Trunk Bending Apparatus

Trunk stiffness and stability can be related to the posture and alignment of the human body. This project continues on the evolution of the Twister, a trunk bending apparatus, that is intended to measure and acquire data of axial and torsional stiffness in core muscles. Then, postural performance can be linked to measured torso stiffness examine muscle reaction patterns with the consideration of age, height, weight, and other factors.

Background
In the 1980's, Dr. Victor Gurfinkel, medical researcher at Oregon Health & Science University, developed the Twister to measure torsional muscle tone as well as muscular responses as the apparatus twisted the subject. The body sections considered by the Twister are the neck, trunk, and waist to Then, Dr. Gurfinkel devoted the apparatus to Dr. Rajal Cohen at University of Idaho, Psychology & Communication Studies Department, upon his retirement.

The developers of the Twister seek to study the psychological mechanism caused by the change in length of muscles crossing the selected region as a result of the device twisting that region. The resulting resistive torque is determined to calibrate the tonic control of all muscles subjected to changes in length. Based on peek-to-peek magnitude, phase of resistive torque, and tonic electromyogram modulation, the results being acquired show magnitude and dynamic control of muscle activity. Moreover, Fay Horak, another developer of the Twister at Oregon Health & Science University, believes that the Twister will help answering how the brain control normal postural tone, and how abnormal tone can be improved with treatment [].

Problem Definition
The previous team assembled and modified the structure to be relevant for the trunk bending experiments. They created an interface software to collect data, upgraded the hardware, and built harnesses. The objective is to bring the machine. into an operational state by using higher quality parts, completing circuitry, making the machine more user-friendly, adding safety features, and testing and collecting data from the final product

Goals & Deliverables
To complete the project into an operational state, some universal joints are going to be replaced and new ones will be installed. A String potentiometer is going to be installed to measure the subject's bending when weights are applied. To make the final product more user-friendly, V-rollers are to be installed to allow easier movement of the attachment bars. Considering safety, an emergency stop is to be installed somewhere easy to be reached by the subject.