SUMMARYThe fields of modular reconfigurable robotics and programmable matter study how to compose functionally useful systems from configurations of modules. In addition to the external shape of a module configuration, the internal arrangement of modules and bonds between them can greatly impact functionally relevant mechanical properties such as load bearing ability. A fast method to evaluate the mechanical property aids the search for an arrangement of modules achieving a desired mechanical property as the space of possible configurations grows combinatorially. We present a fast approximate method where the bonds between modules are represented with stiffness matrices that are general enough to represent a wide variety of systems and follows the natural modular decomposition of the system. The method includes nonlinear modeling such as anisotropic bonds and properties that vary as components flex. We show that the arrangement of two types of bonds within a programmable matter systems enables programming the apparent elasticity of the structure. We also present a method to experimentally determine the stiffness matrix for chain style reconfigurable robots. The efficacy of applying the method is demonstrated on the CKBot modular robot and two programmable matter systems: the Rubik's snake folding chain toy and a right angle tetrahedron chain called RATChET7mm. By allowing the design space to be rapidly explored we open the door to optimizing modular structures for desired mechanical properties such as enhanced load bearing and robustness.
An energy efficient joint-locking mechanism that works in conjunction with the main actuator of a robot module is presented. The mechanism will enable chain-style modular reconfigurable robots to perform a wide array of tasks such as dynamic motion and bio-inspired locomotion while consuming less power. The design process for developing this mechanism is presented, and analysis is provided. This mechanism is ideal for modular reconfigurable robot systems, but can be modified to suit many applications. A prototype is developed that outperforms comparable devices such as those that utilize piezoelectrics, magnetic particles, and electromagneticallyactuated disc and drum brakes in terms of power consumption and specific torque.
Modular robotic systems can form arbitrary shapes that best suit task requirements. Such a system comprised of microscale components could form reconfigurable microstructures or high resolution physical prototypes. This paper presents methods aimed at miniaturization of this programmable matter system towards the millimeter scale or smaller. The Right Angle Tetrahedron Chain Externally-actuated Testbed (RATChET) can be folded into arbitrary 3D shapes. The tetrahedron shaped modules are designed to have limited complexity and employ technologies which can be realized at the microscale. The tools developed to design the module’s compliant mechanism can be used to develop small scale modules in the future. Experiments with centimeter scale modules demonstrate that an external actuator can fold a chain of right angle tetrahedrons into 3D shapes. If given the fold pattern to make a shape, a simulator determines the motion sequence for the 2DOF external actuator to fold that pattern.
PurposeThe recent coronavirus pandemic created uncertainty across most markets. This has resulted in many valuations being reported with caveats warning that they are uncertain. However, many valuers and their clients remain unclear as to what these warnings are supposed to convey and why they are required by many valuation standards, including the International Valuation Standards. The purpose of this paper is to explain how recognition of the need for uncertainty disclosures has developed over the past 25 years and how such disclosures can enhance overall trust in valuation.Design/methodology/approachThe author has been involved in the development of the guidance issued by both the International Valuation Standards Council and Royal Institution of Chartered Surveyors, which included extensive consultation with financial regulators and valuation users alike. He has also examined the wider economic theories of risk and uncertainty and how these need to be clearly distinguished in valuations.FindingsThis paper identifies the situations under which valuation uncertainty can occur, and steps that a valuer can follow to determine whether it is sufficiently material to require an appropriate caveat to be issued alongside the valuation. It also examines the merits of different ways in which material uncertainty can be disclosed.Practical implicationsThe paper should provide valuers with a better understanding of the reason why uncertainty disclosures are required and the circumstances in which they are required. It also provides principles to help them formulate disclosures that are appropriate in different circumstances.Originality/valueThis is an abridged version of a Valuers' Briefing “Valuation Uncertainty – Reporting the unknowable” by the author and published as either an eBook or paperback available from Amazon.
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