Biological Sciences, College of Science, Swansea University, Swansea, United Kingdom.
PLoS One. 2012;7(11):e50556. doi: 10.1371/journal.pone.0050556. Epub 2012 Nov 30.
Animal travel speed is an ecologically significant parameter, with implications for the study of energetics and animal behaviour. It is also necessary for the calculation of animal paths by dead-reckoning. Dead-reckoning uses heading and speed to calculate an animal's path through its environment on a fine scale. It is often used in aquatic environments, where transmission telemetry is difficult. However, its adoption for tracking terrestrial animals is limited by our ability to measure speed accurately on a fine scale. Recently, tri-axial accelerometers have shown promise for estimating speed, but their accuracy appears affected by changes in substrate and surface gradients. The purpose of the present study was to evaluate four metrics of acceleration; Overall dynamic body acceleration (ODBA), vectorial dynamic body acceleration (VDBA), acceleration peak frequency and acceleration peak amplitude, as proxies for speed over hard, soft and inclined surfaces, using humans as a model species.
A general linear model (GLM) showed a significant difference in the relationships between the metrics and speed depending on substrate or surface gradient. When the data from all surface types were considered together, VeDBA had the highest coefficient of determination.
All of the metrics showed some variation in their relationship with speed according to the surface type. This indicates that changes in the substrate or surface gradient during locomotion by animals would produce errors in speed estimates, and also in dead-reckoned tracks if they were calculated from speeds based entirely on a priori calibrations. However, we describe a method by which the relationship between acceleration metrics and speed can be corrected ad hoc, until tracks accord with periodic ground truthed positions, obtained via a secondary means (e.g. VHF or GPS telemetry). In this way, dead-reckoning provides a means to obtain fine scale movement data for terrestrial animals, without the need for additional data on substrate or gradient.
动物的行进速度是一个具有生态学意义的重要参数，它与能量学和动物行为学研究息息相关。同时，它也是推测动物行进路径的重要依据。推测路径的方法是根据动物的行进方向和速度，在微观尺度上计算动物在其所处环境中的路径。这种方法常用于难以进行遥测传输的水生环境中。然而，由于我们在微观尺度上精确测量速度的能力有限，这种方法在陆地动物追踪中的应用受到了限制。最近，三轴加速度计在估计速度方面显示出了良好的应用前景，但它们的准确性似乎受到了基底和表面坡度变化的影响。本研究旨在评估加速度的四个指标；总动态体加速度（ODBA）、向量动态体加速度（VDBA）、加速度峰值频率和加速度峰值幅度，作为在硬表面、软表面和倾斜表面上测量速度的替代指标，以人类作为模型物种。
广义线性模型（GLM）显示，这些指标与速度之间的关系因基底或表面坡度的不同而存在显著差异。当综合考虑所有表面类型的数据时，VDBA 的决定系数最高。
所有指标与速度的关系都根据表面类型而有所变化。这表明，动物在运动过程中基底或表面坡度的变化会导致速度估计出现误差，如果根据预先校准的速度来计算推测路径，也会导致推测路径出现误差。然而，我们描述了一种方法，可以根据加速度指标和速度之间的关系进行特定的校正，直到推测路径与通过次要手段（如 VHF 或 GPS 遥测）获得的周期性地面真实位置相符。通过这种方式，推测路径为陆地动物提供了一种获取微观尺度运动数据的手段，而无需额外的基底或坡度数据。
