horse

Touching Ground: Inertial Sensors. Accuracy and precision of spatiotemporal characteristics from fetlock mounted inertial 
measurement units compared to motion capture in horses during over ground walk

Submitted by Emil Olsen

Accurate distal limb spatiotemporal characteristics are useful parameters for a mobile kinematic system to quantify lameness and ataxia in horses. The objective was to compare spatial (position estimates) and temporal characteristics (hoof-on/off and stance time) from fetlock mounted inertial measurement units (IMUs) to motion capture and force plates during walk. Seven horses were walked across a 25 m runway with a central 4.8 m data collection area. We used IMUs (sampling at 200 Hz) that were placed proximal to all four fetlock joints and synchronized to a 12 camera motion capture system sampling at 200 Hz and eight force plates sampling at 500 Hz. We found the temporal characteristics were obtained with an accuracy of -0.02 to -7.38 ms and spatial characteristics with an accuracy of 0.9 to -29.79 mm with good precision for spatial and temporal characteristics, showing the potential for a reliable portable kinematic system based on IMUs.


Listed In: Biomechanics, Gait 




  

    			
Touching Ground: Inertial Sensors.  Accuracy and precision of spatiotemporal characteristics from fetlock mounted inertial 
measurement units compared to motion capture in horses during over ground walk 

		    
        

      Submitted by Emil Olsen
    

    
        	

    		
    		

    			    			    		

    		

    			Accurate distal limb spatiotemporal characteristics are useful parameters for a mobile kinematic system to quantify lameness and ataxia in horses. The objective was to compare spatial (position estimates) and temporal characteristics (hoof-on/off and stance time) from fetlock mounted inertial measurement units (IMUs) to motion capture and force plates during walk. Seven horses were walked across a 25 m runway with a central 4.8 m data collection area. We used IMUs (sampling at 200 Hz) that were placed proximal to all four fetlock joints and synchronized to a 12 camera motion capture system sampling at 200 Hz and eight force plates sampling at 500 Hz. We found the temporal characteristics were obtained with an accuracy of -0.02 to -7.38 ms and spatial characteristics with an accuracy of 0.9 to -29.79 mm with good precision for spatial and temporal characteristics, showing the potential for a reliable portable kinematic system based on IMUs.

    			Listed In: Biomechanics, Gait
    		

    	

        
      









  

    			
Comparison of three lameness quantification methods using a model for presence and alleviation of forelimb heel pain in horses

		    
        

      Submitted by Sandra Starke
    

    
        	

    		
    		

    			    			    		

    		

    			Lameness is an important factor compromising equine performance. Research into lameness biomechanics is extensive, often based on induced lameness. To determine the effect of inducing and alleviating forelimb foot lameness on upper body movement, fetlock angle and ground reaction forces and to examine the necessary stride number to collect, vertical displacement of head, withers and os sacrum was measured in four horses trotting in a straight line. After inducing reversible forelimb heel pain via sole pressure (subjective grade 1-2/10), a palmar digital nerve block (PDNB) was administered. Baseline movement was compared to i) induced lameness, ii) PDNB administration with and without sole pressure and iii) PDNB having worn off. For each condition, subsets of randomly selected strides (n = 5-50) were compared to the ‘true’ mean (n = 60). Head movement detected induced lameness best. Alleviating lameness did not cause systematic movement changes. For mean trajectories within 5 mm of the ‘true’ mean, 15-30 strides were required.

Our project compared for the first time changes to head movement, fetlock angle and vertical ground reaction forces following induced and alleviated forelimb lameness. Results showed that all three objective lameness measurements detected forelimb heel pain, with head movement showing greatest changes and peak vertical force mirroring fetlock angle. All three measures returned to baseline values following a palmar digital nerve block.

    			Listed In: Biomechanics, Gait
    		

    	

        
      









  

    			
Accuracy of Equine Gait Event Detection with Leg-Mounted Inertial Sensors

		    
        

      Submitted by Emil Olsen
    

    
        	

    		
    		

    			    			    		

    		

    			

	INTRODUCTION IMUs are accurate, mobile and cheap alternatives to motion capture cameras. The objective of this study was to evaluate the accuracy of foot-on/off detection in horses using different features derived from trunk and limb mounted IMUs. MATERIALS AND METHODS Four 18 g MTx IMUs were mounted on the fetlock of each limb. Five 10 g IMUs were mounted on the back. IMU data were sampled at 200Hz and synchronised to a 12 camera kinematic system and a force-plate runway. Data were processed with custom written Matlab scripts. The calibrated raw and rotated accelerometer, gyroscope and magnetometer, velocity and displacement data were analysed. RESULTS There was good front-limb (FL) foot-on accuracy and precision (mean less than 30ms bias and SD less than 50ms) for raw Z acceleration, Y angular velocity and X displacement. Z velocity had a poor accuracy (95ms bias) but high precision (SD 15ms). Hind limb (HL) foot-on accuracy and precision were good for raw X acceleration, rotated X acceleration, Z velocity, X displacement and Z velocity of the tuber coxae. FL foot-off accuracy was good for raw X and Z acceleration and rotated X acceleration, Y angular velocity and X velocity of the wither IMU, all with higher imprecision compared to foot-on (max. SD 60ms). For HL foot-off, accuracy and precision were good for Y angular velocity, Z velocity and X displacement and raw X acceleration of the tuber coxae. CONCLUSION IMUs provide an accurate, precise and repeatable method for detection of gait-events in horses.



    			Listed In: Biomechanics, Gait, Previous Winners