A machine is a physical system that uses power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecules, such as molecular machines. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors that monitor performance and plan movement, often called mechanical systems.
A flexure bearing is a category of flexure which is engineered to be compliant in one or more angular degrees of freedom. Flexure bearings are often part of compliant mechanisms. Flexure bearings serve much of the same function as conventional bearings or hinges in applications which require angular compliance. However, flexures require no lubrication and exhibit very low or no friction.
A flexure is a flexible element engineered to be compliant in specific degrees of freedom. Flexures are a design feature used by design engineers for providing adjustment or compliance in a design.
A mechanical linkage is an assembly of systems connected to manage forces and movement. The movement of a body, or link, is studied using geometry so the link is considered to be rigid. The connections between links are modeled as providing ideal movement, pure rotation or sliding for example, and are called joints. A linkage modeled as a network of rigid links and ideal joints is called a kinematic chain.
In physics, the degrees of freedom (DOF) of a mechanical system is the number of independent parameters that define its configuration or state. It is important in the analysis of systems of bodies in mechanical engineering, structural engineering, aerospace engineering, robotics, and other fields.
Vibration isolation is the prevention of transmission of vibration from one component of a system to others parts of the same system, as in buildings or mechanical systems. Vibration is undesirable in many domains, primarily engineered systems and habitable spaces, and methods have been developed to prevent the transfer of vibration to such systems. Vibrations propagate via mechanical waves and certain mechanical linkages conduct vibrations more efficiently than others. Passive vibration isolation makes use of materials and mechanical linkages that absorb and damp these mechanical waves. Active vibration isolation involves sensors and actuators that produce disruptive interference that cancels-out incoming vibration.
A parallel manipulator is a mechanical system that uses several computer-controlled serial chains to support a single platform, or end-effector. Perhaps, the best known parallel manipulator is formed from six linear actuators that support a movable base for devices such as flight simulators. This device is called a Stewart platform or the Gough-Stewart platform in recognition of the engineers who first designed and used them.
In classical mechanics, a kinematic pair is a connection between two physical objects that imposes constraints on their relative movement (kinematics). German engineer Franz Reuleaux introduced the kinematic pair as a new approach to the study of machines that provided an advance over the motion of elements consisting of simple machines.
In mechanical engineering, a kinematic chain is an assembly of rigid bodies connected by joints to provide constrained motion that is the mathematical model for a mechanical system. As the word chain suggests, the rigid bodies, or links, are constrained by their connections to other links. An example is the simple open chain formed by links connected in series, like the usual chain, which is the kinematic model for a typical robot manipulator.
In mechanical engineering, a compliant mechanism is a flexible mechanism that achieves force and motion transmission through elastic body deformation. It gains some or all of its motion from the relative flexibility of its members rather than from rigid-body joints alone. These may be monolithic (single-piece) or jointless structures. Some common devices that use compliant mechanisms are backpack latches and paper clips. One of the oldest examples of using compliant structures is the bow and arrow. Compliant mechanisms manufactured in a plane that have motion emerging from said plane are known as lamina emergent mechanisms or LEMs.
In engineering, a mechanism is a device that transforms input forces and movement into a desired set of output forces and movement. Mechanisms generally consist of moving components which may include:
Lamina Emergent Mechanisms are more commonly referred to as "Pop-up Mechanisms" as seen in "pop-up-books". LEM is the technical term of such mechanisms or engineering. LEMs are a subset of compliant mechanisms fabricated from planar materials (lamina) and have motion emerging from the fabrication plane. LEMs use compliance, or the deflection of flexible members to achieve motion.
Larry L. Howell is a professor and Associate Academic Vice President (AAVP) at Brigham Young University (BYU). His research focuses on compliant mechanisms, including origami-inspired mechanisms, microelectromechanical systems, medical devices, space mechanisms, and developable mechanisms. Howell has also conducted research in lamina emergent mechanisms and nanoinjection. He received a bachelor's degree in mechanical engineering from BYU and master's and Ph.D. degrees from Purdue University. His Ph.D. advisor was Ashok Midha, who is regarded as the "Father of Compliant Mechanisms."
Mechanical metamaterials are artificial materials with mechanical properties that are defined by their mesostructure in addition to than their composition. They can be seen as a counterpart to the rather well-known family of optical metamaterials. They are often also termed elastodynamic metamaterials and include acoustic metamaterials as a special case of vanishing shear. Their mechanical properties can be designed to have values which cannot be found in nature.
Kinematics equations are the constraint equations of a mechanical system such as a robot manipulator that define how input movement at one or more joints specifies the configuration of the device, in order to achieve a task position or end-effector location. Kinematics equations are used to analyze and design articulated systems ranging from four-bar linkages to serial and parallel robots.
As humans move through their environment, they must change the stiffness of their joints in order to effectively interact with their surroundings. Stiffness is the degree to a which an object resists deformation when subjected to a known force. This idea is also referred to as impedance, however, sometimes the idea of deformation under a given load is discussed under the term "compliance" which is the opposite of stiffness . In order to effectively interact with their environment, humans must adjust the stiffness of their limbs. This is accomplished via the co-contraction of antagonistic muscle groups.
Sunil K. Agrawal is an Indian roboticist and professor of Fu Foundation School of Engineering and Applied Science with secondary appointment in Rehabilitation and Regenerative Medicine at Columbia University. Agrawal is the author of more than 500 journals, three books, and has 15 U.S. patents.
Alper Erturk is a mechanical engineer and the Woodruff Professor in the George W. Woodruff School of Mechanical Engineering at Georgia Institute of Technology.
Freedom and constraint topologies. is a mechanical design framework developed by Dr. Jonathan B. Hopkins. The framework offers a library of vector spaces with visual representations to guide the analysis and synthesis of flexible systems. Flexible systems are devices, mechanisms, or structures that deform to achieve desired motion such as compliant mechanisms, flexures, soft robots, and mechanical metamaterials.
Mary Irene Frecker is an American mechanical engineer whose research focuses on topology optimization of adaptive structures, compliant mechanisms, and self-folding origami mechanisms, with applications including the design of medical devices. She is a professor of mechanical and biomechanical engineering in the Penn State College of Engineering, Riess Chair of Engineering, head of the mechanical engineering department, and director of the Penn State Center for Biodevices.
