Natural example of large energy storage/quick release. Photo Credit: Wallpapers.AndroLib.com
Prompt: Boston Dynamics is a company that specializes in producing robots that can really do the unimaginable. Take Sand Flea. Sand Flea weighs 11 lbs and can jump to heights of up to 30 ft. Such a feat represents a very attractive design goal across all industries for the coming years: the ability to store massive amounts of energy and release it very quickly. Considering that these high energy-density type systems are in fact the way of the future, using what you know about energy come up with either at least 3 ways of storing/quickly releasing a large amount of usable mechanical energy or come up with one way and describe at least 3 ways to look at your solution.
Almost all land animals have the ability to jump and yet this feat is quite difficult to repeat in the robotic world. This is due to the large amounts of energy that need to be stored and then rapidly released to propel the object off the ground. Directly mimicking the crouching and springing action of many animals requires far too many moving parts to be truly feasible for large jumps, Honda’s Asimo does okay though! This is where we have to get creative. We can use a self-contained method of momentum transfer.
Think of hitting a baseball, the batter has to swing the bat very fast before it hits the ball and transfers all of that energy into sending the ball flying over the outfield. Momentum is the product of mass and velocity, so in this analogy the mass of the bat times the speed of the swing would be it’s total momentum. A lot of this momentum energy is transferred to the ball, some of it is lost in sound and heat. The ball has a substantially smaller mass and therefore must have a much greater velocity to balance out the equation.
We can adapt this baseball metaphor to the robotics world by placing a large mass inside our robot, then launching it forward to smash into the front of the robot. In this instance the mass is acting as the bat and the entire device is acting as the ball. There are a few combinations of components we could use to bring this massive energy transfer into the robotics world.
The first would be a spring and mass, contained inside the device, a small electric motor could slowly compress the spring, storing a large amount of elastic potential energy, then suddenly release the mass. The mass would smash into the front of the robot, boosting it forward.
Another method would look similar to firing a gun. Have a combustion chamber filled with an explosive, something storing a large amount of chemical energy, right behind a large mass. Then simply pull the trigger and launch the mass propelling the robot forward.
A third way, and probably my favorite would be adapting a rail gun idea. This would involve coils of wire surrounding a barrel loaded with the large mass. Once electricity is pushed through these wires a strong magnetic field is generated launching the mass forward and thus the robot. Lithium Polymer batteries can store large amounts of energy and release it very fast making this a feasible idea.
Jumping is just one of the applications for quick release of large amounts of energy. But jumping machines look pretty cool and kinda intimidating, for example, check out Boston Dynamic’s Sand Flea.