Comparison of Trotting Stance Detection Methods from an Inertial Measurement Unit Mounted on the Horse’s Limb

Abstract

The development of on-board sensors, such as inertial measurement units (IMU), has made it possible to develop new methods for analyzing horse locomotion to detect lameness. The detection of spatiotemporal events is one of the keystones in the analysis of horse locomotion. This study assesses the performance of four methods for detecting Foot on and Foot off events. They were developed from an IMU positioned on the canon bone of eight horses during trotting recording on a treadmill and compared to a standard gold method based on motion capture. These methods are based on accelerometer and gyroscope data and use either thresholding or wavelets to detect stride events. The two methods developed from gyroscopic data showed more precision than those developed from accelerometric data with a bias less than 0.6% of stride duration for Foot on and 0.1% of stride duration for Foot off. The gyroscope is less impacted by the different patterns of strides, specific to each horse. To conclude, methods using the gyroscope present the potential of further developments to investigate the effects of different gait paces and ground types in the analysis of horse locomotion.

Human and Animal Motion Tracking Using Inertial Sensors

“…The second set of two research papers is dedicated to equine science, analyzing the horse locomotion phase [8] and estimating the speed per strike [9].…”

“…The first concerns the detection of the stance of the horse locomotion and the stride duration of the foot on and off [8]. In their article, the authors presented an inertial sensor solution located at the distal part of the lower limb.…”

The Protraction and Retraction Angles of Horse Limbs: An Estimation during Trotting Using Inertial Sensors

“…Many riders miss the appearance of asymmetry in the horse and are only alarmed when lameness is present [ 21 ]. The development of on-board measurement methods of the horse’s locomotion at work would also provide a tool for riders and trainers to detect the first signs of irregularities of the gait [ 22 , 23 ]. Thus, the appearance of several locomotor problems could be limited and treated more quickly by the veterinarian.…”

“…Although precise, these systems involve laboratory use, which limits their applications [ 28 ]. More recently, studies have focused on the use of inertial measurement units (IMUs) to measure the protraction and retraction angles of horse limbs [ 12 , 15 , 22 , 23 , 24 ]. The use of IMUs, more versatile and pervasive [ 28 ], can then allow these measurements under the normal working conditions of the horse [ 22 ].…”

“…The orientation of the limb can be obtained by integrating the angular velocity of the gyroscopic signal over time, paying attention to the accumulation of drift errors [ 36 ]. In order to limit the risk of drift, the integration is carried out over reduced time windows [ 37 ], corresponding in our study with the duration of the stride or stance phases (641.5 m/s and 201.5 m/s on average, respectively, at a 4 m/s trot [ 23 ]) for the measurements of the protraction/retraction movements of the limb during the stride or the stance. The gyroscopic data are recorded in the IMU’s local coordinate system.…”