Pneumatic Rotary Vane Joints Lend A Gentle Helping Hand

Festo has released a video showing the workings of their BionicCobot, a pneumatic robot arm developed for lending a helping hand to humans at a workstation. Since it works intimately with humans, it has to be safe, producing no harmful movements, and reacting when encountering an obstacle such as an arm containing delicate human bone. This it does using pneumatics and rotary vanes.

Rotary vane in action

The arm has seven degrees of freedom, three in the shoulder, one in the elbow, another in the lower arm, and two in the wrist. But you won’t find any electric motor or gears. Instead each contains a rotary vane. Compressed air pushes on both sides of the vane. If the air pressure is the same on both sides of the vane then it doesn’t rotate. But with more pressure on one side than the other, the vane rotates. This is much like in a human arm, where two muscles work together to bend the arm, one muscle contracts while the other relaxes. Together they’re referred to as an antagonistic pair. In addition, each joint has a circuit board with two pressure sensors for monitoring the joint.

Using pneumatics, if an obstacle is encountered, the pressure can be released, making it instantly safe. And air being compressible, the joint can behave like a spring, further adding to the safeness. By controlling the pressure, the spring can be made more or less tense.

You can see it in action in the video below the break, along with more details such as how they use ROS, the popular, open system Robot Operating System which we’ve seen here a lot before, along with their Festo valve bank, one of which our own [James Hobson] used for his slick elysium exoskeleton. The video also covers how they handled running the hoses, the kinematics and the UI software.

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