Active impedance control in a water‐filled waveguide for low‐frequency bioacoustic testing

1997 ◽  
Vol 102 (5) ◽  
pp. 3196-3197
Author(s):  
James J. Finneran ◽  
Mardi C. Hastings
Keyword(s):  
Impedance Control ◽  
Low Frequency ◽  
Active Impedance

scholarly journals Towards versatile legged robots through active impedance control

2015 ◽  
Vol 34 (7) ◽  
pp. 1003-1020 ◽  
Author(s):  
Claudio Semini ◽  
Victor Barasuol ◽  
Thiago Boaventura ◽  
Marco Frigerio ◽  
Michele Focchi ◽  
...  
Keyword(s):  
Impedance Control ◽  
Legged Robots ◽  
Active Impedance

scholarly journals High-Bandwidth Active Impedance Control of the Proprioceptive Actuator Design in Dynamic Compliant Robotics

Actuators ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 71 ◽  
Author(s):  
Simon Hjorth Jessing Lund ◽  
Peter Billeschou ◽  
Leon Bonde Larsen
Keyword(s):  
Pulse Width Modulation ◽  
Compliant Mechanisms ◽  
Controller Design ◽  
Impedance Control ◽  
Experimental Tests ◽  
Angle Sensor ◽  
High Performing ◽  
High Bandwidth ◽  
Torque Observer ◽  
Active Impedance

Dynamic compliant robotics is a fast growing field because of its ability to widen the scope of robotics. The reason for this is that compliant mechanisms may ensure safe/compliant interactions between a robot and an external element—for instance, a human operator. Active impedance control may widen the scope even further in relation to passive elements, but it requires high-bandwidth robust torque and active impedance control which induces high-noise issues even if high-end sensors are used. To address these issues, a complete controller design scheme, including Field-Oriented Control (FOC) of a Brushless Direct Current (BLDC) motor, is proposed. In this paper, controller designs for controlling the virtual impedance, motor torque and field are proposed which enables high-bandwidth robust control. Additionally, a novel speed and angle observer is proposed that aims to reduce noise arising in the angle sensor (typically a 12-bit magnetic encoder) and a Kalman/Luenberger based torque observer is proposed that aims to reduce noise arising in the phase current sensors. Through experimental tests, the combination of the controller designs and observers facilitated a closed-loop torque bandwidth of 2 . 6 k Hz and a noise reduction of 13 . 5 (in relation to no observers), at a sample rate and Pulse Width Modulation (PWM) frequency of 25 k Hz . Additionally, experiments verified a precise and high performing controller scheme both during impacts and at a variety of different virtual compliance characteristics.

Impedance Control of Gyroscopic Power Generator

2011 ◽  
Author(s):  
Tomoyuki Takahashi ◽  
Jun Iwasaki ◽  
Hiroshi Hosaka
Keyword(s):  
Steady State ◽  
Phase Difference ◽  
High Speed ◽  
Control Method ◽  
Impedance Control ◽  
Low Frequency ◽  
Power Generator ◽  
Communication Devices ◽  
High Speed Rotation ◽  
The Stability

The gyroscopic power generator produces a high-speed rotation of magnets from low-frequency vibrations and supplies electric power to information and communication devices that use human vibrations in daily life. In this paper, in order to increase the stability and the output power of the generator, a simple equation that indicates the steady state approximate solution of the phase difference is derived. From the derived solution, a control method for the steady state is verified by the simulations. In order to maintain the stability and high power generation for variable input vibrations, the impedance control method using the phase difference is developed and verified experimentally.

Design of an Active-Vibration System Based on Sky-Hook Damper and Impedance Control

2013 ◽  
Vol 416-417 ◽  
pp. 860-865
Author(s):  
Wu Sung Yao ◽  
Po Wen Hsueh ◽  
Mi Ching Tsai
Keyword(s):  
Impedance Control ◽  
Low Frequency ◽  
Control Design ◽  
Experimental Results ◽  
Vibration System ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Low Frequency Vibration ◽  
Model Reference Control ◽  
Active Vibration

This paper investigates an active anti-vibration system, and the isolation of low-frequency vibration is studied. A model reference control of the anti-vibration system with a sky-hook damper and impedance control is analyzed. An illustrated example of a single-degree-of-freedom anti-vibration system driven by a tubular linear servomotor is given to verify the performance of the proposed control design. Experimental results are given to show that the peak resonance value of 0dB within a frequency of 10Hz can be achieved successively.

scholarly journals Dual-Frequency RF Impedance Matching Circuits for Semiconductor Plasma Etch Equipment

Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2074
Author(s):  
Jeongsu Lee ◽  
Sangjeen Hong
Keyword(s):  
Impedance Control ◽  
Impedance Matching ◽  
Low Frequency ◽  
Electrode Impedance ◽  
Dual Frequency ◽  
Plasma Etch ◽  
Bias Power ◽  
Ion Energy ◽  
Specific Frequency ◽  
Frequency Power

The change in electrode impedance of semiconductor equipment due to repetitive processes is a major issue that creates process drift. In the current plasma etch chamber with a dual-frequency power system, the high-powered radio frequency (RF) source contributes to the enhancement of the plasma density, and the low-frequency bias power at the bottom electrode is adopted to enhance the injected ion energy in the plasma. The impedance control of the top electrode in dual-frequency capacity coupled plasma limits the impedance matching capability of the RF matching system because it only considers the high-frequency RF source. To control the precise impedance in dual-frequency semiconductor equipment, independent impedance control is required for each frequency. In this study, the impedance corresponding to a specific frequency was independently controlled using L (inductor) and C (capacitor). A 60 MHz stop filter and VVC were used to control 2 MHz impedance at a specific point, and a 2 MHz stop filter and VVC were used to control 60 MHz impedance. In the case of 2 MHz impedance control, the 2 MHz impedance changed from 10.9−j893 to 0.3−j62 and the 60 MHz impedance did not change. When controlling the 60 MHz impedance, the 60 MHz impedance changed from 0.33 + j26.53 to 0.2 + j190 and the 2 MHz impedance did not change. The designed LC circuits cover the impedance of 60 and 2 MHz separately and are verified by the change in the capacitance of the vacuum variable capacitors implemented in the RF impedance matching system.

Impedance control of a cable-driven SEA with mixed H2/H∞ synthesis

2017 ◽  
Vol 37 (3) ◽  
pp. 296-303 ◽  
Author(s):  
Ningbo Yu ◽  
Wulin Zou
Keyword(s):  
Control Strategy ◽  
Control Method ◽  
Impedance Control ◽  
Low Frequency ◽  
Human Robot Interaction ◽  
Control Input ◽  
Robot Interaction ◽  
Content Type ◽  
Series Elastic Actuator ◽  
Series Elastic

Purpose This paper aims to present an impedance control method with mixed H2/H∞ synthesis and relaxed passivity for a cable-driven series elastic actuator to be applied for physical human–robot interaction. Design/methodology/approach To shape the system’s impedance to match a desired dynamic model, the impedance control problem was reformulated into an impedance matching structure. The desired competing performance requirements as well as constraints from the physical system can be characterized with weighting functions for respective signals. Considering the frequency properties of human movements, the passivity constraint for stable human–robot interaction, which is required on the entire frequency spectrum and may bring conservative solutions, has been relaxed in such a way that it only restrains the low frequency band. Thus, impedance control became a mixed H2/H∞ synthesis problem, and a dynamic output feedback controller can be obtained. Findings The proposed impedance control strategy has been tested for various desired impedance with both simulation and experiments on the cable-driven series elastic actuator platform. The actual interaction torque tracked well the desired torque within the desired norm bounds, and the control input was regulated below the motor velocity limit. The closed loop system can guarantee relaxed passivity at low frequency. Both simulation and experimental results have validated the feasibility and efficacy of the proposed method. Originality/value This impedance control strategy with mixed H2/H∞ synthesis and relaxed passivity provides a novel, effective and less conservative method for physical human–robot interaction control.

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