Wireless Sensor Integration for Reliable Motion Tracking
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Solution Overview
Problem
Existing wireless communication systems for sensor units face significant data loss during transmission, leading to inaccuracies in motion tracking and orientation measurements due to the need for re-initialization of integration processes, which reduces the accuracy and increases costs by requiring higher bandwidth and more complex systems.
Innovation Solution
A method where the sensor unit mathematically integrates sample values and transmits integrated values along with sequence numbers, allowing for robust real-time data acquisition even with data loss, and enabling autonomous operation without reliance on acknowledgement transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is transmitted wirelessly from sensor unit to master unit, then real-time motion tracking is enabled, but data loss occurs during transmission leading to inaccuracies in motion tracking and orientation measurements
Solution Approach 1:
The sensor unit performs mathematical integration of sensor data locally and transmits only the integrated results (position, velocity, orientation) rather than raw sensor data. This preliminary processing at the sensor unit eliminates the need for re-initialization upon data loss, maintaining measurement precision even when transmission reliability is compromised.
Solution Approach 2:
The patent introduces sequence numbers as an intermediary mechanism to track and identify individual data packets transmitted wirelessly. The master unit uses these sequence numbers to detect missing packets and request retransmission, thereby maintaining data integrity without requiring increased transmission power or bandwidth.
2Reliability
If interpolation is used to handle data loss periods, then data continuity is maintained, but large errors occur especially with large periods of data loss and dynamic signals
Solution Approach 1:
The master unit monitors incoming data packets using sequence numbers and provides feedback by requesting retransmission of specific missing packets. This feedback mechanism ensures data accuracy without relying on error-prone interpolation, as the system actively recovers lost data through targeted retransmission requests.
3Reliability
If acknowledgement and retransmission schemes are implemented, then data loss probability is reduced, but more data must be transmitted over the wireless medium increasing bandwidth requirements
Solution Approach 1:
The patent extracts only the essential information (integrated motion results with sequence numbers) from the raw sensor data for transmission. By transmitting pre-processed integrated values rather than raw sensor streams, the system reduces the volume of data requiring retransmission while maintaining reliability through selective retransmission of critical integrated results.
4Reliability
If transmission power is increased to reduce data packet loss, then data loss probability decreases, but battery consumption increases and transmission power is limited by regulations
Solution Approach 1:
Sequence numbers serve as an intermediary that enables reliable data transmission without increasing power consumption. The master unit uses sequence numbers to identify and request retransmission of specific lost packets, achieving high reliability through intelligent packet management rather than brute-force power increases.
5Reliability
If reserved bandwidth is increased for reducing data loss probability, then data transmission reliability improves, but achievable update rate and maximum number of sensor units deteriorate
Solution Approach 1:
The system extracts and transmits only the essential integrated motion results rather than complete raw sensor data streams. This extraction approach reduces the bandwidth required for each sensor unit, allowing more sensor units to operate simultaneously at high update rates while maintaining reliability through selective retransmission of critical data.
6Ease of operation
If integration process is re-initialized upon data loss, then the system can continue operating, but errors and unknown constants are introduced significantly affecting motion measurement accuracy
Solution Approach 1:
The sensor unit performs preliminary integration of sensor data locally and transmits the integrated results with sequence numbers. This preliminary action ensures that even if transmission occurs, the integrated values represent continuous motion data without requiring re-initialization, thereby maintaining measurement precision while allowing system continuity.
Data Source
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AI summary
The invention relates to a method of enabling a wireless communication between a master unit and at least one sensor unit to be executed within a frame, the at least one sensor unit having an internal data sampling frequency for sampling one or more of its data channels and for storing resulting samples in a buffer memory together with a corresponding sample sequence number, wherein the at least one sensor unit is adapted to transmit an integrated value to the master unit during a portion of the frame, the method comprising the steps of transmitting by the master unit during a master unit portion of the frame a data update request message comprising an identification of an initial sample sequence number from which integration by the at least one sensor unit has to be carried out; integrating by the at least one sensor unit the sample values from the initial sample sequence number to a current sample sequence number; transmitting during a further portion of the frame by the at least one sensor unit the integrated sample value and the identification for the current sample sequence number; receiving by the master unit the integrated sample value and the identification of the current sample sequence number; storing in the master unit at least the identification of the current sample sequence number.