How an Exoskeleton Joint Moves with a Motor, Screw, and Linkage

This patent describes a compact and efficient way to make an exoskeleton joint bend and straighten using a motor, a special screw, and a clever set of levers.

What it covers

This patent details an actuator mechanism for an exoskeleton joint. It connects a first support (like a thigh brace) and a second support (like a shin brace) to a wearer. The actuator uses a motor (claim 1) that spins a 'ball screw' (claim 1). This screw then moves a 'ball nut' along its length, which in turn pushes or pulls a 'yoke' (claim 1). The yoke is designed to move only in a straight line, acting like a slider (claim 1). This straight-line motion of the yoke then pushes or pulls a 'linkage,' which is a rod or bar (claim 1). Finally, the linkage causes a 'joint crank' to rotate around the exoskeleton's main joint (claim 1), making the two supports move relative to each other, like bending a knee. For example, as the motor spins, the yoke slides, pushing the linkage, which rotates the joint crank to bend the exoskeleton's knee joint.

What it doesn't cover

• —Does not cover exoskeleton joints that use direct rotary motors without a ball screw and linkage system.
• —Does not cover actuators where the yoke rotates or moves in a non-linear fashion, as it specifies the yoke moves 'only in translation' (claim 1).
• —Does not cover systems where the motor, ball screw, ball nut, and yoke are not arranged collinearly (claim 1).
• —Does not cover actuators that rely on hydraulic or pneumatic cylinders instead of a motor and ball screw mechanism.
• —Does not cover a roller and joint cam system, as described in the abstract, if it does not also include the linkage and joint crank as claimed (claim 1).

The clever bit

The novelty lies in the specific combination and arrangement of components: using a ball screw to translate a yoke, which then acts as a slider to drive a linkage and joint crank. This efficiently converts linear motion into powerful rotational motion at the joint, while constraining the yoke to pure translation for reliability.

Why it matters

Exoskeletons need powerful yet precise ways to move their joints to help people walk or lift heavy objects. This patent focuses on a specific mechanical design for these actuators, aiming for efficiency and control. The design elements, such as the ball screw and linkage, are critical for translating a motor's rotation into the strong, controlled bending and straightening motions required for human assistance or augmentation.

Real-world examples

• 1.Ekso Bionics EksoNR exoskeleton
• 2.Powered prosthetic limbs
• 3.Industrial assist exoskeletons
• 4.Robotic rehabilitation devices