Lindie Burgess earns MS in Mechanical Engineering

Congratulation to Lindie for successfully presenting her work on the design and implementation of a test jig for our novel knee design.

Abstract:
Much can be learned about material properties, kinematics, dynamics, and control of biological systems through the design of robots which mimic biology. Additionally, biologically inspired robots can offer platforms on which to test controllers and to study assistive technology. Steady progress has been made in Portland State University’s Agile and Adaptive Robotics Lab in developing a Biomimetic Humanoid Bipedal Robot. Artificial skeletal features are 3D printed in Onyx and artificial muscles are implemented using Festo brand pneumatic actuators. A knee joint, whose center of rotation translates as the tibia rotates about the knee, was previously developed to have similar range of motion as a human. Accompanying the physical design, algorithms were written to determine origin and insertion points for the Pneumatic Artificial Muscles (PAMs) so that the resulting torque profiles about the knee joint closely matches the torque profiles of these same muscles in a human.

The primary goal of this project was to design and fabricate a test jig which facilitates the acquisition of the true torque profile resulting from the actuation of the PAMs about the knee of the robot. Data collected on this jig will be used to validate and refine the models used to design PAM attachment locations.

The femur is statically connected to the test jig while the tibia can rotate, in controlled intervals, about the knee. At the limit of each interval, a load cell quantifies the force induced by isometric contraction of the PAM and an image is taken to gather angle measurements through post processing.