Energy-Efficient, Real-Time Variable Stiffness Ankle-Foot Prosthesis

Technology #34461

Key points

  • Quickly adjusts ankle stiffness to support changes in walking conditions like inclines and declines
  • Provides highly efficient energy return with a small amount of ankle dorsiflexion
  • Saddle spring design incorporates rigid and compliant materials


Researchers at the University of Central Florida have developed an innovative, bio-inspired ankle-foot prosthesis that can automatically adjust its ankle stiffness to accommodate different activities. For example, the device can quickly adapt to walking conditions such as inclines, declines, and uneven soft or hard surfaces. The novel prosthesis uses a highly efficient energy recycling device that mimics the saddle spring mechanism found in a stomatopod known as the mantis shrimp.

Current passive prostheses for individuals with below-knee amputations typically provide a single stiffness setting that can lead to improper walking behaviors such as asymmetry, increased musculature demands, and excessive joint load. Though other prostheses address some of the ankle stiffness and walking issues, the devices are slow to respond and are rigid, bulky and heavy.

Technical Details

The UCF technology is a lightweight prosthesis that provides efficient high-energy return using a mechanism with a unique core comprising different rigid and compliant layers. The design enables the device to support continuous changes in curvature as the orientation of the user varies. A direct-current brushless motor in the prosthesis enables the mechanism to rotate and quickly change stiffness to suit different walking conditions. In one embodiment, a rigid foot blade material allows the prosthesis to store energy during the stance phase.

Partnering Opportunity

The research team is looking for partners to develop the technology further for commercialization.

Related Technologies

34171—Novel Ankle Prosthetic Module Maximizes the Propulsion Efficiency of Passive Prostheses


  • Lightweight
  • Adjusts stiffness faster and provides higher energy return efficiency compared to existing technologies

Market Application

Prosthetics and orthotics