Existing actuators in robotics are noisy, rigid and not very lifelike in their movements. There is a need for actuators in especially limb prosthetics and exoskeletons that are silent, softly moving and preferably operating on low currents. One such solution is the conducting polymers. Textiles are well researched and there is a wide variety of patterning. Even more important is their reproducibility and how easily they are mass-produced. This thesis work combines conducting polymers with textiles to achieve linear textile actuators. The textiles are coated with the conducting polymer Polypyrrole which has the property of volume change, when a voltage is applied and there is a reservoir of ions accessible. The volume change, expansion and contraction, results in a linear actuation. The force and strain are measured while changing different parameters and the results are evaluated in this thesis.

Search and rescue mobile robots have shown great promise and have been under development by the robotics researchers for many years. They are many locomotion methods for different robotic platforms, including legged, wheeled, flying and hybrid. In general, the environment that these robots would operate in is very hazardous and complicated, where wheeled robots will have difficulty physically traversing and where legged robots would need to spend too much time planning their foot placement. Drawing inspiration from biology, we have noticed that the snake is an animal well-suited to complicated, rubble filled environments. A snake’s body has a very simple structure that nevertheless allows the snake to traverse very complex environments smoothly and flexibly using different locomotion modes. Many researchers have developed different kinds of snake robots, but there is still a big discrepancy between the capabilities of current snake robots and natural snakes. Two aspects of this discrepancy are the rigidity of current snake robots, which limit their physical flexibility, and the current techniques for control and motion planning, which are too complicated to apply to these snake robots without a tremendous amount of computation time and expensive hardware. In order to bridge the gap in flexibility, pneumatic soft robotics is a potential good solution. A soft body can absorb the impact forces during the collisions with obstacles, making soft snake robots suitable for unpredictable environments. However, the incorporation of autonomous control in soft mobile robotics has not been achieved yet. One reason for this is the lack of the embeddable flexible soft body sensor technology and portable power sources that would allow soft robotic systems to meet the essential hardware prerequisites of autonomous systems. The infinite degree of freedom and fluid-dynamic effects inherent of soft pneumatics make these systems difficult in terms of modeling, control, and motion planning: techniques generally required for autonomous systems. This dissertation addresses fundamental challenges of soft robotics modeling, control, and motion planning, as well as the challenge of making an effective soft pneumatic snake platform. In my 5 years of PhD work, I have developed four generations of pressure operated WPI soft robotics snakes (SRS), the fastest of which can travel about 220 mm/s, which is around one body per second. In order to make these soft robots autonomous, I first proposed a mathematical dynamical model for the WPI SRS and verified its accuracy through experimentation. Then I designed and fabricated a curvature sensor to be embedded inside each soft actuator to measure their bending angles. The latest WPI SRS is a modularized system which can be scaled up or down depending on the requirements of the task. I also developed and implemented an algorithm which allows this version of the WPI SRS to correct its own locomotion using iterative learning control. Finally, I developed and tested a motion planning and trajectory following algorithm, which allowed the latest WPI SRS to traverse an obstacle filled environment. Future research will focus on motion planning and control of the WPI SRS in outdoor environments utilizing the camera instead of the tracking system. In addition, it is important to investigate optimal control and motion planning strategies for mobile manipulation tasks where the SRS needs to move and manipulate its environment.. Finally, the future work will include the design, control, and motion planning for a soft snake robot where each segment has two degrees-of-freedom, allowing it to lift itself off the ground and traverse complex-real-world environments.

Mechanical compliance will be an essential component for agile robots as they begin to leave the laboratory settings and join our world. The most crucial finding of this dissertation is showing how lessons learned from soft robotics can be adapted into traditional robotics to introduce compliance. Therefore, it presents practical knowledge on how to build soft bodied sensor and actuation modules: first example being soft-bodied curvature sensors. These sensors contain both standard electronic components soldered on flexible PCBs and hyperelastic materials that cover the electronics. They are built by curing multi-material composites inside hyper elastic materials. Then it shows, via precise sensing by using magnets and Hall-effect sensors, how closed-loop control of soft actuation modules can be achieved via proprioceptive feedback. Once curvature sensing idea is verified, the dissertation describes how the same sensing methodology, along with the same multi-material manufacturing technique can be utilized to construct soft bodied tri-axial force sensors. It shows experimentally that these sensors can be used by traditional robotic grippers to increase grasping quality. At this point, I observe that compliance is an important property that robots may utilize for different types of motions. One example being Raibert's 2D hopper mechanism. It uses its leg-spring to store energy while on the ground and release this energy before jumping. I observe that via soft material design, it would be possible to embed compliance directly into the linkage design itself. So I go over the design details of an extremely lightweight compliant five-bar mechanism design that can store energy when compressed via soft ligaments embedded in its joints. I experimentally show that the compliant leg design offers increased efficiency compared to a rigid counterpart. I also utilize the previously mentioned soft bodied force sensors for rapid contact detection (~5-10 Hz) in the hopper test platform. In the end, this thesis connects soft robotics with the traditional body of robotic knowledge in two aspects: a) I show that manufacturing techniques we use for soft bodied sensor/actuator designs can be utilized for creating soft ligaments that add strength and compliance to robot joints; and b) I demonstrate that soft bodied force sensing techniques can be used reliably for robotic contact detection.

The proteins wheat gluten and gelatin were tested for use in biocomposites and soft actuating materials, respectively. In Chapter II, the self-assembly mechanism of trypsin hydrolyzed wheat gluten (THWG) into rigid β-sheets was applied to an aqueous polyvinyl alcohol (PVA) environment. Aqueous PVA was used in order to determine the effects of an aqueous environment other than pure water on THWG self-assembly kinetics and to realize the potential use of THWG as a nanofiller in polymer matrices. THWG was able to self-assemble into anisotropic spikes and agglomerates of spikes called "pompons" through hydrophobic interactions. THWG self-assembly kinetics were retarded in aqueous PVA solutions compared to water, with the highest molecular weight PVA solution showing the slowest self-assembly kinetics. Chapters III and IV explore the potential of gelatin hydrogels for use in soft actuators. A gelatin bilayer system was designed where an active layer swelled more than a passive layer to cause the system to bend/actuate in response to an environmental stimulus. In Chapter III, gelatin layers were chemically crosslinked to different degrees with glutaraldehyde to achieve bilayer bending when placed in water. Curvature of the bilayer system was found to be dependent on the difference in volume swell ratio between the two layers. It was determined that maximum bending occurred when the passive layer swelled to 60% of the swelling of the active layer. Addition of pre-gelatinized starch to the active layer increased layer swelling and bilayer curvature. Treating the starch containing bilayer with -amylase returned the bilayer to its original shape. In Chapter IV, a pH responsive gelatin bilayer was constructed using Type A and Type B gelatin. Type A and Type B gelatin gels had different chemical properties and swelled to different volumes based on the gel solution pH. Bilayers constructed from Type A and Type B gelatin exhibited different degrees of bending when placed in various pH solutions with maximum curvature occuring at pH 10. A cyclic actuator could be formed when the bent bilayers were placed in a minimum of 0.01M NaCl solution. Placement in salt solution resulted in the unbending of the bilayer. Overall, this work demonstrated the various applications of proteins as functional and green materials. / Doctor of Philosophy / The majority of plastics consist of synthetic polymers derived from oil that cannot be broken down by the environment (i.e., not biodegradable). Research is underway to develop sustainable, biodegradable materials. Proteins are a biological polymer that have a wide range of chemical, structural, and functional properties; for this reason they are an excellent source material for use in the design of environmental friendly materials. In Chapter II, the ability of wheat gluten protein to self-assemble into rigid, nanosized structures is used to explore the potential of the protein to be used as a biodegradable nanofiller. A nanofiller is added to various materials in order to improve the overall mechanical properties of the material. Wheat gluten is self-assembled in an aqueous polymer environment. The results show that the polymer environment stunts or slows down the self-assembly rate of the protein compared to a pure water environment. Nanometer sized spikes form in the polymer solutions, indicating wheat gluten could be used as a nanofiller in certain materials. Chapters III and IV explore the use of gelatin proteins for applications in soft robotics. Soft robots and their moveable parts, called soft actuators, are deformable and respond to changes in the environment such as pH, light, temperature, etc. For this reason, soft robots are considerable adaptable compared to traditional rigid robots. Designing a soft actuator from gelatin gels would result in a “smart” material that is biocompatible and biodegradable. A gelatin soft actuator is created using a bilayer design in which one layer of the bilayer swells more than the other layer causing the entire system to bend/actuate. Depending on how the bilayer system was fabricated, bending could be achieved based on stimuli such as the presence of water, the presence of a substrate and enzyme, and changes in pH. Overall, this dissertation demonstrates the extraordinary potential for the use of proteins in designing sustainable materials.

Traditional robots are made from hard materials like hard plastic or metal and consist of regular rigid mechanical parts. Using those parts has some limitations, like limited dexterity and lack of flexibility. Some of these limitations could be avoided through using a compliant material, because it has higher flexibility and dexterity. It is also safer to be in direct contact with humans. This thesis studies soft pneumatic manipulators (SPMs) that move in multi degrees of freedom (MDOF), which makes them able to perform various functions. The study will include designing, fabricating, and testing three different SPMs with different taper angles -- 0^0, 1^0, and 2^0 -- to measure the effect of varying this geometry on the achievable force by the end effector and the range of bending and elongation. Every single SPM consists of three soft pneumatic chambers to reach unlimited points on its workspace through implementing bending and elongating movements. There are a lot of applications for this kind of soft actuators, like rehabilitation, underwater utilizes, and robots for surgery and rescues. Most soft pneumatic actuators provide one kind of movement, for bending, twisting, or elongating. Combining more than one kind of movement in one soft pneumatic actuator provides considerable contributions to the body of research. The SPMs were controlled and tested to evaluate the achieved force and two kinds of movement, bending and elongating range. The results of each module has been compared with the others to determine which actuator has the best performance. Then a force controller was created to maintain the desired force that was achieved by the end effector. The results indicated that the optimal angle of the SPM was 2^0. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Soft robots present the opportunity to extend the capabilities currently demonstrated within the field of robotics. By utilizing primarily soft materials in their construction, soft robots are inherently safe to operate around humans, can handle delicate tasks without advanced controls, and are robust to shocks and impacts during deployment. While proof-of-concept devices have been demonstrated successfully, there remains a need for widely applicable, reliable soft robotic components. This dissertation presents sensors to reliably measure the large deformations exhibited in soft robotic structures and responsive structures enabled by variable stiffness materials that can switch from flexible to stiff on-demand. By characterizing the sensors from the material level, through the manufacturing, to the completed functional device, the fabrication processes can be depended upon to produce sensors with predictable, reliable performance. The sensors were applied to various soft robotic systems through implementation on the surface of the structures to measure surface strains, and embedded in the body of the robot to measure body deformations. The sensory feedback was used to reconstruct the state of and to perform closed-loop control of the soft robot's position. Variable stiffness materials that switch from rigid to soft through application of heat were leveraged to create responsive structures that can be deformed or reconfigured on-demand. This capability is necessary for soft robots to exert load onto the external environment and enables a wider range of interactions with target objects. The work presented in this dissertation furthers the field of soft robotics by illustrating a path toward proven, reliable soft sensors for measuring large strains and variable stiffness materials to create responsive structures.

abstract: This thesis presents the design and testing of a soft robotic device for water utility pipeline inspection. The preliminary findings of this new approach to conventional methods of pipe inspection demonstrate that a soft inflatable robot can successfully traverse the interior space of a range of diameter pipes using pneumatic and without the need to adjust rigid, mechanical components. The robot utilizes inflatable soft actuators with an adjustable radius which, when pressurized, can provide a radial force, effectively anchoring the device in place. Additional soft inflatable actuators translate forces along the center axis of the device which creates forward locomotion when used in conjunction with the radial actuation. Furthermore, a bio-inspired control algorithm for locomotion allows the robot to maneuver through a pipe by mimicking the peristaltic gait of an inchworm. This thesis provides an examination and evaluation of the structure and behavior of the inflatable actuators through computational modeling of the material and design, as well as the experimental data of the forces and displacements generated by the actuators. The theoretical results are contrasted with/against experimental data utilizing a physical prototype of the soft robot. The design is anticipated to enable compliant robots to conform to the space offered to them and overcome occlusions from accumulated solids found in pipes. The intent of the device is to be used for inspecting existing pipelines owned and operated by Salt River Project, a Phoenix-area water and electricity utility provider. / Dissertation/Thesis / Masters Thesis Engineering 2019

abstract: Wearable assistive devices have been greatly improved thanks to advancements made in soft robotics, even creation soft extra arms for paralyzed patients. Grasping remains an active area of research of soft extra limbs. Soft robotics allow the creation of grippers that due to their inherit compliance making them lightweight, safer for human interactions, more robust in unknown environments and simpler to control than their rigid counterparts. A current problem in soft robotics is the lack of seamless integration of soft grippers into wearable devices, which is in part due to the use of elastomeric materials used for the creation of most of these grippers. This work introduces fabric-reinforced textile actuators (FRTA). The selection of materials, design logic of the fabric reinforcement layer and fabrication method are discussed. The relationship between the fabric reinforcement characteristics and the actuator deformation is studied and experimentally verified. The FRTA are made of a combination of a hyper-elastic fabric material with a stiffer fabric reinforcement on top. In this thesis, the design, fabrication, and evaluation of FRTAs are explored. It is shown that by varying the geometry of the reinforcement layer, a variety of motion can be achieve such as axial extension, radial expansion, bending, and twisting along its central axis. Multi-segmented actuators can be created by tailoring different sections of fabric-reinforcements together in order to generate a combination of motions to perform specific tasks. The applicability of this actuators for soft grippers is demonstrated by designing and providing preliminary evaluation of an anthropomorphic soft robotic hand capable of grasping daily living objects of various size and shapes. / Dissertation/Thesis / Masters Thesis Biomedical Engineering 2019

Soft robots allow for almost arbitrary continuous deformation by leveraging the nonlinear, large deformation of soft materials. However, this flexibility of possible motions comes often at the price of restricting a robot for a particular application. Efforts to create modular robots have emerged in recent years, but gaps remain. Here we design four different kinds of modular soft actuators, for bending, linear expansion, bilinear expansion, torsion, such that they all occupy the same 3×3×3in3volume and can be connected to each other to form arbitrary 3D assemblies by coupling to each other mechanically, pneumatically, and electronically. The actuators can be mechanically connected through magnets. Rather than connecting each actuator independently to a pneumatic line, coupling between adjacent actuators allows for a single pressure and vacuum line to run through an assembly, each actuator has its own controller and can be actuated independently by operating two valves which connect the internal chamber of each actuator to the central pressure and vacuum lines. All actuators are connected to the same central controller analogously to the pneumatic coupling. To optimize the designs and assemblies, finite element simulations were used to iterate designs before any fabrication took place. We showcase the modularity of our actuators in three applications: a walking robot, a claw actuator, and a balance plate.<div><br></div><div>Buckling is typically associated with something that occurs in hard materials and is thought of as undesirable, but with soft robotics, buckling can be leveraged to accomplish useful tasks. Buckling experiments involving 1D and 2D buckling as well as applications for the buckling of linear actuators are shown. Buckling patterns in 1D are modified by changing the number of actuators as well as the angles of the boundary condition. By changing the length of the actuator assembly, different buckling modes are observed. By modifying the angle of the fixed ends, different buckling patterns are forced as well. With this knowledge, several applications are demonstrated. A parallel robot is demonstrated that can cause rotation in either direction by modifying the angle at an end to force it to buckle in a certain way. Another application that is demonstrated is the ability to change the overall shape of an assembly by simply modifying the order in which actuation occurs. This demonstrates how something that is typically associated with mechanical failure, buckling, can be used advantageously with soft robotics. Additionally, buckling is demonstrated that is analogous to biological systems.<br></div>

The soft robotics field is developing rapidly and is poised to have a wide impact in a variety of applications. Soft robots have intrinsic compliance, offering a number of benefits as compared to traditional rigid robots. Compliance can provide compatibility with biological systems such as the human body and can provide some benefits for human safety and control. Further research into soft robots can be advanced by further development of pneumatic actuators. Pneumatic actuators are a good fit for exoskeleton robots because of their light weight, small size, and flexible materials. This is because a wearable robot should be human friendly, therefore, it should be light weight, slim, powerful, and simple. In this paper, a novel pneumatic artificial muscle using soft materials including integrated electronics for wearable exoskeletons is proposed. We describe the design, fabrication, and evaluation of the actuator, as well as the manufacturing process used to create it. Compared to traditional pneumatic muscle actuators such as the McKibben actuator and new soft actuators that were recently proposed, the novel actuator overcomes shortcomings of prior work. This is due to the actuator's very high contraction ratio that can be controlled by the manufacturing process. In this paper, we describe the design, fabrication, and evaluation of a novel pneumatic actuator that can accommodate integrated electronics for displacement and pressure measurements used for data analysis and control. The desired performance characteristics for the actuator were 100 ~ 400N at between 35kPa and 105kPa, and upon testing we found almost 120 ~ 300N which confirms that these actuators may be suitable in soft exoskeleton applications with power requirements comparable to rigid exoskeletons. Furthermore, a novel soft pneumatic elbow exoskeleton based on the pneumatic actuator concept and manufacturing process is presented. Each structure is designed and manufactured with all fabric. The distally-worn structure is only 300g, which is light weight for an arm exoskeleton, and the design is simple, leading to a low materials cost. / Master of Science