Velocity Prediction Using Interleaved Frame Rates
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Solution Overview
Problem
Current velocity prediction methods using two-dimensional optical navigation sensors, such as optical mouse devices, face challenges in accurately determining absolute velocity, especially when the initial condition is not at rest, and are prone to errors due to under-sampling and incorrect initial velocity assumptions.
Innovation Solution
Implementing a method that uses a 2D comb array with differential circuitry to generate differential signals at multiple frame rates, where the frame rates have a non-integer ratio, allowing for interleaved data collection and processing to compute velocity predictions along orthogonal axes, thereby correcting for initial condition errors and under-sampling by comparing and averaging velocity estimations from different frame rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If velocity prediction is performed using a single frame rate, then the device complexity is low, but the measurement precision of velocity is insufficient and prone to errors
Solution Approach 1:
The patent segments the velocity measurement process by using multiple frame rates (first frame rate and second frame rate) to obtain differential signals at different sampling intervals. This segmentation allows the system to compare velocity predictions from different frame rates and identify errors, thereby improving measurement precision without requiring a single complex high-precision sensor
Solution Approach 2:
The patent implements feedback by comparing the first velocity prediction (from first frame rate) with the second velocity prediction (from second frame rate). The system uses this comparison to detect discrepancies and correct velocity measurement errors, creating a self-correcting mechanism that improves accuracy while maintaining manageable system complexity
2Reliability
If the sensor operates at a single frame rate, then the energy consumption is low, but the reliability of velocity prediction deteriorates due to under-sampling errors
Solution Approach 1:
The patent employs periodic action by alternating between two different frame rates in an interleaved manner. The sensor array switches between operating at the first frame rate and the second frame rate, creating a periodic sampling pattern that captures motion information more reliably than a single frame rate, while the alternating nature helps manage energy consumption by not continuously operating at the higher frame rate
3Measurement precision
If velocity prediction assumes initial rest condition, then the device complexity is low, but the measurement precision deteriorates when the initial condition is not at rest
Solution Approach 1:
The patent applies preliminary action by performing velocity predictions at two different frame rates before finalizing the velocity measurement. This preliminary dual-rate sampling allows the system to detect and correct errors that would otherwise be introduced by incorrect initial condition assumptions, enabling accurate velocity measurement regardless of whether the object was initially at rest or in motion
Solution Approach 2:
The patent uses asymmetry by employing two different frame rates (asymmetric sampling intervals) rather than symmetric uniform sampling. This asymmetric approach allows the system to detect motion patterns and initial conditions more effectively, improving velocity prediction accuracy without requiring complex additional sensors or mechanisms
Data Source
AI summary
One embodiment relates to a method of velocity prediction using a sensor array. Differential signals are obtained from the sensor array at multiple frame rates. A first velocity prediction is determined from the differential signals at a first frame rate, and a second velocity prediction is determined from the differential signals at a second frame rate. Another embodiment relates to an optical navigation apparatus which includes a sensor array, differential circuitry, driver circuitry, and a signal processing device. The driver circuitry is configured to drive the sensor array and differential circuitry so as to operate at multiple frame rates in an interleaved manner. The signal processing device is configured to compute a first velocity prediction from the differential signals at a first frame rate and to compute a second velocity prediction from the differential signals at a second frame rate. Other embodiments and features are also disclosed.