Helmet-Mounted Display Tracking With Adaptive Vibration Prediction
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Solution Overview
Problem
Existing helmet-mounted display systems experience instability in symbol display due to involuntary head movements caused by vibrations, leading to unacceptable latency and symbol lag during updates.
Innovation Solution
A system utilizing a vibration sensor, non-vibrational head tracker, and adaptive filter to estimate the body transfer function, predicting head orientation ahead of time to mitigate the effects of vibrations, combined with a recursive least squares (RLS) filter and finite impulse response (FIR) filter to correct and stabilize symbol positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If helmet-mounted display systems track head orientation to update symbol positions, then symbols appear fixed in space, but involuntary head movements from vibrations cause symbol instability and latency
Solution Approach 1:
The system predicts future head orientation based on current vibration patterns and motion trends, allowing the display to preemptively adjust symbol positions before actual head movement occurs. This prediction mechanism compensates for processing latency by preparing display updates in advance based on anticipated head position changes.
Solution Approach 2:
Vibration sensors serve as intermediaries that detect platform vibrations before they translate into head movements. By monitoring these intermediate vibration signals, the system can predict incoming head movements and pre-adjust symbol positions, reducing the perceived latency and improving display stability during vibratory events.
2Productivity
If the system updates symbol positions at high frequency to reduce latency, then display responsiveness improves, but symbol instability increases due to vibration-induced head movements
Solution Approach 1:
The system continuously monitors vibration sensor data and head tracker output, using this feedback to dynamically adjust symbol positioning. By incorporating real-time vibration information into the display update cycle, the system can compensate for vibration-induced head movements and maintain symbol stability even at high update frequencies.
Solution Approach 2:
The system changes the timing and magnitude of display updates based on detected vibration patterns. During high-vibration periods, the prediction algorithm adjusts update parameters to account for anticipated head movements, allowing high-frequency updates to remain stable by adapting to changing vibration conditions rather than using fixed update parameters.
Data Source
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AI summary
There is provided a method for determining an intended orientation and/or position of a user's head when the orientation of the user's head is being changed involuntarily by vibratory or buffeting forces transmitted through the user's body from a point of contact of the user's body with said forces. The method comprising: determining a force variable at the point of contact due to said forces; predicting, using an adaptive filter comprising a first input, a first output, a filter coefficient input, and at least one filter coefficient, an involuntary component of orientation of the user's head at a predetermined time due to the sensed variable, wherein the first output is equal to the involuntary component of orientation and the first input comprises the force variable; determining, using at least one tracking system, an orientation variable of the user's head at the predetermined time; subtracting a first value from a second value, the first value equal to the first output and the second value equal to the orientation variable, to provide a third value equal to the filter coefficient input; and updating the at least one filter coefficient based on the filter coefficient input.