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Coordinating Landings with Compliance
How does surface stiffness affect landing? Cane toads stick the landing across a wide range of surface stiffness, and they rely more on their elbow to land on rigid surfaces while their shoulder puts in more effort on compliant surfaces. Toads use less energy to slow themselves down on compliant surfaces - which explains why trampolines are easier and more fun to jump on compared to jumping on concrete which is a bit of a workout. If you watched the general overview video to the left and want to know more please check out my dissertation defense which goes into greater depth. |
Above are examples of the same toad landing on a rigid surface (left) and the most compliant surface (right; 1 centimeter of displacement per body weight).
The top plots is the limb extension ratio (LER; in magenta) throughout landing, where a LER of 1 would be the arms fully stretched out and a value of 0 having the hands flexed up against the chest.
The middle plots show the magnitude of the impact force (or ground reaction force, GRF; in blue) and the displacement of the platform (orange).
The bottom plots are estimates of the instantaneous joint powers for the wrist, elbow and shoulder joints.
The top plots is the limb extension ratio (LER; in magenta) throughout landing, where a LER of 1 would be the arms fully stretched out and a value of 0 having the hands flexed up against the chest.
The middle plots show the magnitude of the impact force (or ground reaction force, GRF; in blue) and the displacement of the platform (orange).
The bottom plots are estimates of the instantaneous joint powers for the wrist, elbow and shoulder joints.
Next Step
After figuring out toads really don't change much across surface stiffness, I became interested in how the toads may be tuning their muscle activity in preparation for and during landing. Learn more about my second project where I measure the arm muscle activity during jumping & landing.
After figuring out toads really don't change much across surface stiffness, I became interested in how the toads may be tuning their muscle activity in preparation for and during landing. Learn more about my second project where I measure the arm muscle activity during jumping & landing.