Working with hydraulics usually means having a fluid tank and valves. [consciousflesh] does away with both those for his DIY hydraulic artificial muscles. Instead, he uses a pair of muscles, both preloaded with fluid. To contract one, he pumps the fluid into the other, expanding that one, and vice versa. A bidirectional gear pump moves the fluid while also acting as a valve. And flexible materials replace heavy metal cylinders.
As we said, this is a DIY project. He made the muscles by surrounding silicone tubes with aramid fiber sleeves, giving added strength. The blocks at either end are also custom-made. The gear pump is one he purchased and made substantial modifications to, including removing the tank and fixing a brushless DC motor to one end. The final custom piece was a controller board for the motor. A Gerber file, schematic, and technical drawings, along with further details are all on his Hackaday.io page. Meanwhile, check out the load test in the video below as the muscles lift and lower 5 kg (11 lbs) each.
A search of Hackaday shows hydraulic artificial muscles may be rare, so perhaps this will be the first of many. For example, how about replicating how human arm muscles work together, one contracting while the other expands? We’ve seen that done already using pneumatics with [James Hobson’s] exoskeleton arms. Perhaps someone should do it with these pairs of flexible hydraulic muscles?