Cai Xi, Han Guang, Song Xin, Wang Jinkuan
College of Information Science and EngineeringNortheastern University.
College of Information Science and Engineering, Northeastern University, Shenyang, China.
IEEE Trans Biomed Eng. 2017 Nov;64(11):2618-2627. doi: 10.1109/TBME.2017.2653246.
single-camera-based gait monitoring is unobtrusive, inexpensive, and easy-to-use to monitor daily gait of seniors in their homes. However, most studies require subjects to walk perpendicularly to camera's optical axis or along some specified routes, which limits its application in elderly home monitoring. To build unconstrained monitoring environments, we propose a method to measure step length symmetry ratio (a useful gait parameter representing gait symmetry without significant relationship with age) from unconstrained straight walking using a single camera, without strict restrictions on walking directions or routes.
according to projective geometry theory, we first develop a calculation formula of step length ratio for the case of unconstrained straight-line walking. Then, to adapt to general cases, we propose to modify noncollinear footprints, and accordingly provide general procedure for step length ratio extraction from unconstrained straight walking.
Our method achieves a mean absolute percentage error (MAPE) of 1.9547% for 15 subjects' normal and abnormal side-view gaits, and also obtains satisfactory MAPEs for non-side-view gaits (2.4026% for 45°-view gaits and 3.9721% for 30°-view gaits). The performance is much better than a well-established monocular gait measurement system suitable only for side-view gaits with a MAPE of 3.5538%.
Independently of walking directions, our method can accurately estimate step length ratios from unconstrained straight walking.
This demonstrates our method is applicable for elders' daily gait monitoring to provide valuable information for elderly health care, such as abnormal gait recognition, fall risk assessment, etc.
single-camera-based gait monitoring is unobtrusive, inexpensive, and easy-to-use to monitor daily gait of seniors in their homes. However, most studies require subjects to walk perpendicularly to camera's optical axis or along some specified routes, which limits its application in elderly home monitoring. To build unconstrained monitoring environments, we propose a method to measure step length symmetry ratio (a useful gait parameter representing gait symmetry without significant relationship with age) from unconstrained straight walking using a single camera, without strict restrictions on walking directions or routes.
according to projective geometry theory, we first develop a calculation formula of step length ratio for the case of unconstrained straight-line walking. Then, to adapt to general cases, we propose to modify noncollinear footprints, and accordingly provide general procedure for step length ratio extraction from unconstrained straight walking.
Our method achieves a mean absolute percentage error (MAPE) of 1.9547% for 15 subjects' normal and abnormal side-view gaits, and also obtains satisfactory MAPEs for non-side-view gaits (2.4026% for 45°-view gaits and 3.9721% for 30°-view gaits). The performance is much better than a well-established monocular gait measurement system suitable only for side-view gaits with a MAPE of 3.5538%.
Independently of walking directions, our method can accurately estimate step length ratios from unconstrained straight walking.
This demonstrates our method is applicable for elders' daily gait monitoring to provide valuable information for elderly health care, such as abnormal gait recognition, fall risk assessment, etc.
基于单摄像头的步态监测具有不引人注意、成本低廉且易于使用的特点，可用于监测老年人在家中的日常步态。然而，大多数研究要求受试者垂直于摄像头光轴行走或沿特定路线行走，这限制了其在老年人居家监测中的应用。为构建无约束的监测环境，我们提出一种方法，可利用单个摄像头从无约束的直线行走中测量步长对称比（一个表示步态对称性且与年龄无显著关系的有用步态参数），对行走方向或路线无严格限制。
根据射影几何理论，我们首先推导了无约束直线行走情况下步长比的计算公式。然后，为适应一般情况，我们提出对非共线足迹进行修正，并相应地给出了从无约束直线行走中提取步长比的一般步骤。
我们的方法对15名受试者的正常和异常侧视图步态实现了平均绝对百分比误差（MAPE）为1.9547%，对于非侧视图步态也获得了令人满意的MAPE（45°视图步态为2.4026%，30°视图步态为3.9721%）。该性能远优于仅适用于侧视图步态的成熟单目步态测量系统，其MAPE为3.5538%。
与行走方向无关，我们的方法能够从无约束的直线行走中准确估计步长比。
这表明我们的方法适用于老年人日常步态监测，可为老年保健提供有价值的信息，如异常步态识别、跌倒风险评估等。
基于单摄像头的步态监测具有不引人注意、成本低廉且易于使用的特点，可用于监测老年人在家中的日常步态。然而，大多数研究要求受试者垂直于摄像头光轴行走或沿特定路线行走，这限制了其在老年人居家监测中的应用。为构建无约束的监测环境，我们提出一种方法，可利用单个摄像头从无约束的直线行走中测量步长对称比（一个表示步态对称性且与年龄无显著关系的有用步态参数），对行走方向或路线无严格限制。
根据射影几何理论，我们首先推导了无约束直线行走情况下步长比的计算公式。然后，为适应一般情况，我们提出对非共线足迹进行修正，并相应地给出了从无约束直线行走中提取步长比的一般步骤。
我们的方法对15名受试者的正常和异常侧视图步态实现了平均绝对百分比误差（MAPE）为1.9547%，对于非侧视图步态也获得了令人满意的MAPE（45°视图步态为2.4026%，30°视图步态为3.9721%）。该性能远优于仅适用于侧视图步态的成熟单目步态测量系统，其MAPE为3.5538%。
与行走方向无关，我们的方法能够从无约束的直线行走中准确估计步长比。
这表明我们的方法适用于老年人日常步态监测，可为老年保健提供有价值的信息，如异常步态识别、跌倒风险评估等。
