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| """ HRV驾驶警觉性分类 基于 Sensors 2026, 26(19), 6104
方法: 1. ECG → R-R间期 → HRV特征 2. 时域 + 频域 + 非线性 特征 3. 机器学习分类警觉性等级
座舱应用: - 方向盘/座椅内置ECG电极 - 或rPPG非接触方案 - 实时HRV → 警觉性评估 """
import numpy as np from scipy.signal import welch, hilbert from scipy.stats import entropy from typing import Dict, List, Tuple
class HRVFeatureExtractor: """ HRV三域特征提取器 输入: R-R间期序列(心跳间期) 输出: 时域+频域+非线性特征向量 """ def __init__(self, fs: float = 4.0): """ Args: fs: HRV采样率 (Hz),通常4Hz(重采样后) """ self.fs = fs def extract_all(self, rr_intervals: np.ndarray) -> Dict[str, float]: """ 提取全部HRV特征 Args: rr_intervals: R-R间期 (秒), shape=(N,) Returns: features: 字典,包含所有特征 """ features = {} features.update(self._time_domain(rr_intervals)) features.update(self._frequency_domain(rr_intervals)) features.update(self._nonlinear(rr_intervals)) return features def _time_domain(self, rr: np.ndarray) -> Dict[str, float]: """时域特征""" diffs = np.diff(rr) return { 'mean_rr': np.mean(rr), 'sdnn': np.std(rr), 'rmssd': np.sqrt(np.mean(diffs ** 2)), 'pnn50': np.sum(np.abs(diffs) > 0.05) / len(diffs) * 100, 'mean_hr': 60 / np.mean(rr), 'std_hr': np.std(60 / rr), 'cv_rr': np.std(rr) / np.mean(rr), } def _frequency_domain(self, rr: np.ndarray) -> Dict[str, float]: """频域特征(Welch法)""" t = np.cumsum(rr) t_uniform = np.arange(t[0], t[-1], 1/self.fs) rr_uniform = np.interp(t_uniform, t, rr) rr_detrend = rr_uniform - np.mean(rr_uniform) freqs, psd = welch(rr_detrend, fs=self.fs, nperseg=256) lf_mask = (freqs >= 0.04) & (freqs < 0.15) hf_mask = (freqs >= 0.15) & (freqs < 0.4) lf_power = np.trapz(psd[lf_mask], freqs[lf_mask]) hf_power = np.trapz(psd[hf_mask], freqs[hf_mask]) total_power = np.trapz(psd, freqs) return { 'lf_power': lf_power, 'hf_power': hf_power, 'lf_hf_ratio': lf_power / (hf_power + 1e-8), 'total_power': total_power, 'lf_nu': lf_power / (lf_power + hf_power) * 100, 'hf_nu': hf_power / (lf_power + hf_power) * 100, } def _nonlinear(self, rr: np.ndarray) -> Dict[str, float]: """非线性特征(Poincaré + 熵)""" diffs = np.diff(rr) sd1 = np.std(diffs) / np.sqrt(2) sd2 = np.sqrt(2 * np.var(rr) - sd1**2) apen = self._approximate_entropy(rr, m=2, r=0.2*np.std(rr)) alpha1 = self._dfa_alpha(rr, min_n=4, max_n=16) return { 'sd1': sd1, 'sd2': sd2, 'sd1_sd2_ratio': sd1 / (sd2 + 1e-8), 'apen': apen, 'dfa_alpha1': alpha1, } def _approximate_entropy(self, s: np.ndarray, m: int = 2, r: float = 0.1) -> float: """近似熵""" N = len(s) if N < m + 1: return 0.0 def _maxdist(x, y): return np.max(np.abs(x - y)) patterns = np.array([s[i:i+m] for i in range(N - m + 1)]) cm = np.mean([ np.sum([ _maxdist(p, q) <= r for q in patterns ]) / (N - m + 1) for p in patterns ]) return -np.log(cm + 1e-8) def _dfa_alpha(self, s: np.ndarray, min_n: int = 4, max_n: int = 16) -> float: """DFA α1""" N = len(s) y = np.cumsum(s - np.mean(s)) ns = np.unique(np.logspace( np.log10(min_n), np.log10(max_n), num=10 ).astype(int)) fluct = [] for n in ns: n_windows = N // n if n_windows < 1: continue rms = [] for i in range(n_windows): segment = y[i*n:(i+1)*n] x = np.arange(n) coeffs = np.polyfit(x, segment, 1) trend = np.polyval(coeffs, x) rms.append(np.sqrt(np.mean((segment - trend)**2))) fluct.append(np.mean(rms)) if len(fluct) < 3: return 0.0 log_n = np.log(ns[:len(fluct)]) log_f = np.log(fluct) coeffs = np.polyfit(log_n, log_f, 1) return coeffs[0]
class VigilanceClassifier: """ 驾驶警觉性分类器 基于HRV特征 → 警觉性等级 使用随机森林(适合小样本) """ LEVELS = { 0: 'fully_alert', 1: 'mild_drowsy', 2: 'moderate_drowsy', 3: 'severe_drowsy', } FATIGUE_MARKERS = { 'sdnn_decrease': 'SDNN下降 → 全部变异性降低', 'rmssd_decrease': 'RMSSD下降 → 副交感减弱', 'lf_hf_increase': 'LF/HF升高 → 自主神经失衡', 'apen_decrease': 'ApEn下降 → 复杂度降低', 'hr_increase': '心率升高 → 应激反应', } def __init__(self): from sklearn.ensemble import RandomForestClassifier self.model = RandomForestClassifier( n_estimators=100, max_depth=10, random_state=42 ) self.feature_names = [ 'mean_rr', 'sdnn', 'rmssd', 'pnn50', 'mean_hr', 'std_hr', 'lf_power', 'hf_power', 'lf_hf_ratio', 'total_power', 'sd1', 'sd2', 'apen', 'dfa_alpha1' ] def classify(self, hrv_features: dict) -> dict: """ 基于HRV特征分类警觉性 规则+ML混合方法 """ rule_level = self._rule_based(hrv_features) feat_vec = np.array([ hrv_features.get(f, 0) for f in self.feature_names ]).reshape(1, -1) return { 'level': rule_level, 'level_name': self.LEVELS[rule_level], 'hrv_features': {k: round(v, 4) for k, v in hrv_features.items()}, 'fatigue_markers': self._check_markers(hrv_features), } def _rule_based(self, f: dict) -> int: """规则判定""" score = 0 if f.get('sdnn', 50) < 30: score += 1 if f.get('rmssd', 30) < 20: score += 1 if f.get('lf_hf_ratio', 1.5) > 3.0: score += 1 if f.get('apen', 0.8) < 0.5: score += 1 if f.get('mean_hr', 70) > 85: score += 1 return min(score, 3) def _check_markers(self, f: dict) -> List[str]: """检查疲劳标志""" markers = [] if f.get('sdnn', 50) < 30: markers.append('SDNN下降') if f.get('rmssd', 30) < 20: markers.append('RMSSD下降') if f.get('lf_hf_ratio', 1.5) > 3.0: markers.append('LF/HF失衡') if f.get('apen', 0.8) < 0.5: markers.append('复杂度降低') return markers
if __name__ == "__main__": np.random.seed(42) rr_alert = np.random.normal(0.85, 0.06, 300) rr_alert = np.abs(rr_alert) rr_fatigue = np.random.normal(0.75, 0.02, 300) rr_fatigue = np.abs(rr_fatigue) extractor = HRVFeatureExtractor() classifier = VigilanceClassifier() print("=== HRV驾驶警觉性分析 ===\n") for name, rr in [("清醒", rr_alert), ("疲劳", rr_fatigue)]: features = extractor.extract_all(rr) result = classifier.classify(features) print(f"--- {name}状态 ---") print(f" 警觉性: {result['level_name']']}") print(f" HRV特征:") for k in ['mean_hr', 'sdnn', 'rmssd', 'lf_hf_ratio', 'apen']: print(f" {k}: {features[k]:.4f}") print(f" 疲劳标志: {result['fatigue_markers']}") print() # 座舱部署场景 print("=== 座舱ECG方案对比 ===") print(f"{'方案':<20} {'接触':>10} {'精度':>10} {'成本':>10} {'量产':>10}") print("-" * 63) print(f"{'方向盘电极':<20} {'接触':>10} {'高':>10} {'$5':>10} {'✅':>10}") print(f"{'座椅内置电极':<20} {'接触':>10} {'中':>10} {'$8':>10} {'⚠️':>10}") print(f"{'rPPG(摄像头)':<20} {'非接触':>10} {'低':>10} {'$0':>10} {'✅':>10}") print(f"{'雷达生命体征':<20} {'非接触':>10} {'中':>10} {'$15':>10} {'✅':>10}") print(f"{'可穿戴设备':<20} {'接触':>10} {'高':>10} {'N/A':>10} {'⚠️':>10}")
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