The Exoskeleton Terminology Glossary: Essential Definitions
Introduction to Wearable Robotics Terminology
As the field of wearable robotics transitions from academic research into widespread industrial and commercial application, the need for a standardized, clear terminology becomes increasingly critical. This glossary serves as a foundational reference for engineers, medical professionals, and operators, defining the core mechanical, electrical, and biological terms used to describe exoskeleton systems.
The terminology of exoskeletons draws from diverse disciplines, including mechanical kinematics, human biomechanics, materials science, and control theory. Understanding these terms is essential for evaluating device performance, safety standards, and structural architectures.
Whether you are analyzing a passive joint assist or an active, multi-degree-of-freedom robotic system, this glossary provides the precise definitions required to navigate the technical literature and program specifications of modern wearable systems.
Mechanical and Kinematic Glossary Terms
Kinematics: The study of motion without regard to the forces that cause it. In exoskeleton engineering, kinematics refers to the geometric alignment and movement mapping of the machine's joints in relation to human joints.
Degrees of Freedom (DoF): The number of independent directions in which a joint or structure can move. For example, a simple hinge joint has 1 DoF, while the human shoulder joint possesses 3 DoF (flexion/extension, abduction/adduction, internal/external rotation).
Parallel Load Path: A physical routing configuration where external forces and compressive loads are diverted around a biological structure (such as the spine) and channeled through a parallel mechanical frame directly to a support point.
Actuation and Sensor Glossary Terms
Actuator: A mechanical device responsible for moving or controlling a mechanism. In active exoskeletons, actuators (such as BLDC motors or hydraulic pistons) convert energy into supportive joint torques.
Surface Electromyography (sEMG): A non-invasive sensing technique that measures the electrical activity of muscles through electrodes placed on the skin, used to predict a user's movement intention.
Backdrivability: The ease with which an actuator can be physically moved by an external force when powered off. High backdrivability is crucial for user comfort and safety, allowing natural movement when active assistance is inactive.
Biomechanical and Structural Glossary Terms
Metabolic Cost: The amount of biological energy (oxygen consumption and heart rate) expended by the body to perform a specific physical activity. A successful mobility exoskeleton reduces this cost.
Anatomical Anchor: A secure contact point where an exoskeleton or soft suit attaches to the wearer's skeleton (such as the waist or ankle), serving as the foundation for load transfer.
Exoshape: A term designating the external, load-bearing geometry of an adaptive wearable structure, particularly one that dynamically alters its physical configuration or stiffness in response to biomechanical demand.