Overview Objective Background Data Collection CODAmotion Model Equation Design LabVIEW Results Discussion Conclusion
Objective To analyze force and moment data using inverse dynamics to correlate ground reaction forces to forces at the back of the horse that could be transferred to a rider. This could potentially be used to match horses to riders based on their physical abilities
Background o Therapeutic riding, or hippotherapy, is an alternative to traditional physical therapy. o To treat: Cerebral Palsy, Autism, & Muscular Dystrophy. o Previous studies indicate that horseback riding can positively affect the mental state of riders. o No previous scientific research proving the physical benefits of therapeutic riding exists. o In order to verify and optimize any physical benefits, force data at the horse s back is needed to design physical therapy exercises.
Data Collection o Previously collected by Dr. Lopez and her graduate student o What we had to work with: o Force plate o Marker position o Video verification o Basic physical characteristics of the test horse o Our project s objective is to: design a way to analyze this information
Data Collection o Started with approximately 70 trials o Determined valid trials based on: o One hoof on force plate at a time o That hoof must be the horse s left side of the body o Checked for typical ground reaction force plot o Verified using CODAmotion software o Deemed four trials valid Vertical Direction Lateral Direction
CODAmotion Model o Able to import information from force plate and photodiode markers o Created Virtual Markers o Able to export numerical data including: o Forces o Accelerations o Velocities o Marker position o Angles
Biomechanics o Inverse Dynamics: A mathematical process that uses ground reaction forces to determine the moments and forces at joint. o Requires some assumptions: o Joints are frictionless pin-joints. o Segments are rigid with mass concentrated at a constant center of mass. o Treat the distance between markers as the beam or segment o Ignore internal forces due to muscles no way to measure this with the given data o Basic Steps: o Starting with the terminal segment apply the weight of the segment to center of gravity o Find the net force for that segment o Transfer that force to the next segment and repeat the process
Dynamic Equations Using these equations on each individual free-body diagram: F x =ma x, F y =ma y, F z =ma z, M=Iα Here are some of the equations we came up with: Fx=Rgfx-M a a ax M b a bx -M c a cx - M d a dx -M e a ex -M f a fx Fy= Rgfx-W a -M a a ax W b - M b a bx -W c -M c a cx -W d -M d a dx - W e -M e a ex -W f -M f a fx
Equation Formation The values given by CODAmotion are the vector position, acceleration and angular acceleration at each marker. Also, the angles between segments can are given. Treated the bones in the horse s body as segments in a framed structure to calculate our resultant values. The length of segments can be found by subtracting the position of one vector from another. The weight of each bone was found previously as a percentage of total weight. The equations were converted into Microsoft Excel spreadsheets to verify our LabVIEW coding results.
LabVIEW Purpose: To create a user interface Insert Equations into Software Use Mealy Machine Logic Input: Weight, Height, Gait Output: Forces and Moments at different gaits + visual representation of resultant angle.
Image of user interface
Results We developed a software program to model a horse s gait in such a way as to compute the forces that would be exerted at it s back. For our test horse (weight: 395N; height:,) resulting values were: Gait Force (N) Mx (Nm) My (Nm) Mz (Nm) Walk 840.5-616.4-460.3 934.6 Trot 22343 771.8-1196.4 4503.3
Discussion Results compared to a research paper from Cambridge University. Measured the pressure at a horse s back during a trot. One trial horse was reported to be 163cm tall and 300kg in mass. Pressure values were converted to force values and found to be 17,064N. This horse s stats were input into our software program; a force of 16,920N was found. Percent error: 0.85%.
Conclusion We met our objective by creating a software program to analyze raw data and calculate the forces and moments exerted at a horse s back. Our results are valid when compared to published works. Further work must be done to validate the program and apply it to the human body.
Acknowledgments Dr. Mandi Lopez Dr. Marybeth Lima LSU Agricultural Center LSU SVM BAE Department LabVIEW CODAmotion Thank you!
Questions?