BACKGROUND:  In linear motors, clamping mechanisms are employed to induce movement and transfer force. A common clamping design found in these devices involves interlocking teeth which can support large lateral forces, but have a step size limited by the pitch, or the distance between two teeth. Although, the use of microelectromechanical system (MEMS) technology has drastically reduced the step size, or pitch, the spacing is still finite and potentially limited for high precision applications. The optimal design for this type of clamping mechanism would provide infinite pitch resolution, yet yield a strong holding force and allow fast operation.

INNOVATION:  This invention effectively provides infinite pitch precision for motor systems, gearing systems, and applications requiring high spatial resolution placement. The invention is comprised of an indenter, which has teeth, and a pseudoelastic material, which is flat. When the surfaces are pressed together during the clamping process, the pseudoelastic material conforms to the shape of the indenter allowing significant loads to be transferred. When the indenter is removed, the pseudoelastic material quickly recovers its original shape. Indenters of any pitch may be engaged into the pseudoelastic material, and even multiple indenters with various pitches may be linked simultaneously. Because this mechanism does not require interactions between two sets of teeth, the pitch is effectively reduced to zero which yields infinite precision in the mechanism.

POTENTIAL APPLICATIONS 

• Linear motors (stepper, DC brushed and brushless servo, inductance and AC synchronous, etc.)
• Gearing and clamping systems
• Precision placement applications (medical/surgical, dental, optical, etc.)

ADVANTAGES

• Fast-acting (up to 10 kHz cycling), high holding-force, infinite step-size, low-wear gear with no backlash
• Ability to link multiple gears
• Increased operational frequency over similar designs employing shape-memory alloys

DEVELOPMENT-TO-DATE:  Reduced to practice a laboratory prototype

Related Papers (Selected)

• Mesoscale actuator device: micro interlocking mechanism to transfer macro load. Q. Chen, D.J. Yao, C.J. Kim, and G.P. Carman, Sensors and Actuators A: Physical, vol. 73, is. 1-2, pg. 30-36 (1999) [more]
• High friction interface with pseudoelastic NiTi. S. Chatterjee and G. P. Carman, Appl. Phys. Lett. 91, 024104 (2007) [more]

Reference: UCLA Case No. 2002-360

PCT Application: US2004/004161