Most of you know that hydraulics can integrate with robotic systems for offering maximum performance. One such famous robot with hydraulic implementation is BigDog. Here, we can find more interesting facts regarding this quadruped robot implemented in the defence sector for assisting soldiers in carrying their gear. The BigDog robot can walk/run at a maximum speed of 10km/hr and carry up to 150kg loads. Other benefits of this robot are climbing muddy hiking trails and slopes with an angle up to 35°, walking across rubble, etc. Also, this robot is suitable for indoor/outdoor applications, and the most important is its efficiency in terrain, water, and snow environment.
What is BigDog? I hope that you can answer this question quickly now. Next, we can understand the history and specifications of this robot BigDog. This quadruped military robot funded by Defense Advanced Research Projects Agency (DARPA) and was manufactured in 2005 by Boston Dynamics, Foster-Miller, NASA JPL, and the Harvard University Concord Field Station. This robot serving as a robotic pack mule is 3feet long, 2.5feet tall, and weighs 240pounds. Also, this unmanned-legged robot contains onboard systems for providing power, actuation, sensing, controls, and communications.
As mentioned, BigDog is a legged robot, and this legged structure will make it superior to wheeled/tracked vehicles. Each of the robot legs are powered by hydraulics, and its movement depends on output signals from sensors. Sensors can also be integrated for measuring internal parameters like oil temperature, hydraulic pressure, engine function, and more.
Now, we can talk about our specific topic. I.e. hydraulics for the robot BigDog. This robotic system has a hydraulic pump and contains 16 custom hydraulic actuators. The movement of the piston-cylinder assemblies in the actuator will decide how each of the legs are moved independently. The sensor subsystem will send signals like the joint position, joint force, ground contact, ground load, etc., to the onboard computer. The robotic leg movement is controlled based on this input signal and provides maximum safety and efficiency.
The BigDog legs contain four hydraulic actuators(low-friction hydraulic cylinders) that operate separately based on the controls, enabling BigDog movement in the most challenging conditions. This robot will include a 15hp two-stroke internal combustion engine that pressurizes the hydraulic fluid using the hydraulic pump. The design of the BigDog system has a 3000psi variable displacement hydraulic pump and a 2-stage electro-hydraulic servo valve. The pressurized hydraulic oil will make the actuator piston move forward and backwards and then create the required motion. The hydraulic system also contains different components like heat exchangers, accumulators, filters, manifolds, and plumbing components.