Applications where peak loads appear every so often would highly benefit from actuators of which the torque can be boosted by an elastic element like a spring. This paper provides a design and validation of a fully mechanical torqueboosting elastic actuator that can accumulate energy within its springs, and release this energy in the form of an additional torque once it senses that the output torque coming from the motor is insufficient. A prototype was manufactured and its performance was validated by measuring the input and output torques during the loading of the springs and the releasing of the energy. Releasing the energy from the springs increased the output torque with 44.7% (from 159Nmm to 230Nmm). However, it was measured that the efficiency of the mechanism averaged around 19.4%, meaning that, even after a torque boost, the mechanism loses torque overall. Nevertheless, the mechanism could accumulate energy, put this energy aside by decoupling itself from the main driveshaft, sense a deficiency of output torque, and release the stored energy in the form of a torque. Therefore, all functional requirements were met. Further research should prove to what extend the performance based criteria can be reached by improving the efficiency of the design.

This study aimed to design and validate a novel laparoscopic grasper as part of the Adlap project, which seeks to develop a versatile modular laparoscopy robot platform with reusable instruments. The main goal was to create an end effector grasper that amplifies pinching force in two stages: a low transmission Phase 1 and a high transmission Phase 2. This approach reduces the force required on the tension rod, thereby minimizing wear on the internal mechanism of the SATA LRS articulation mechanism. Additionally, the study aimed to incorporate a mechanical force-adaptive phase controller, eliminating the need for separate instruments by combining the functions of a low-force tissue grasper and a high-force needle holder. Two prototypes were developed at a 3:1 scale: the Rigid Concept and the Compliant Concept, each utilizing different mechanisms based on the force amplification properties of a wedge. The Rigid Concept featured a 3D-printed housing with all-metal internal components, achieving a Phase 1 transmission value of 0.33 and a Phase 2 transmission value of 0.45, resulting in a force amplification ratio of 1.34. Efficiency during Phase 1 was measured at 66%, while the phase-switching efficiency was 57%. These results suggest that the design successfully met its goals, with potential for further optimization with only minor adjustments. Integrating this compact mechanism offers significant advantages for both robotic operation and manual surgery. While the Compliant Concept showed no force amplification during testing, it theoretically offers a simpler manufacturing process and holds promise for future improvements. The study indicates that the Rigid Concept has significant potential to advance laparoscopic surgery, enhancing instrument reliability, surgical efficiency, and patient outcomes.

The increasing demand for enhanced performance in cutting-edge technology has fueled extensive research in engineering materials. Thanks to their unique mechanical properties, engineered materials have been used to manipulate the propagation of acoustic and elastic waves. The literature review primarily focuses on state-of-the-art Locally Resonant Mechanical Metamaterials (LRMMs), designed for vibration isolation by utilizing the principles of local resonances. It explores their working principles and performance in terms of bandgap tunability, aiming to get a better understanding of the available designs and identify their limitations, with the goal of enhancing the performance and applicability of this concept. Locally resonant mechanical metamaterials in this work are classified as passive or active materials based on their ability to alter the range of band gaps during operation. Passive LRMMs can effectively isolate constant vibrations in specific regions where the band gap remains fixed. However, they are unable to attenuate frequencies that lie outside the fixed bandgap range. Active LRMMs, on the other hand, can dynamically alter the band gaps during operation through external stimuli or integrated actuation. The applicability and tunability of band gaps in large lattices are the main limitations of the LRMMs reported in the literature. Moreover, the designs aimed at achieving low-frequency band gaps are often complex and challenging to realize. Additionally, the actuation principles used to maintain design functionality significantly contribute to these limitations, as nearly all reported active LRMM designs rely on either complex or impractical actuation mechanisms. This research work proposes a tunable vibration isolation system based on locally resonant mechanical metamaterials. The system consists of four unit cells capable of altering the bandgap across a wide range of frequencies by adjusting the stiffness of the resonators. It operates by applying global pres training to the lattice, which in turn compresses the resonators through the other masses in each unit cell, reducing their effective stiffness. The FEM resonator stiffness measurements revealed a reduction in the stiffness, which remains positive up to an applied strain of 0.72%. Specifically, the resonator stiffness decreased from 287.3 N/m at the initial state to 188.8 N/m at a strain of 0.36%, and further decreased to 74.1 N/m at 0.72%. At a higher applied strain of 1.09%, the stiffness became negative, reaching approximately -213.8 N/m and continuing to decrease with greater strain values. The transmissibility simulations demonstrated a wide tunability range for the formulated bandgap, confirming the effectiveness of the proposed design in altering the bandgap. The design was realized using Fused Deposition Modeling (FDM). Experimental results supported the modeling findings, with the bandgap shifting from an initial range of 77.14 Hz to 99.11 Hz to a wider range of 69.71 Hz to 97.47 Hz under a pre-applied strain of 0.54% on a lattice of four unit cells. These findings highlight the capability of the proposed lattice design to shift the bandgap to a lower frequency range.