Design and development of a wearable sensory system for measuring the knee flexion-extension angle

Finished: 2019-09-27

Other assignment

Nowadays there are several sensors and techniques for tracking body segments motion and estimating joint kinematics. According to the literature, motion capture systems can be divided in two main groups:

  1. Optical Systems
  2.  Non-Optical Systems

Optical Systems (e.g: stereo-photogrammetric systems, optoelectronics systems, etc) are considered the “Gold Standard” for the human movement analysis. Such systems can provide accurate evaluation of human motion but they can be only used in a structured environment.
On the other hand, Non-Optical systems (e.g: potentiometers, encoders, M-IMU, magnetic sensors, e-textiles, optical fibers, etc) are characterized by less accuracy than Optical Systems but they can be used in free-living environments.

The goal of this project is to design and develop a wearable sensory system for monitoring the knee flexion-extension angle. 

According to the State of the art only Non-Optical systems are wearable, therefore we have focused on this transducer class.

The sensory system has to be integrated in a soft robotic knee brace, composed by two pneumatic artificial muscles, which is used in the knee rehabilitation process after anterior cruciate ligament (ACL) injuries.  ACL is one of the two ligament that crosses the knee joint. It connects femur and tibia and It helps to stabilize the knee, avoiding the anterior translation between thighbone and shinbone.

The sensory system selected consists on two precision potentiometers (one per side) which are integrated in the knee brace through an appropriate mechanism which, linking the rotation of the knee joint to the rotation of the potentiometer shaft, gives us the possibility to measure the knee flexion-extension angle during different rehabilitation process.