Abstract
A wearable assistive robot must continuously estimate terrain, locomotion mode, gait phase, and walking speed. These quantities are commonly addressed by separate, terrain-specific models, with datasets rarely collected under a common protocol. This paper presents a visuo-inertial framework that connects these estimates through a causal pipeline using a chest-mounted camera and four lower-limb inertial measurement units (IMUs). Anticipatory Terrain Perception (ATP) classifies incoming terrain with 96.3% accuracy and anticipates terrain transitions by 1.46 s on average. Terrain-Aware Locomotion Mode Identification (TALMI) achieves 93.7% and 98.8% accuracy for its level-ground and stairs experts respectively, with mean transition latencies being below 200 ms. The relevant TALMI posterior is retained as a Probabilistic Locomotion Context (PLC) vector and provided to a shared Gait Kinematic Encoder (GKE), which supports 50-Hz bilateral gait-phase estimation and 2-Hz walking-speed estimation. Leave-one-subject-out evaluation yields gait-phase RMSEs of 1.75%, 2.97%, and 4.55% for level walking, stair ascent, and stair descent respectively while estimating speed over 3.5-5.5 km/h with a RMSE of 0.218 km/h. All inertial sensing based models use sensor-fused Euler angles as input rather than raw accelerometer and gyroscope signals, reducing dependence on sensor mounting variation.
Chinese Translation
可穿戴辅助机器人必须持续估计地形、运动模式、步态阶段和行走速度。这些量通常通过独立的、特定于地形的模型来处理,而数据集很少在统一的协议下收集。本文提出了一种视觉惯性框架,通过一个胸部安装的摄像头和四个下肢惯性测量单元(IMU)使用因果管道连接这些估计。预期地形感知(Anticipatory Terrain Perception, ATP)以96.3%的准确率对即将到来的地形进行分类,并平均提前1.46秒预测地形过渡。地形感知运动模式识别(Terrain-Aware Locomotion Mode Identification, TALMI)在其平地和楼梯专家中分别达到了93.7%和98.8%的准确率,平均过渡延迟低于200毫秒。相关的TALMI后验被保留为概率运动上下文(Probabilistic Locomotion Context, PLC)向量,并提供给共享的步态运动编码器(Gait Kinematic Encoder, GKE),该编码器支持50赫兹的双侧步态阶段估计和2赫兹的行走速度估计。留一法评估的步态阶段均方根误差(RMSE)分别为平地行走1.75%、楼梯上升2.97%和楼梯下降4.55%,同时在3.5-5.5公里/小时的速度估计中,RMSE为0.218公里/小时。所有基于惯性传感的模型使用传感器融合的欧拉角作为输入,而不是原始的加速度计和陀螺仪信号,从而减少了对传感器安装变化的依赖。