Dynamics and Control of the Robotic Lumbar Spine (RLS)

This paper presents the dynamics and nonlinear control of the Robotic Lumbar Spine (RLS). The RLS is a 15 degree-of-freedom, fully cable-actuated robotic lumbar spine which can mimic in vivo human lumbar spine movements to provide better hands-on training for medical students. The current design includes five active lumbar vertebrae and the sacrum, with dimensions of an average adult human spine. It is actuated by 20 cables connected to electric motors. Every vertebra is connected to the neighboring vertebrae by spherical joints. Medical schools can benefit from a tool, system, or method that will help instructors train students and assess their tactile proficiency throughout their education. The robotic lumbar spine has the potential to satisfy these needs in palpatory diagnosis. Additionally, a new approach to solve for positive and nonzero cable tensions that are also continuous in time is introduced.