses are analyzed to characterize mechanical coupling via Relative Gain Array (RGA). Canonical Polyadic Decomposition (CPD) is applied to derive transformation matrices for dynamic decoupling. The procedure sequentially integrates nominal model selection and DOB bandwidth determination in the transformed coordinates, followed by robust stability validation under varying operating conditions. The proposed framework provides a structured design procedure for LTI-based DOB implementation in asymmetric LPV MIMO systems. Mon, 31 Aug 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60986 2026-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60614 Title: Nut-Driven Transmission Force Controllable Motion Platform for Suppressing Low-Frequency and Impulsive Base Disturbances Author(s): Cheon, Dasol; Oh, Sehoon Abstract: This article proposes a transmission-force controllable actuator (TFCA) for vibration suppression in linear motion platforms. Unlike conventional screw-driven systems, the nut-driven TFCA integrates a compliant spring and encoder to measure and control the transmission force in real time, thereby reducing reflected inertia, increasing stiffness, and enabling rapid response to external disturbances. Dynamic models were derived, and two control strategies-acceleration-based vibration suppression control (AVSC) and transmission-force and ACSC (TAVSC)-were implemented. Experiments using a base-shaker setup evaluated three scenarios: back-drivability, impulse disturbance, and multisine excitation (0.1-100 Hz). Results show that TAVSC reduced acceleration and jerk by over 50% in the time domain and achieved more than 90% suppression in the 0.5-8 Hz band, while AVSC exhibited only marginal improvement. Under multisine excitation, TAVSC maintained more than 5 dB suppression across the spectrum and 86% reduction in the 0.5-8 Hz band. These findings confirm that transmission-force feedback substantially improves vibration suppression against impulsive and low-frequency base disturbances, demonstrating the potential of TFCA for applications such as ambulance stretchers and human-sensitive transport systems. Mon, 31 Aug 2026 15:00:00 GMT https://scholar.dgist.ac.kr/handle/20.500.11750/60614 2026-08-31T15:00:00Z