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Passive Dynamics
Passive dynamics refers to the dynamical behavior of actuators, robots, or organisms when not drawing energy from a supply (e.g., batteries, fuel, ATP). Depending on the application, considering or altering the passive dynamics of a powered system can have drastic effects on performance, particularly energy economy, stability, and task bandwidth. Devices using no power source are considered "passive", and their behavior is fully described by their passive dynamics. In some fields of robotics (legged robotics in particular), design and more relaxed control of passive dynamics has become a complementary (or even alternative) approach to joint-positioning control methods developed through the 20th century. Additionally, the passive dynamics of animals have been of interest to biomechanists and integrative biologists, as these dynamics often underlie biological motions and couple with neuromechanical control. Particularly relevant fields for investigating and engineering pass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Actuator
An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover". An actuator requires a control device (controlled by control signal) and a source of energy. The control signal is relatively low energy and may be electric voltage or current, pneumatic, or hydraulic fluid pressure, or even human power. Its main energy source may be an electric current, hydraulic pressure, or pneumatic pressure. The Control device is usually a valve. When it receives a control signal, an actuator responds by converting the source's energy into mechanical motion. In the ''electric'', ''hydraulic'', and ''pneumatic'' sense, it is a form of automation or automatic control. History The history of the pneumatic actuation system and the hydraulic actuation system dates to around the time of World War II (1938). It was first created by Xhiter Anckeleman who used his knowledge of engines an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Simon Fraser University
Simon Fraser University (SFU) is a public research university in British Columbia, Canada, with three campuses, all in Greater Vancouver: Burnaby (main campus), Surrey, and Vancouver. The main Burnaby campus on Burnaby Mountain, located from downtown Vancouver, was established in 1965 and comprises more than 30,000 students and 160,000 alumni. The university was created in an effort to expand higher education across Canada. SFU is a member of multiple national and international higher education associations, including the Association of Commonwealth Universities, International Association of Universities, and Universities Canada. SFU has also partnered with other universities and agencies to operate joint research facilities such as the TRIUMF, Canada's national laboratory for particle and nuclear physics, which houses the world's largest cyclotron, and Bamfield Marine Station, a major centre for teaching and research in marine biology. Undergraduate and graduate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Evolutionary Robotics
Evolutionary robotics is an embodied approach to Artificial Intelligence (AI) in which robots are automatically designed using Darwinian principles of natural selection. The design of a robot, or a subsystem of a robot such as a neural controller, is optimized against a behavioral goal (e.g. run as fast as possible). Usually, designs are evaluated in simulations as fabricating thousands or millions of designs and testing them in the real world is prohibitively expensive in terms of time, money, and safety. An evolutionary robotics experiment starts with a population of randomly generated robot designs. The worst performing designs are discarded and replaced with mutations and/or combinations of the better designs. This evolutionary algorithm continues until a prespecified amount of time elapses or some target performance metric is surpassed. Evolutionary robotics methods are particularly useful for engineering machines that must operate in environments in which humans have limit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Underactuation
Underactuation is a technical term used in robotics and control theory to describe mechanical systems that cannot be commanded to follow arbitrary trajectories in configuration space. This condition can occur for a number of reasons, the simplest of which is when the system has a lower number of actuators than degrees of freedom. In this case, the system is said to be ''trivially underactuated''. The class of underactuated mechanical systems is very rich and includes such diverse members as automobiles, airplanes, and even animals. Definition To understand the mathematical conditions which lead to underactuation, one must examine the dynamics that govern the systems in question. Newton's laws of motion dictate that the dynamics of mechanical systems are inherently second order. In general, these dynamics can be described by a second order differential equation: \ddot = f(q,\dot,u,t) Where: q \in \mathbb^n is the position state vector u \in \mathbb^m is the vector of co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Crisis (dynamical Systems)
In applied mathematics and astrodynamics, in the theory of dynamical systems, a crisis is the sudden appearance or disappearance of a strange attractor as the parameters of a dynamical system are varied. This global bifurcation occurs when a chaotic attractor comes into contact with an unstable periodic orbit or its stable manifold. As the orbit approaches the unstable orbit it will diverge away from the previous attractor, leading to a qualitatively different behaviour. Crises can produce intermittent behaviour. Grebogi, Ott, Romeiras, and Yorke distinguished between three types of crises: * The first type, a boundary or an exterior crisis, the attractor is suddenly destroyed as the parameters are varied. In the postbifurcation state the motion is transiently chaotic, moving chaotically along the former attractor before being attracted to a fixed point, periodic orbit, quasiperiodic orbit, another strange attractor, or diverging to infinity. * In the second type of crisis, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |