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This research concerns the design and prototyping of an artificial middle finger, using Shape Memory Alloys (SMAs), PolyLactic Acid (PLA), and other technologies. The design is a biomimicry of the human biological anatomical and muscular systems. After briefly describing the operational features and functioning of natural striated muscles, the docu...
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... for the thumb, the finger or digitus, is composed of three different phalanges, namely the Distal (DP), Intermediate (IP), and Proximal Phalanx (PP), which are joined to the hand via the Metacarpal Bone (MB). The finger has two surfaces, on the bottom and on the top called the palmar and dorsal surface, respectively. See Figure 1, for a visual representation of the finger, as this paragraph explains its different anatomical properties. The phalanx is made of three parts: the base, the shaft and the head. Joints owe their names to the heads of the two phalanges or bones they interconnect: the Distal Interphalangeal (DIP), Proximal Interphalangeal (PIP), and the MetaCarpoPhalangeal (MCP) joints [5]. The muscles that allow the finger to move come from the hand (intrinsic) and the forearm (extrinsic) and insert into the base of the DP or IP. Due to the nature of SMA wires discussed in Section III, this study specifically focuses on extrinsic muscles. Flexion occurs partly due to the Flexor Digitorum tendons. The tendon that reaches the IP is the Superficialis (FDS) tendon, and the DP is the Profundus (FDP) tendon. Extension occurs partly due to the Extensor Tendons. The finger radial movements, abduction and adduction, and cirular movements, circumduction, are controlled by a different set of muscles [5]. Fingers are given motion by striated or skeletal muscles, made of hundreds to thousands of filaments of myofibrils. Myofibrils are composed an intermeshed network of long and fibrous proteins which give the motion to the finger through contraction and strain movement. This contraction is similar to the behavior of SMA wires when ...
Citations
... Finger-wearable haptic devices [72] for multi-DoF cutaneous force feedback driven by four SMA wires for tip-tilt mechanisms and the planar XY spring with four SMA helixes are employed. An artificial finger [73] is a reproduction of the human finger bone and phalangeal structure, actuated by SMA wires. Shape control [74] of compliant, articulated meshes created from shape memory alloy (SMA)-based linear actuators (Active Cells) capable of~25% linear strain was explored as shown in Figure 2c. ...
... Actuator mechanisms (a) flexible pump[52] (b) bi-directional servo[54] (c) linear actuatorsketch[73]. ...
This paper mainly focuses on various types of robots driven or actuated by shape memory alloy (SMA) element in the last decade which has created the potential functionality of SMA in robotics technology, that is classified and discussed. The wide spectrum of increasing use of SMA in the development of robotic systems is due to the increase in the knowledge of handling its functional characteristics such as large actuating force, shape memory effect, and super-elasticity features. These inherent characteristics of SMA can make robotic systems small, flexible, and soft with multi-functions to exhibit different types of moving mechanisms. This article comprehensively investigates three subsections on soft and flexible robots, driving or activating mechanisms, and artificial muscles. Each section provides an insight into literature arranged in chronological order and each piece of literature will be presented with details on its configuration, control, and application.
... Shape memory alloy (SMA) wires are lightweight, noncorrosive, and cost-efficient actuating materials for refined applications in a variety of applications such as prosthetic biomimicry [69], self-expandable surgical implants [70], and aerospace engineering [71]. ...
Abstract Fibers are ubiquitous and usually passive. Optoelectronics realized in a fiber could revolutionize multiple application areas, including biosynthetic and wearable electronics, environmental sensing, and energy harvesting. However, the realization of high-performance electronics in a fiber remains a demanding challenge due to the elusiveness of a material processing strategy that would allow the wrapping of devices made in crystalline semiconductors, such as silicon, into a fiber in an ordered, addressable, and scalable manner. Current fiber-sensor fabrication approaches either are non-scalable or limit the choice of semiconductors to the amorphous ones, such as chalcogenide glasses, inferior to silicon in their electronic performance, resulting in limited bandwidth and sensitivity of such sensors when compared to a standard silicon photodiode. Our group substantiates a universal in-fiber manufacturing of logic circuits and sensory systems analogous to very large-scale integration (VLSI), which enabled the emergence of the modern microprocessor. We develop a versatile hybrid-fabrication methodology that assembles in-fiber material architectures typical to integrated microelectronic devices and systems in silica, silicon, and high-temperature metals. This methodology, dubbed “VLSI for Fibers,” or “VLSI-Fi,” combines 3D printing of preforms, a thermal draw of fibers, and post-draw assembly of fiber-embedded integrated devices by means of material-selective spatially coherent capillary breakup of the fiber cores. We believe that this method will deliver a new class of durable, low cost, pervasive fiber devices, and sensors, enabling integration of fabrics met with human-made objects, such as furniture and apparel, into the Internet of Things (IoT). Furthermore, it will boost innovation in 3D printing, extending the digital manufacturing approach into the nanoelectronics realm.
... On the other hand, we also find robotic arms designed to lift considerable payloads, however comparatively heavy and big [26,83]. In addition, we can find various works on robotic hands, prosthetic and grippers using SMA wires as actuators [43,[88][89][90]. In addition to the aforementioned, multiple general purpose actuators have been developed for micro-positioning applications using advanced control techniques [91][92][93]. ...
In the last decade, the industry of Unmanned Aerial Vehicles (UAV) has gone through immense growth and diversification. Nowadays, we find drone based applications in a wide range of industries, such as infrastructure, agriculture, transport, among others. This phenomenon has generated an increasing interest in the field of aerial manipulation. The implementation of aerial manipulators in the UAV industry could generate a significant increase in possible applications. However, the restriction on available payload is one of the main setbacks of this approach. The impossibility to equip UAVs with heavy dexterous industrial robotic arms has driven the interest in the development of lightweight manipulators suitable for these applications. In the pursuit of providing an alternative lightweight solution for the aerial manipulators, this thesis proposes a lightweight robotic arm actuated by Shape Memory Alloy (SMA) wires. Although SMA wires represent a great alternative to conventional actuators for lightweight applications, they also imply highly nonlinear dynamics, which makes them difficult to control. Seeking to present a solution for the challenging task of controlling SMA wires, this work investigates the implications and advantages of the implementation of state feedback control techniques. The final aim of this study is the experimental implementation of a state feedback control for position regulation of the proposed lightweight robotic arm. Firstly, a mathematical model based on a constitutive model of the SMA wire is developed and experimentally validated. This model describes the dynamics of the proposed lightweight robotic arm from a mechatronics perspective. The proposed robotic arm is tested with three output feedback controllers for angular position control, namely a PID, a Sliding Mode and an Adaptive Controller. The controllers are tested in a MATLAB simulation and finally implemented and experimentally tested in various different scenarios. Following, in order to perform the experimental implementation of a state feedback control technique, a state and unknown input observer is developed. First, a non-switching observable model with unknown input of the proposed robotic arm is derived from the model previously presented. This model takes the martensite fraction rate of the original model as an unknown input, making it possible to eliminate the switching terms in the model. Then, a state and unknown input observer is proposed. This observer is based on the Extended Kalman Filter (EKF) for state estimation and sliding mode approach for unknown input estimation. Sufficient conditions for stability and convergence are established. The observer is tested in a MATLAB simulation and experimentally validated in various different scenarios. Finally, a state feedback control technique is tested in simulation and experimentally implemented for angular position control of the proposed lightweight robotic arm. Specifically, continuous and discrete-time State-Dependent Riccati Equation (SDRE) control laws are derived and implemented. To conclude, a quantitative and qualitative comparative analysis between an output feedback control approach and the implemented state feedback control is carried out under multiple scenarios, including position regulation, position tracking and tracking with changing payloads.
