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Mechanical Systems01:22

Mechanical Systems

Mechanical systems are analogous to to electrical networks where springs and masses play similar roles to inductors and capacitors, respectively. A viscous damper in mechanical systems functions similarly to a resistor in electrical networks, dissipating energy. The forces acting on a mass in such systems include an applied force in the direction of motion, counteracted by forces from the spring, a viscous damper, and the mass's acceleration. This interplay of forces is mathematically described...
ATP Driven Pumps III: V-type Pumps01:30

ATP Driven Pumps III: V-type Pumps

V-type pumps are ATP-driven pumps found in the vacuolar membranes of plants, yeast, endosomal and lysosomal membranes of animal cells, plasma membranes of a few specialized eukaryotic cells, and some prokaryotes. They are also known as the V1Vo-ATPase, that couple ATP hydrolysis to transport protons against a concentration gradient.
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
Electro-mechanical Systems01:19

Electro-mechanical Systems

Electromechanical systems are intricate configurations that effectively combine electrical and mechanical elements to achieve a desired outcome. Central to many of these systems is the DC motor, a device that converts electrical energy into mechanical motion, enabling various applications ranging from simple fans to complex robotic mechanisms.
A key component of the DC motor is the armature, a rotating circuit positioned within a magnetic field. As an electric current passes through the...
Mechanical Efficiency of Real Machines01:14

Mechanical Efficiency of Real Machines

The mechanical efficiency of a machine is a fundamental concept that describes how effectively a machine can convert input work into output work. According to this concept, the efficiency of a machine is equal to the ratio of the output work to the input work. An ideal machine, meaning a machine that has no energy losses, has an efficiency of one. This implies that the input work and the output work are equal.
However, in reality, no machine can be truly ideal, and all of them experience some...
PD Controller: Design01:26

PD Controller: Design

In automotive engineering, car suspension systems often employ Proportional Derivative (PD) controllers to enhance performance. PD controllers are utilized to adjust the damping force in response to road conditions. A controller, acting as an amplifier with a constant gain, demonstrates proportional control, with output directly mirroring input.
Designing a continuous-data controller requires selecting and linking components like adders and integrators, which are fundamental in Proportional,...
Application of Pascal's Law01:03

Application of Pascal's Law

Pascal's experimentally proven observations—that a change in pressure applied to an enclosed fluid is transmitted undiminished throughout the fluid and to the walls of its container—provide the foundations for hydraulics, one of the most important developments in modern mechanical technology.
Hydraulic systems are used to operate automotive brakes, hydraulic jacks, and numerous other mechanical systems. We can derive a relationship between the forces in a simple hydraulic system by applying...

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Related Experiment Video

Updated: May 13, 2026

Fabrication of Soft Pneumatic Network Actuators with Oblique Chambers
07:09

Fabrication of Soft Pneumatic Network Actuators with Oblique Chambers

Published on: August 17, 2018

Variable gearing in a biologically inspired pneumatic actuator array.

Emanuel Azizi1, Thomas J Roberts

  • 1Department of Ecology and Evolutionary Biology, University of California , Irvine, CA 92697, USA. eazizi@uci.edu

Bioinspiration & Biomimetics
|March 7, 2013
PubMed
Summary
This summary is machine-generated.

Pennate muscles use changing fiber angles to adjust their speed and force, acting like a variable gear system. Researchers replicated this in artificial muscles, showing bio-inspired designs can automatically adapt to different loads.

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Area of Science:

  • Biomechanics
  • Robotics
  • Materials Science

Background:

  • Pennate muscles feature fibers angled to the line of action, which rotate during contraction, altering the pennation angle.
  • This dynamic change in pennation angle amplifies fiber shortening velocity and muscle output velocity, creating a variable gear ratio.
  • Previous research indicates pennate muscles automatically adjust their gear ratio based on load, operating at high gear for rapid contractions and low gear for forceful ones.

Purpose of the Study:

  • To investigate if a pennate array of artificial muscles can replicate the variable gearing behavior observed in biological pennate muscles.
  • To understand the role of fiber rotation and muscle bulging in the variable gearing mechanism.

Main Methods:

  • Utilized McKibben-type pneumatic actuators arranged in a pennate array to mimic biological muscle structure.
  • Quantified the system's gear ratio by measuring actuator rotation and contraction against a range of loads using video analysis.

Main Results:

  • The artificial pennate muscle array demonstrated a variable gear ratio that decreased significantly with increasing load, mirroring biological muscle behavior.
  • Variable gearing was attributed to load-dependent variations in actuator rotation, analogous to fiber rotation in biological muscles.
  • The radial expansion of actuators during shortening was identified as a key factor in the variable gearing mechanism.

Conclusions:

  • Variable gearing in pennate muscles is mediated by fiber rotation and the direction of muscle bulging.
  • Bio-inspired artificial muscle architectures offer potential for automatic force and speed adaptation under varying load conditions.
  • This study supports the principle of variable gearing in pennate muscles and its potential replication in artificial systems.