Vrije Universiteit Brussel

Variable Impedance Actuators

The R&MM research group has many years of experience with the development, design and control of Variable Impedance Actuators or VIAs. The following compliant actuators are developed in-house:

PPAM: Pleated pneumatic artificial muscles

Pleated Pneumatic Artificial Muscles , or in short PPAMs, were developed at our department in an effort to design an actuator for a bipedal walking robot that dealt with the drawbacks of existing muscle models. This led to a superior design having a maximal contraction range, no stick-slip or friction and an enormous force output.

MACCEPA actuator

The MACCEPA (The Mechanically Adjustable Compliance and Controllable Equilibrium Position Actuator) is a straightforward and easy to construct rotational electrical actuator, of which the compliance can be controlled separately from the equilibrium position. Each of these parameters is set by a position controlled servo motor. Moreover, the torque is a linear function of the compliance and of the angle between equilibrium position and actual position.

The MACCEPA 2.0 is the follow-up version where the torque-angle curve and consequently the stiffness-angle curve can be modified by choosing an appropriate shape of a profile disk, which replaces the lever arm of the original design.

SPEA: Series-Parallel Elastic Actuator

It is only recently that our research group started the research on a novel compliant actuation concept: Series-Parallel Elastic Actuation . This actuator enables to lower the required motor torque as a function of the number of parallel springs in the actuator and to increase the energy efficiency.


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