Improving the accuracy of wearable sensor orientation using a two-step complementary filter with state machine-based adaptive strategy
Bibliographic record
Abstract
Abstract Magnetic and inertial sensors have been widely used in human motion analysis, where accurate orientation estimation is important. Regardless of methods, sensor fusion process faces two major challenges: external acceleration and magnetic disturbance. By analyzing the existing literature, we found that a suitable base sensor fusion algorithm integrated with proper adaptive strategies is essential. In this paper, we first implemented a quaternion-based two-step complementary filter as the base sensor fusion algorithm. Its attitude estimation is immune to magnetic disturbance, and it contains two separate tuning parameters for different conditions of external acceleration and magnetic disturbance. With this base algorithm, we proposed a novel finite state machine-based adaptive strategy. Two state machines were developed to cope with external acceleration and magnetic disturbance. To validate the performance of the proposed sensor fusion method systematically, we developed a battery of tests representing daily-living environments, including acceleration distorted condition, magnetically distorted condition, and combined distorted condition. Also, a real-world experiment was performed to validate the orientation estimation accuracy on foot trajectory calculation. The results demonstrate that the proposed sensor fusion method performs well against external acceleration and magnetic disturbance compared with the existing methods. Especially, the proposed sensor fusion method showed a very high accuracy in the 60 s continuous combined distorted condition, where the root mean square errors of the roll, pitch and yaw were 0.63°, 0.83° and 0.96°, respectively. The accuracy of foot trajectory estimation was significantly improved with the orientation estimated by the proposed method. In conclusion, the proposed sensor fusion method is encouraging for human motion-related applications in daily-living environments. In addition, the proposed state machine based adaptive strategy is simple and robust, and can be easily integrated into other base sensor fusion algorithms.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".