Bio inspired artificial muscle actuation
Status
The Link Stacking Actuator (LSA) is not currently a commercial product. The underlying system and methods are protected under U.S. Patent 10,967,524, titled “System and method for conversion of rotational motion into linear actuation by mechanical stacking or unstacking of connected links.” The patent and implementation concepts are available for discussion in the context of collaboration, licensing, or acquisition.
Overview
A Link Stacking Actuator is a scalable device that converts rotational input into linear contraction by mechanically stacking interconnected links. Under torsion, the links fold and stack into a dense structure that shortens along its length and generates linear force. When the torsion is relaxed, the stack unbuilds and the actuator extends again.
Conceptually, LSA behaves as an artificial muscle. It accepts rotary drive from a motor and produces controlled linear contraction in a compact, mechanically efficient form. Because the active element is a linked chain rather than a rigid cylinder, an LSA can be routed around corners, edges, and structural features, then stacked to generate force along that routed path. By rethinking how motion is generated and transmitted, the design aims to provide muscle like behavior without the complexity and bulk of traditional rotary to linear mechanisms.
How it works
In an LSA, a chain of linked elements is coupled to a motor that applies rotational torque.
The links are arranged so that, when torsion is applied along the chain, they twist and fold into a stacked geometry.
As stacking progresses, the effective length of the actuator decreases and a linear contractile force is generated between its mounting points.
The direction of rotation controls whether the actuator contracts into a stack or relaxes back into an extended chain.
The device generates significant linear force during contraction, while expansion is essentially a controlled relaxation of the stacked structure. Before stacking, the link chain can bend and conform to surrounding geometry, so the actuator path can curve around structure while still delivering net contractile force between its mounting points.
When driven from one end against a fixed mount, a single LSA can pull a load. When two LSAs are used in opposition around a joint, they can actuate hinged beams such as robotic arms, legs, or fingers. Configured in parallel sets, they can be used for direct lift and other high force applications.
Design characteristics
Scalable geometry
Actuator length and cross section can be tuned by changing the number, size, and shape of the links and the configuration of the stack, which allows designs from small tendon like units to larger lift elements.
Rotational to linear conversion
LSA directly converts rotary motor output into linear contraction, without the need for lead screws, rack and pinion, or bulky linkage assemblies.
Muscle like behavior
The actuator produces high force when motion is small and relaxes when motion increases, which fits well with hinged member designs where torque requirements vary through the range of motion.
Force routing around structure
Because the active element is a flexible chain of links before stacking, an LSA can be routed around corners, edges, and internal frames, then stacked to pull along the overall path. This allows actuators to work around obstacles and inside tight volumes where straight line cylinders or screw based actuators cannot fit.
Compact and mechanically elegant
When stacked, the structure is dense and can be packaged in forms that do not resemble traditional cylinders or screw based actuators, which is useful for anthropomorphic or space constrained designs.
Potential applications
LSA was conceived for use anywhere muscle like actuation is valuable.
Robotics, including arms, legs, grippers, and articulated mechanisms
Prosthetics and exoskeletons, where compact high force actuation is required
Industrial or aerospace mechanisms that benefit from cable free rotary to linear conversion
Research platforms in bio inspired actuation and alternative motion systems
The design is especially relevant where traditional motor and screw or cylinder systems are too bulky, inefficient, or mechanically constrained for the desired form factor.
Licensing and technology transfer
The Link Stacking Actuator patent covers the core system and method for generating linear contraction from rotational input by stacking and unstacking linked elements. The concept is suitable for implementation at a range of scales, with different link geometries, materials, and packaging strategies.
Morgan Dynamic Research is open to serious inquiries related to licensing, co development, or acquisition of the LSA patent and associated design work. For discussion of technical details or potential applications, contact us.