Wearable Tactile Pressure Sensing for Compression Garments and Control of Active Compression Devices

Abstract

Compression garments on the lower limbs have been used for the treatment of venous deficiencies for centuries. More recently, healthy athletes have used similar garments for an edge in performance and improved recovery times. The basis for their use is the increase of blood circulation that helps oxygenate muscles. Active compression devices that apply intermittent compression are less prevalent but have the potential to generate a greater impact on blood circulation. A new study into the effects of active compression required the development of an active compression system that would apply intermittent compression in a reliable manner. In the present thesis, a control system to facilitate active compression and generate a positive impact on blood circulation is pursued. This development involved setting up the timing of the compression and implementing a controller that regulates the compression pressure. A new capacitive sensor for pressure feedback to the controller is also evaluated. In the resulting active compression system that was built, an electrocardiogram (ECG) and heel switch are used to determine the timing of the compression. The ECG synchronizes the compression with the heartbeat, while the heel switch prevents compression from being applied when the calf muscles are contracted because the compression would not have an effect in that scenario. When the timing criteria is met, sequential compression up the calf is applied with five inflatable cuffs to push the blood up the leg and towards the heart. The pressure is sensed during each compression and used in an iterative learning controller that regulates the amount of compression applied.