At this moment there are more than 150 different designs of CMMA in existence. To aid the designer to develop a new or improved CMMA or choose what the design to use, a classification system is developed during the literature research. It is based on the geometrical advantage (GA) of the CMMA, and on the input and output port motion paths. Their properties resulted in 5 different classes, with a total of 50+ CMMA designs. The mechanical efficientcy (ME) of CMMA or compliant mechanisms in general can be non- optimal because of the elastic energy storage during motion. A technique called static balancing, can be applied to improve the efficiency of the device. A new way to apply the static balancing, without manual preloading, is developed for a straight-line micro mechanism. This technique allows applying static balancing on batch scale that was not available before. A MEMS design is developed and a prototype fabricated and tested. Another step closer in creating statically balanced for compliant mechanical micro motion amplifiers.

Duchenne Muscular Dystrophy (DMD) patients suffer from a severe form of progressive muscular weakness. Consequently, as the disease progresses these patients become more and more dependent on assistive devices for their daily activities. For instance lifting their arms against gravity already becomes challenging. So far, a considerable amount of effort has been put in the development of assistive devices. However, compensating the weight of the hand remains challenging as the required balancing torques are dependent on the position of the hand and the orientation of the forearm. In this research a solution is proposed to passively compensate the weight of the hand by making use of a simplified torque profile (a constant torque). The effectiveness of this profile was assessed experimentally in a group of healthy subjects. For this the wrist muscle activity required to lift the hand against gravity was measured through surface electromyography, for several types of compensation. From this experiment the conclusion can be drawn that a constant torque profile performs similar to the theoretically ideal type of balancing, showing a similar reduction in the anti-gravity muscle activity. Based on these findings, a mechanism has been developed capable of providing an adjustable constant force, by making use of a combination of positive and negative stiffness springs, for implementation in a wrist support for DMD patients.

The detachment of a product from a suction cup gripper is a challenge that emerged in recent years in the high-speed case packing of packaged food. In this industry suction cups are used to temporarily attach a product to a case packing robot. The detachment of products from the suction cup gripper threatens throughput. In, some cases, the industry notes robots to operate at only 40 picks per minute. This is 30 % of their maximum throughput. This study aims to gain a better understanding of the dynamic grasping strength of suction cups. This was done by reviewing the state-of-the-art from industry and state-of-the-practice from literature. It was found that suction cups are the best overall gripper class, and that actuation time poses the main limiting factor for other grippers to perform well in this industry. Secondly, a six-axis force moment sensor that passes airflow for gripper actuation and without limiting the pull-out load measurement performance was designed, fabricated, and validated. With the current sensor technology, the vacuum hose must be placed over the sensor, leading to the generation of parasitic loads. Passing the airflow through the senor structure is essential to eliminate loads otherwise induced by the stiff vacuum hose. The sensor was designed using strain gauges and a Maltese cross sensor structure. Finite Element Modeling and optimization using sequential quadratic programming was used to determine the dimensions of the sensor. The sensor validation showed a maximum measurement error of 8% in the z direction. Lastly, with the validated sensor, the dynamic grasping strength of compliant and stiff suction cups was measured using motion paths and products that are typically seen in the packaged food industry. For both the stiff and compliant suction cups, the moment around the axis perpendicular to the plane of motion showed to be a leading factor in detachment of a product from a suction cup gripper. The failure of stiff suction cups is explained by impulse loading, this results in peaks in the load in the force in horizontal direction and the moment perpendicular to the plane of motion. For the compliant suction cups, the detachment was found to be caused by accelerating downwards while the product was not in the center of the gripper. These results have led to the recommendation of two gripper designs. The first, is a suction cup-underactuated hybrid gripper. The second design intently provides rotation freedom to reduce the moment loading on the suction cup. The second design requires input-shaping to reduce the vibrations at the end of the motion cycle.

Vibration Energy Harvesting has the potential to become a convenient, sustainable and localized power source for the billions of small electronic devices of the future. One of the most challenging areas within this field is the design of miniaturized generators for power harvesting from human motion. In this thesis, a new strategy, design and prototype are presented for vibration energy harvesting from human motion.

Vibration energy harvesting has proven to be a durable source of energy for a wide variety of applications, however not all of the positions these applications are placed at are suitable for conventional vibration energy harvesting. For some of these applications a frequency up-converted energy harvester could increase the power harvested. These systems are analysed in this thesis project, by first gaining insight in previously performed. After which a new method is designed and modelled. The design was then fabricated and a proof of concept was tested, of which the results are presented in this thesis project report.

Mechanical metamaterials are architected materials with unique properties derived from their internal structure, rather than the material they consist of. Introducing distinct stable states into the material architecture allows the creation of mechanical metamaterials with multiple effective properties that can be altered post-fabrication. So far these so-called reprogrammable mechanical metamaterials have only demonstrated responsive behaviour, where the state of the metamaterial is dictated by the external input, leading to complex actuation and limited functionality. This research introduces a transformative approach to overcome these limitations through state-dependent switching, enabling metamaterials to autonomously determine their state based on internal information. Leveraging internal instabilities in the form of bistable and slender buckling elements, a contactless and tessellatable 3D unit cell design that can switch between positive and negative Poisson's ratios upon a specified displacement threshold is introduced. State transition occurs based on internal state information, rather than the external input, enabling adaptive behaviour. Both, Finite Element Analysis (FEA) simulations and experimental validation demonstrate the ability of the unit cell to switch between positive and negative Poisson's ratio under the same repeated input. Preliminary FEA simulations further suggest that through the tessellation of this innovative unit cell, the adaptive behaviour can be exploited to create mechanical metamaterials capable of adaptive shape morphing and repeatable counting abilities.

This thesis aims to solve the problems and fabricate fully inkjet-printed dielectric elastomer actuators with silver electrodes and a PDMS middle layer. First, a conductive silver electrode is printed on a coated PET substrate, followed by a printing of the dielectric elastomer middle layer to cover the bottom electrode. Then, the top silver layer is printed on the PDMS to achieve the top electrode. The problems intended to be solved in this work include printing the dielectric elastomer middle layer, treating the PDMS layer, the significant surface cracking, and the non-conductivity of the top electrode. During the fabrication process, different concentrations of PDMS solution are tested printing. Observations on these printed samples are made to validate the most suitable printing solution and printing process/settings. Different surface treatment cycles for the PDMS layer are also adopted to determine the most suitable one, what effect is brought to the PDMS layer surface, and how they influence the top electrode. For the fabrication of the top electrodes, experiments are accomplished and repeated, coming with failures, which will be presented and discussed later. Lastly, displacement and frequency response measurements are essential to check the performance of the DEAs, being critical sections of the thesis.

The use of origami-based mechanisms in the engineering field is growing as their advantages are better understood. Origami-based mechanisms have the advantage of being lightweight, compact, and their ability to transform from a flat sheet into complex three-dimensional structures makes them a source of inspiration to meet design challenges. A fold in paper is realized by a localized reduction in thickness, which reduces stiffness. Since most materials do not exhibit this property when folded, other techniques are used to facilitate this stiffness reduction. These include sandwiching a thinner material between rigid facets, or by thinning to create a groove joint (notch joint). The drawbacks of these techniques are that the first technique requires assembly, and the second technique requires complex material removal. Another technique has been proposed to reduce stiffness with simpler manufacturing methods, namely lamina emergent joints. These joints require cutting through the material, which can be done using well-established sheet manufacturing methods, such as laser cutting or stamping. However, the removal of material involves a trade-off between range of motion and stiffness in directions other than the desired bending motion. Initial research indicates that the groove joint is able to maintain the highest stiffness and range of motion, thus outperforming the lamina emergent joint. Therefore, the objective of this paper is to design an improved lamina emergent joint that approaches the performance of the groove joint. This is achieved by quantifying and evaluating the stiffness performance and range of motion of existing lamina emergent joints and then combining them on strong features. Improved designs are proposed that made an approach toward the groove joint and the best design was selected for optimization. The results showed that the selected design was not able to outperform the groove joint on both stiffness and range of motion. However, it was able to achieve similar in-plane shear stiffness and higher torsion stiffness than a groove joint with a lower thickness ratio. However, this also allowed more range of motion for the groove joint. So figuring out this trade-off between stiffness and range of motion is challenging and essential to design suitable joints in the future.

The range of motion of elastic energy sources is limited by the size of its transmission system. To enhance this range of motion without compromising the size, previous research introduced a frequency doubling mechanism with the intention to concatenate these mechanisms. This study serves to achieve higher numbers of frequency multiplication by concatenating up to three frequency doubling mechanisms. A crucial challenge is to reduce the input force required to operate the compliant design, even in the absence of output load, to ensure the output moves twice the distance of the input. The optimization process involved simulations to achieve a near-perfect Geometrical Advantage (G.A.) of 2 while ensuring the highest possible load capacity to minimize force-induced geometrical variations. The optimized mechanism was then statically balanced with buckled beams to minimize the input force of each frequency doubling mechanism. The buckled beams introduced negative stiffness, adding potential energy to counteract forces, and ultimately reducing the input force to approximately 5.3% of the initial force. Three frequency doubling mechanisms were concatenated and experimentally validated, achieving a frequency multiplication of 8. The real prototype demonstrated successful results, although the input force was not entirely eliminated, the desired frequency multiplication was achieved. These results form the basis for a compliant frequency multiplication mechanism, enhancing the range of motion of elastic strain energy sources through the implementation of a compact transmission system.

Building a distributed fluidic actuation system is a challenge due to every actuator needs its own control valve. Due to this, an n by an array of actuators needs n 2 number of valves. A logic network of valves provides a solution by reducing the number of valves needed to operate such distributed fluidic actuation system. These compliant fluidic networks could have a broad application in different fields such as biomedical, microfluidics, or in soft robotics. An example in the biomedical field is for creating an actuated surface that is controlled by a fluidic logic that goes around a hollow organ. This sleeve could provide support to the organ by externally providing actuation. The main goal of the paper is to design a compliant valve that easily could be integrated into a large fluidic logic network, to demonstrate the network a demultiplexer is built. Compliant is defined as soft material (small E modules) with hyperplastic properties. To get a better understanding of what is already done in the field of distributed actuation systems a literature study is conducted. The thesis will provide information on the design steps of creating a valve and how to integrate them in a fluidic network that is a demultiplexer. The operating principle of this valve is that there are 2 channels on top of each other on a 90-degree angle, one channel will be inflated and will choke the other channel. Different valve designs based on this principle have been built and tested using different shapes and combinations of materials. Using FEM software the closing pressure is calculated. After that prototypes have been built and experiments are conducted. During experiments, the pressure drop has been measured in the channel that will be closed. The next step is to understand how these valves operate in a large network. A Simulink model of a demultiplexer has been built, it was shown that 2.4 seconds to inflate an array of 8 small bellow actuators with a stroke of 5 mm. After simulating a demultiplexer is created. Experimental results show that the best-performing valve completely closes a line with a pressure of 12 kPa with an operating pressure of 26 kPa. As a demonstrator of a large-scale network a demultiplexer is built, unfortunately, it did not perform due to manufacturing problems. To answer the main question of this paper a fully functioning logic network has not yet been achieved however, it could be said that this paper has laid a good foundation for further improvement of the creation of a scalable solution for an actuating surface. It also has to be noted that the valve designs that are discussed in this paper operate on an mm scale instead of an cm-scale which is commonly found in the literature.

Mechanical computing systems have historically faced challenges in efficiently integrating computation and memory functions, often leading to complex designs and limited scalability in applications ranging from micro-electromechanical systems (MEMS) to programmable matter. This study aims to address this issue by introducing a mechanical system based on cellular automata (CA) principles, utilizing a bi-threshold tristable mechanism for implementing nonlinear Boolean functions. The system’s design translates Elementary Cellular Automata (ECA) rules, such as Rule 110, into mechanical motion using compliant multistable mechanisms. Finite Element Analysis (FEA) and pseudo-rigid body simulations validate the operational feasibility of this approach. The results confirm the system’s capability to process complex computational tasks by mechanically embodying specific ECA rules. This development marks a step forward in mechanical computing, offering a more integrated approach to computational material design. The research establishes a methodical design approach, enabling the embodiment of a wide range of Elementary Cellular Automata (ECA) rules within the mechanical framework. This approach extends beyond linearly separable Boolean functions, illustrating a significant advancement in mechanical computing capabilities. The findings provide a basis for future work in scaling the system and exploring its applicability in fields such as programmable matter and intelligent mechanical systems.

Micromechanical resonators, which have become feasible due to advanced manufacturing techniques, have shown several interesting phenomena including mode coupling in a range of applications that span metrology and sensing. Conventional fabrication methods of these resonators have been used throughout the field. However, fabrication of micromechanical resonators by femtosecond laser ablation which could accelerate prototyping, access to three dimensional resonators and reduce clean room use, has received little attention. In this study, a protocol for fabricating and measuring laser cut micromechanical resonators using computational analysis and experimental techniques has been developed and validated through comparison with previous works by characterising doubly clamped beam resonators. The fabricated prototype is demonstrated to exhibit autoparametric resonance and coupling showcasing the potential of the new approach in engineering and fast prototyping of coupled micromechanical resonators.

The Netherlands has a severe shortage of care workers. The shortage is expected to increase in the coming years. Care-robots could provide a solution, by taking work out of the hands of the care workers. The potential utility of the care-robot is dependent on the functionality of the gripper. The goal of this study was to design and develop a new gripper for a care-robot, applicable in a care environment. Furthermore, the functional performance of the gripper was to be assessed and evaluated. The new gripper needed to outperform the previous gripper of the robot, named the RPG, in terms of functionality. A new gripper was designed in this study, named the 4FH. The 4FH has four fingers, resembling a human thumb, index, middle and ring finger. Sideways rotation of the thumb allows for two grasping modes, namely a pinch mode and a power grip mode. The 4FH has three DOFs in total. A glove is fitted around the gripper for hygiene. An improvement was made to the 4FH by modifying the shape of the thumb. The improved version is named the 4FH-i. A set of three assessments was drawn up for measuring functional performance of a gripper for a care-robot. The set consists of the the EIT, modified SHAP and modified AHAP. The SHAP and AHAP were modified in this study to make them representative for applications of a care-robot. Both the 4FH and 4FH-i outperformed the RPG on the modified SHAP and on the modified AHAP. All grippers passed the EIT. The results showed a significant increase in grasp stability, comparing the 4FH and 4FH-i to the RPG. The higher scores on the assessments indicated that the 4FH and 4FH-i have improved functional performance compared to the RPG.

Singularity points are causing problems in motion converters. A solution is found and experimentally validated.

The use of elastic frequency multipliers presents the ideal platform to address the coupling between the footprint and range of motion of elastic mechanisms. By transmitting unidirectional into reciprocating motion they efficiently increase the range of motion without a huge compromise in size. In this thesis, an elastic frequency doubler based on an eight-bar mechanism that exploits the displacement around a singularity to double the frequency is presented. Higher frequency multiplications can be achieved by concatenating this mechanism, surpassing previous designs in the literature. To facilitate effective concatenation, criteria for optimization were established and a design study was conducted to determine the optimal geometrical parameters of the mechanism. The utilization of not only the actuation capabilities but simultaneously leveraging the inherently stored strain energy during operation has the potential to serve as the foundation for a novel group of architected materials. The embodiment of both functionalities makes these architected materials highly desirable for control in autonomous robots where, through the exploitation of close synergy and decrease in dissipation, this multifunctionality could increase the efficiency in usage of the usually limited space and available energy.

Vibration energy harvesters have been proposed as a solution to increase the lifetime of wireless and portable medical devices. One example of implantable medical devices for which energy harvesters could be interesting, are pacemakers. With a lifespan of about 6 to 12 years, the battery must be replaced after this period of time. Using an energy harvester instead of a battery is therefore seen as an interesting alternative. However, the human heart rate is usually between 0.6-2Hz and consists of low acceleration peaks (<1g). The use of resonance at low frequency is extremely difficult, especially when the motion amplitude is larger than the device itself. A solution is sought in the non-resonant bistable energy harvesters. When enough force is applied to overcome the potential energy barrier, snap through motion is induced, resulting in a significant increase in power output. However, large threshold accelerations are limiting the usability of these systems. Therefore, stiffness compensation is required. A prototype was fabricated in which buckled flexures were used to add negative stiffness to a piezoelectric cantilever, resulting in a stiffness compensated bistable energy harvester suitable for energy harvesting from low frequency and low force excitations. The dynamical behaviour and practical performance of the prototype was studied in relation to a heartbeat, sawtooth wave and sine waves. The output power of the non-resonant prototype was compared to a resonant device, which in all cases showed that the non-resonant prototype outperformed the resonant device. This shows that stiffness compensated bistable energy harvesters can be used in order to make energy harvesting for low force and low frequency excitations, such as a heartbeat, possible.

In-situ sample holders with double-tilting capabilities are used to insert and position samples inside a transmission electron microscope for dynamic imaging. However, the performance of these sample holders, regarding energy-dispersive X-ray spectroscopy (EDS) analysis, is not on par with their single-tilt counterparts. By analyzing the EDS influences and the tilting mechanism of double-tilt sample holders, the need for a remote-center-of-motion (RCM) mechanism as a tilting mechanism is identified. Because existing RCM mechanism design strategies limit the design flexibility, a novel design strategy is developed. The novel strategy gives more flexibility in terms of the use of space, design for stiffness and it gives variable input/output link rotation ratio functionality. A compliant proof-of-principle mechanism, which is designed using the novel RCM mechanism design strategy, is manufactured to characterize the accuracy, force/displacement behavior and the input/output link rotation ratio. Analytical, numerical and experimental results are compared, and it can be concluded that the compliant RCM mechanism has potential to be used in double-tilt sample holders.

Origami-based mechanisms have emerged as a promising solution for developing locomotion systems. Its light-weight nature, scalability, and possibility for 2D monolithic manufacturing makes origami an attractive option for various applications, such as mobile robots and meta-surfaces. While various types of origami-based locomotion exist, constant-height walking locomotion does not have an origami-based solution yet. To achieve this, we present a 2-DOF crease pattern with two internal vertices and geometric constraints that can perform the required output path. A parametric study performed on the presented pattern reveals many different feasible geometries. Subsequently, these geometries are evaluated based on their capabilities to produce a path with minimized displacement along the Z-direction and minimal change in velocity of the end effector during propulsion. As a demonstration, we then utilized these results to optimize the design of a locomotion system for active surfaces. Finally, the results are verified with experiments using a physical prototype. In conclusion, the analysis of the results provides valuable insights in the behavior of the crease pattern, which can be utilized for designing and optimizing an origami-based locomotion system for other applications with different requirements.

This paper presents a validation of a parametric compliance matrix of a circularly curved leaf flexure (CCLF), which has been obtained using the direct method. This is done for three case studies. In case study one, the compliance matrix of a single flexure is evaluated. The results are compared with the results from a finite element analysis over a range of geometrical parameters. This maps how the geometry of the flexure affects the accuracy of the compliance matrix. It is shown that an increase of both the sweep angle and the height of the flexure show a decrease in the accuracy. Additionally a test setup was built to measure the stiffness of a single flexure to validate the compliance matrix. Furthermore, in case study two and three, the compliance matrices of mechanisms containing multiple flexures in series and parallel are derived with the compliance matrix method, using adjoint transformation matrices. The results are validated by comparison with FEA and measurements from a test setup. A parallel combination of flexures show a decrease in error, when compared to a single flexure.