Adjustable Stiffness "Jack" Spring Actuator Concept

Thomas Sugar (Inventor)

Research output: Patent


Over the past two decades increased interest has been devoted to developing 'compliant' robotic systems, which incorporate a degree of 'give' or 'softness' into the typical rigid, linked system. In early applications, compliant systems allowed robots to perform force-sensitive tasks such as surface grinding. More recently, interest has grown in developing wearable robots & exoskeletons to enhance strength or restore lost functionality. In developing such systems, designers must face the issues of weight, power consumption, and operator safety.To meet the challenges inherent in these constraints, actuators based upon spring concepts offer a promising solution. Researchers at Arizona State University have developed a 'jack' spring actuator concept which is inherently compliant, energy-conservative, and lightweight. Unlike current actuators, the jack spring actuator can be controlled via multiple methods - end effector position control, end effector 'equilibrium' position control, and end effector force control. Thus, the jack spring actuator can control the structural stiffness (static stiffness), the adjustable stiffness (dynamic stiffness), and actuator position. The jack spring offers lower weight than a traditional lead screw actuator, uses a spring to replace the traditional heavy gearbox, and has the ability to store energy in the spring to drive a load. It can be used in prostheses for rehabilitation or performance enhancement, for motion control and damping, and in a wide variety of other actuation applications.
Original languageEnglish (US)
StatePublished - Aug 19 2004


Dive into the research topics of 'Adjustable Stiffness "Jack" Spring Actuator Concept'. Together they form a unique fingerprint.

Cite this