The Problem of Adhesion Methods and Locomotion Mechanism Development for Wall-Climbing Robots

This review considers a problem in the development of mobile robot adhesion methods with vertical surfaces and the appropriate locomotion mechanism design. The evolution of adhesion methods for wall-climbing robots (based on friction, magnetic forces, air pressure, electrostatic adhesion, molecular forces, rheological properties of fluids and their combinations) and their locomotion principles (wheeled, tracked, walking, sliding framed and hybrid) is studied. Wall-climbing robots are classified according to the applications, adhesion methods and locomotion mechanisms. The advantages and disadvantages of various adhesion methods and locomotion mechanisms are analyzed in terms of mobility, noiselessness, autonomy and energy efficiency. Focus is placed on the physical and technical aspects of the adhesion methods and the possibility of combining adhesion and locomotion methods

An extendible reconfigurable robot based on hot melt adhesives

The ability to physically enlarge one’s own body structures plays an important role in robustness and adaptability of biological systems. It is, however, a significant challenge for robotic systems to autonomously extend their bodies. To address this challenge, this paper presents an approach using Hot Melt Adhesives (HMAs) to assemble and integrate extensions into the robotic body. HMAs are thermoplastics with temperature dependent adhesiveness and bonding strength. We exploit this property of HMAs to connect passive external objects to the robot’s own body structures, and investigate the characteristics of the approach. In a set of elementary configurations, we analyze to which extent a robot can self-reconfigure using the proposed method. We found that the extension limit depends on the mechanical properties of the extension, and the reconfiguration algorithm. A five-axis robot manipulator equipped with specialized HMA handling devices is employed to demonstrate these findings in four experiments. It is shown that the robot can construct and integrate extensions into its own body, which allow it to solve tasks that it could not achieve in its initial configuration.This work was supported by the Swiss National Science Foundation Professorship Grant No. PP00P2123387/1, and the ETH Zurich Research Grant ETH-23-10-3.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s10514-015-9428-

Utilization of Ultrasonic Consolidation in Fabricating Satellite Decking

A fundamental investigation of the use of ultrasonic consolidation (UC) to produce deck panels for small satellites was undertaken. Several fabrication methods for producing structural panels and decking were analyzed. Because of its ability to create aluminum objects in an additive fashion, and at near-room temperatures, UC was found to be a powerful solution for creating highly integrated and modular satellite panels. It also allowed a lightweight and stiff deck to be fabricated without the use of adhesives. A series of experiments were performed to understand the issues associated with creating a sandwich-type structure using UC. The experiments used a peel test apparatus to evaluate the bond strength for various geometric configurations and materials. Aluminum 3003 was chosen as the sole material constituting the deck panel. The honeycomb lattice was found to offer the best core configuration due to its ability to resist vibration from the sonotrode and provide adequate support for pressure induced by the sonotrode. Support materials for enhancing the bonding of the facings to the core were investigated but did not lead to implementation. A CAD model was created to integrate the honeycomb core, facings, and modular bolt pattern into the ultrasonically consolidated structure. The model was used to develop a build procedure for fabricating the deck on the UC machine. A finite element analysis was performed that used an equivalent properties method to represent the deck. The stiffness of a prototype deck was evaluated in a three-point bending test and the results were found to correlate with the finite element model. A sine sweep vibration test was then performed on the prototype deck panel to measure its natural frequencies. Finally, a case study was performed on a deck built for the TOROID spacecraft. A final deck panel was designed using the results from the prototype. The deck included the USUSat bolt pattern, vented honeycomb, and a reinforced rim. The cost and benefits of the final deck panel versus traditional fabrication methods were outlined

Design, Manufacturing, and Locomotion Studies of Ambulatory Micro-Robots

Biological research over the past several decades has elucidated some of the mechanisms behind highly mobile, efficient, and robust locomotion in insects such as the cockroach. Roboticists have used this information to create biologically-inspired machines capable of running, jumping, and climbing robustly over a variety of terrains. To date, little work has been done to develop an at-scale insect-inspired robot capable of similar feats, due to limitations in fabrication, actuation, and electronics integration at small scales. This thesis addresses these challenges, focusing on the mechanical design and fabrication of a sub-2g walking robot, the Harvard Ambulatory MicroRobot (HAMR). The development of HAMR includes modeling and parameter selection for a two degree of freedom leg powertrain that enables locomotion. In addition, a design inspired by pop-up books that enables fast and repeatable assembly of the miniature walking robot is presented. Finally, a method to drive HAMR resulting in speeds up to 37cm/s is presented, along with simple control schemes.Engineering and Applied Science

Evaluation of Advanced Composite Structures Technologies for Application to NASA's Vision for Space Exploration

AS&M performed a broad assessment survey and study to establish the potential composite materials and structures applications and benefits to the Constellation Program Elements. Trade studies were performed on selected elements to determine the potential weight or performance payoff from use of composites. Weight predictions were made for liquid hydrogen and oxygen tanks, interstage cylindrical shell, lunar surface access module, ascent module liquid methane tank, and lunar surface manipulator. A key part of this study was the evaluation of 88 different composite technologies to establish their criticality to applications for the Constellation Program. The overall outcome of this study shows that composites are viable structural materials which offer from 20% to 40% weight savings for many of the structural components that make up the Major Elements of the Constellation Program. NASA investment in advancing composite technologies for space structural applications is an investment in America's Space Exploration Program

A Study on Phase-Changing Materials for Controllable Stiffness in Robotic Joints

This paper studies the viability of using a class of phase-changing materials for the design of controlled variable stiffness robotic joints which enable the design of robots that can operate in confined spaces. In such environments, robots need to be able to navigate in proximity or while in contact with their environment to reach one or more manipulated target. Joints with controllable stiffness can substantially enhance functionality of this class of robots where relatively higher joint stiffness is required to support the robot weight against gravity and low stiffness is desired when operating in complex or delicate environments. The research work presented in this paper focuses on examining thermorheological fluids (TRF) to design and manufacture thermally controlled variable stiffness joints. Two phase-changing materials are considered in the study: low-melting-point solder and hot-melt adhesive. Both materials are embedded in a custom designed joint fabricated using 3D printing and silicone casting. Joint stiffness was investigated with both materials and reported here. The results shows that the proposed variable stiffness joints with TRF achieve wide ranges of load-deflection ratio varying between 0.05 N/mm (when thermally activated) to about 10 N/mm (in bonding state). On average, the joint can withstand 20 times its total weight when in the bonding state. Design challenges and durability of TRF-based joints are discussed

Enabling technologies for precise aerial manufacturing with unmanned aerial vehicles

The construction industry is currently experiencing a revolution with automation techniques such as additive manufacturing and robot-enabled construction. Additive Manufacturing (AM) is a key technology that can o er productivity improvement in the construction industry by means of o -site prefabrication and on-site construction with automated systems. The key bene t is that building elements can be fabricated with less materials and higher design freedom compared to traditional manual methods. O -site prefabrication with AM has been investigated for some time already, but it has limitations in terms of logistical issues of components transportation and due to its lack of design exibility on-site. On-site construction with automated systems, such as static gantry systems and mobile ground robots performing AM tasks, can o er additional bene ts over o -site prefabrication, but it needs further research before it will become practical and economical. Ground-based automated construction systems also have the limitation that they cannot extend the construction envelope beyond their physical size. The solution of using aerial robots to liberate the process from the constrained construction envelope has been suggested, albeit with technological challenges including precision of operation, uncertainty in environmental interaction and energy e ciency. This thesis investigates methods of precise manufacturing with aerial robots. In particular, this work focuses on stabilisation mechanisms and origami-based structural elements that allow aerial robots to operate in challenging environments. An integrated aerial self-aligning delta manipulator has been utilised to increase the positioning accuracy of the aerial robots, and a Material Extrusion (ME) process has been developed for Aerial Additive Manufacturing (AAM). A 28-layer tower has been additively manufactured by aerial robots to demonstrate the feasibility of AAM. Rotorigami and a bioinspired landing mechanism demonstrate their abilities to overcome uncertainty in environmental interaction with impact protection capabilities and improved robustness for UAV. Design principles using tensile anchoring methods have been explored, enabling low-power operation and explores possibility of low-power aerial stabilisation. The results demonstrate that precise aerial manufacturing needs to consider not only just the robotic aspects, such as ight control algorithms and mechatronics, but also material behaviour and environmental interaction as factors for its success.Open Acces

Switchable and Memorable Adhesion of Gold-Coated Microspheres with Electrochemical Modulation

Switchable adhesives using stimuli-responsive systems have many applications, including transfer printing, climbing robots, and gripping in pick and place processes. Among these adhesives, electroadhesive surface can spontaneously adjust their adhesion in response to an external electric field. However, electroadhesives usually need high voltage (e.g. kV) and the adhesion disappears upon turning off the signal. These limitations make them complicated and costly. In this research, we demonstrated a gold-coated silica microsphere (GCSM) with highly switchable and memorable adhesion triggered by a relatively small voltage (<30 V). In the experiment, a silica microsphere with a diameter of 15 μm was glued to a tipless atomic force microscope (AFM) cantilever. The nanoscale thick gold coating was sprayed on the surface of the microsphere by a sputter coater. AFM was used to explore the tunable adhesion with an external voltage at different relative humidity (RH). The results revealed that when applying a positive electrical bias at high RH, the adhesive force increased dramatically while it decreased to almost zero after applying a negative potential. Even if the bias was turned off, the adhesive force state could still be kept and erased on demand by simply applying a negative voltage. The adhesive force can be altered repeatedly by an alternative electrical bias. This adhesion modulated by the external electrical signals is attributed to the electrochemical effect of the nanoscale-thick gold coating, where an oxide layer can be formed and thus becomes positively charged when applying a positive voltage, and counter electric field cancel out the applied negative voltage to decrease the adhesion force

Aeronautical engineering. A continuing bibliography with indexes, supplement 102

This bibliography lists 326 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1978

Phase Change Materials for Controllable Stiffness of Robotic Joints

Snake-like manipulators are well suited for operation in restricted and confined environments where the manipulator body can bend around obstacles to place an end effector at a difficult to access location. They require high stiffness when self-supporting weight against gravity and undertake precision manipulation task, but also require soft properties when operating in complex and delicate environments. A controllable stiffness manipulator has the potential to meet the application demands as it can switch between rigid and soft state. This thesis experimentally investigates the properties of four materials, (low melting point solder, hot-melt adhesive, low melting point alloy and granular material) as candidates for mechanically altering the stiffness of the joints/modules in snake-like manipulators. These materials were evaluated for bonding strength, repeatability, and activation time. Modules for a snake-like manipulator were fabricated using 3D printing and silicone casting techniques including, for the first time, variable stiffness joints that use hot-melt adhesive and low melting point alloy. These modules were evaluated for stiffness properties and low melting point solder based module was found to achieve a stiffness change 150X greater than the state of the art granular material approach. In addition, the proposed modules were able to support 25X of their own weight