Gary A. Zets

Vibrotactile transduction and transducers

The bodys sense of touch is potentially a versatile channel for the conveyance of directional, spatial, command, and timing information. Most practical implementations of vibrotactile systems require compact, light-weight actuators that can be mounted against the body. Eccentric mass motors are widely used for this application, yet their output is limited and the effects of loading on the transducers due to the skin and mounting arrangement have been largely ignored. Conventional linear actuators are well suited as vibrotactile transducers and can provide high output, but are typically limited to laboratory research due to their large size and cost. The effect of loading on various practical vibrotactile transducers is investigated using a skin impedance phantom and measuring the transducer displacement with respect to additional mass loading. Depending on the transducer design, loading can dramatically reduce the vibratory displacement and, in the case of eccentric mass motors, also increase the operating frequency. In contrast, a new linear actuator design can be designed to be almost independent of skin loading, by considering the mechanical impedance of the load and optimizing the transducer contact area.

Development of dual tactor capability for a soldier multisensory navigation and communication system

Development of new multisensory Soldier display systems requires context-driven evaluation of technology by expert users to assure generalizability to operations. The capture of Soldier performance demands is particularly challenging in this regard, as many factors converge to impact performance in actual usage. In this paper, we describe new capabilities for tactile communications that include an authoring system, use of android-driven displays for control and map-based information, and engineering tactors with differing salient characteristics. This allows development of a dual-tactor display that affords a larger variety of tactile patterns for communications, or TActions. These innovations are integrated in a prototype system. We used the system to present navigational signals to combat-experienced soldiers to guide development of tactile principles and the system itself. Feedback was positive for the concept, operational relevance, and for ease of interpretation.

Development of a planar shear sensor

This paper describes a wearable sensor that simultaneously measures both shear and orthogonal force. The planar shear sensor is based on inductive coupling between a small target and a series of adjacent coils. Lateral movement of the target changes the coupling between a primary coil and a series of geometrically shaped and scaled sense coils. Design of the sensor and methods for calibration are investigated. The wearable sensor can be used for measurement of in-situ foot loading during ambulation and we postulate that this may be useful for biomechanical analysis including exoskeletons and balance rehabilitation applications.

Multimodal Feedback for Balance Rehabilitation

This paper describes development of an activity based, multimodal balance rehabilitation training device. Various sensors can be used, including a force plate, inertial sensors, and depth sensing cameras, and various combinations of visual, auditory and tactile feedback can be configured depending on the rehabilitation task and activity. Tactile feedback is presented via a lightweight belt that is worn on the torso. Generally, visual feedback is only needed at the start of rehabilitation training (task orientation) while tactile feedback may be used to augment balance control. Tactile feedback can be configured as a cue that certain movement targets or limits have been reached or as an immediate indicator of the variance in postural sway. Tactile feedback allows the subject to naturally concentrate on the functional rehabilitation task, and is less reliant on visual or verbal cues.

Vibrotactile pattern perception as a method for the assessment of brain dysfunction

An immediate need exists for a portable diagnostic device for the assessment of cortical function, and diagnosis of mTBI. This paper presents initial results using a vibrotactile acuity test for the objective and quantitative diagnosis of acute mTBI suspects. mTBI is hypothesized to involve derangement or damage to the underlying cortical network. In particular, fundamental building blocks of the cortex are changed in such a way as to limit the functional connectivity within and between cortical columns. Our approach is based on sensory illusions that are configured as a test of neural connectivity. Pilot clinical test data showed differences between a small healthy normal group and a concussion group using a sports concussion model.