A passive T/V-beam absorber architecture for single-axis experimental hand tremor attenuation

Hand tremor is a debilitating motor symptom associated with neurological disorders such as Parkinson’s disease and essential tremor (ET). This study presents the design, parameter tuning, and experimental evaluation of a passive mechanical absorber for tremor attenuation based on T- and V-beam configurations. The proposed device is described as an multi-degree-of-freedom- capable architecture because its geometry can accommodate absorber branches oriented in more than one direction; however, the present experimental validation was conducted using a single- axis, 1-DOF mannequin-based tremor simulator. Therefore, the reported data validate single- axis attenuation only and should not be interpreted as full multidirectional wrist validation. The system operates without external power and is intended as a simple passive alternative to active tremor-suppression devices. Experimental validation demonstrated a reduction of up to 85% in steady-state peak-to-peak displacement relative to the uncontrolled condition. The investigated frequency range was 3.0–6.5 Hz, selected because it overlaps the 4–6 Hz range often reported for Parkinsonian rest tremor and extends into the lower-to-mid range commonly observed in ET dur- ing postural or kinetic tasks. Key design parameters, including absorber mass, equivalent stiffness, beam-position geometry, and actuator configuration, were selected using a constrained parametric tuning procedure rather than an unconstrained global optimization. Frequency-domain metrics, including power spectral density and transmissibility, are defined to complement the time-domain amplitude-reduction metric and to verify attenuation at the dominant excitation frequency. The results suggest that the double V-beam configuration provides stronger single-axis attenuation than the single-actuator configuration and supports further development toward wearable tremor- management applications. T able of abbreviations and nomenclature Abbreviation/Notation Definition m1 Equivalent mass of the primary mannequin-arm system m2 Absorber mass mu = m2/m1 Absorber-to-primary mass ratio x1(t) Primary-system displacement measured at the mannequin hand/finger x2(t) Absorber displacement relative to the primary system c1 Equivalent damping coefficient of the primary system c2 Equivalent damping coefficient of the absorber k1 Equivalent stiffness of the primary mannequin-arm system k2 Nominal absorber stiffness used in the tuning tables © 2026 The Author(s). Published on behalf of Institute of Physics and Engineering in Medicine by IOP Publishing Ltd. Med. Eng. Phys. 147 (2026) 065010 M Shah et al k_eff Effective absorber stiffness after geometric projection of the T- or V-beam layout f Excitation or target tremor frequency f _n Natural frequency of the tuned absorber Omega = 2∗pi∗f Angular excitation frequency Omega_n = 2∗pi∗f _n Absorber natural angular frequency r = omega/omega_n Frequency ratio between excitation and absorber natural frequency a_x Horizontal beam-position or displacement parameter used to tune the absorber geometry a_y V ertical beam-position or displacement parameter; fixed at 19.05 mm in the present tests Theta V-beam angle used to modify stiffness projection and frequency tuning A0 Steady-state peak-to-peak displacement amplitude without absorber Ac Steady-state peak-to-peak displacement amplitude with absorber R_PP Amplitude-reduction metric, R_A = (1-Ac/A0)∗100% S_xx(f ) Power spectral density of the measured displacement signal T(f ) Displacement transmissibility, defined as controlled response over uncontrolled response at frequency f