How it Works

The TöltSense system uses a network of four sensors on the lower limbs (cannon bones) of the horse to continuously measure acceleration and rotation rate. These data are streamed to the mobile phone running the TöltSense app (typically in the pocket of the rider), where the hoof on/off times are calculated. For each leg and every step we can define a ‘stride’ object which begins with a hoof-on time, has a stance phase lasting until the hoof-off time, and a swing phase ending with the next hoof-on where the current stride ends and the next one begins. Every stride of every leg can then be placed in a temporal sequence from which we are able to infer what gait the horse is showing and how well that gait is being performed in terms of rhythm, evenness, and suspension.

The sensors are custom designed circuit boards comprising a 6-axis IMU chip, a dual core processor supporting both BLE and WiFi, a Qi standard wireless charging circuit, a capacitative touch pad for wake-up control, an RGB LED for status indication, and a 500 mAh LiPo battery supporting up to 2 hours of constant operation. The circuitry is protected by an IP65 plastic enclosure measuring 5.5 cm x 4.5 cm x 1.7 cm and the units are held in place with neoprene harnesses. This material is stretchy, durable, and soft and does not interfere with the horse’s movements. Moreover, it protects the sensors from the worst of the mud, water, and possible impacts meaning they can be deployed in virtually all conditions whether wet or dry, indoors or outside.

In preparation for a training session the sensors must first be woken up by touching, after which they start looking for a signal from the app. When the app is launched an advertisement is sent using BLE which tells the sensor network that the app and its services are available and then the sensors form their own WiFi network. As soon as the TöltSense network is created the clocks will be synchronised to within 5 ms of each other, and after this happens the network is available for the app to connect. Once the app is connected a service monitors the sensor clocks for discrepancies and will make adjustments for any drift that may occur, thus ensuring the synchronisation is maintained. In addition to streaming motion data, the sensors also report on their battery level and on-chip temperature.

Phone-only horse training apps such as Equilab, brilliant as they are, classify gaits by means of a machine-learning based model operating on the outputs of the phone’s on-board sensors. This approach is undoubtedly very convenient for the rider, since it only requires the phone in their pocket, but is fundamentally limited in two ways. First, the accuracy of the gait classification is not always satisfactory, particularly when dealing with gaited horses like Icelandics, whose tölt is often misclassified as either trot or canter. Second, such apps struggle to say anything meaningful about the quality of the gait being performed. For example, if one is interested in achieving a certain degree of suspension in trot you have to track the amount of time in each cycle where all limbs are in swing phase together. A phone in your pocket has no chance of measuring this.

TöltSense, by contrast, takes the stride data and compares it with widely accepted definitions of the gaits framed in terms of properties that TöltSense can measure or calculate directly. These are things like the sequence and rhythm of footfalls, the presence or absence of a suspensory phase, the positioning of any suspensory phase in the cycle, the relative duty factor of the hind legs vs the front, whether or not any limbs land at the same time, presence of a single, double or triple leg support phase, etc. These factors all have relevance for the perceived quality of the gait as well. Tölt, for example, is meant to be a perfectly even sequence of four individual footfalls (like walk, in that regard). But if the relative timing between diagonals gets too short the tölt is said to be ‘trotty’. In a similar fashion if the relative timing between laterals gets too short the tölt is said to be ‘pacey’. These labels make sense because the tölt, in terms of its rhythm, is precisely in the middle of a continuum between trot and pace. Suspension also has great importance for the perceived quality of the trot, canter and flying pace. The suspensory moment ought to be clearly visible, which in practical terms means it ought to be at least 0.1 seconds. A trot with no visible suspension will be marked poorly in an oval track test.