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Impedance control is an approach to dynamic control relating force and position. It is often used in applications where a manipulator interacts with its environment and the force position relation is of concern. Examples of such applications include humans interacting with robots, where the force produced by the human relates to how fast the robot should move/stop. Simpler control methods, such as position control or torque control, perform poorly when the manipulator experiences contacts. Thus impedance control is commonly used in these settings.
Mechanical impedance is the ratio of force output to motion input. This is analogous to electrical impedance that is the ratio of voltage output to current input (e.g. resistance is voltage divided by current). A "spring constant" defines the force output for a displacement (extension or compression) of the spring. A "damping constant" defines the force output for a velocity input. If we control the impedance of a mechanism, we are controlling the force of resistance to external motions that are imposed by the environment.
Mechanical admittance is the inverse of impedance - it defines the motions that result from a force input. If a mechanism applies a force to the environment, the environment will move, or not move, depending on its properties and the force applied. For example, a marble sitting on a table will react very differently to a given force than will a log floating in a lake.
The key theory behind the method is to treat the environment as an admittance and the manipulator as an impedance. It assumes the postulate that "no controller can make the manipulator appear to the environment as anything other than a physical system."
This rule of thumb can also be stated as: "in the most common case in which the environment is an admittance (e.g. a mass, possibly kinematically constrained) that relation should be an impedance, a function, possibly nonlinear, dynamic, or even discontinuous, specifying the force produced in response to a motion imposed by the environment."[1]
^Hogan, N. (June 6–8, 1984). "Impedance Control: An Approach to Manipulation" (PDF). American Control Conference. pp. 304, 313. Archived (PDF) from the original on December 21, 2021. Retrieved September 19, 2013.{{cite web}}: CS1 maint: date and year (link)
Impedancecontrol is an approach to dynamic control relating force and position. It is often used in applications where a manipulator interacts with its...
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Fiorini, Paolo (November 2017). "Impedancecontrol of series elastic actuators: Passivity and acceleration-based control". Mechatronics. 47: 37–48. doi:10...
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In electromagnetism, the impedance of free space, Z0, is a physical constant relating the magnitudes of the electric and magnetic fields of electromagnetic...
Dielectric spectroscopy (which falls in a subcategory of impedance spectroscopy) measures the dielectric properties of a medium as a function of frequency...
purpose is to optimize power transfer by matching the impedance of the radio to the signal impedance on the feedline to the antenna. Various alternate names...
A line impedance stabilization network (LISN) is a device used in conducted and radiated radio-frequency emission and susceptibility tests, as specified...
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authors first used names like "reflection chart", "circle diagram of impedance", "immittance chart" or "Z-plane chart", early adopters at MIT's Radiation...
p. 90 ff. ISBN 978-0-521-54411-5. Christian Ott (2008). Cartesian ImpedanceControl of Redundant and Flexible-Joint Robots. Springer. p. 23. ISBN 978-3-540-69253-9...
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...
doi:10.1142/S0219843604000058. Dietrich, Alexander (2016). "Whole-Body ImpedanceControl of Wheeled Humanoid Robots". Springer Tracts in Advanced Robotics...
defined as the ratio of the rated impedance of the loudspeaker (usually assumed to be 8 Ω) to the source impedance of the power amplifier. It was originally...
(SWR) is a measure of impedance matching of loads to the characteristic impedance of a transmission line or waveguide. Impedance mismatches result in standing...
its electrical impedance to provide a more ideal source (with a lower output impedance for a voltage buffer or a higher output impedance for a current...
dimensions along their length, giving them a uniform impedance, called the characteristic impedance, to prevent reflections. Types of transmission line...
waves given a specified reference impedance Z0. The reference impedance used is typically the characteristic impedance of a transmission line that's involved...
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voltage from a high output impedance circuit to a second circuit with low input impedance. Directly connecting a low impedance load to a power source draws...
An impedance analyzer is a type of electronic test equipment used to measure complex electrical impedance as a function of test frequency. Impedance is...
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