A Vibro-Haptic Human-Machine Interface for Structural Health Monitoring

Abstract

The goal of the structural health monitoring (SHM) community has been to endow physical systems with a nervous system not unlike those commonly found in living organisms. Typically the SHM community has attempted to do this by instrumenting structures with a variety of sensors, and then applying various signal processing and classification procedures to the data in order to detect the presence of damage, the location of damage, the severity of damage, and to estimate the remaining useful life of the structure. This procedure has had some success, but we are still a long ways from achieving the performance of the nervous systems found in biology. Primarily because contemporary classification algorithms do not have the performance required. In many cases expert judgment is superior to automated classification. This work introduces a new paradigm. Instead of trying to build a nervous system from scratch, we propose interfacing the human nervous system to the distributed sensor network located on the structure and developing new techniques to enable human-machine cooperation. Results from the field of sensor substitution suggest this should be possible. Sensor substitution is a process by which a human can partially regain the use of a lost sense using a different sense as a surrogate. The plasticity of the human brain allows the human to interpret the stimuli to the alternative sense as coming from the original sense that was lost. Recent advances in smart structures haptic technology have enabled a wide range of new human-machine interfaces to facilitate sensory substitution. Examples of these interfaces include force feedback for robotic applications, refreshable Braille displays, and prosthesis devices. Thus far, haptic devices have mainly been limited to physical applications. It is possible that haptic devices may allow humans a new interface to interact with abstract entities such as the data from a wireless sensor network, the topography of a high dimensional cost function, or the structural health of a wind farm. This study investigates vibro-haptic human-machine interfaces for SHM. The investigation was performed using a surrogate three-story structure. The structure features three nonlinearity-inducing bumpers to simulate damage. Accelerometers are placed on each floor to measure the response of the structure to a harmonic base excitation. The accelerometer measurements are preprocessed using Principal Component Analysis (PCA) via