1) Fiber-reinforced actuator
This rotary is rather simple in structure. One angular chamber, fiber reinforcement and two connected thick plates make this. Once the air is pumped into the chamber, the actuator will expand to larger angle. Here, the fiber is to keep the chamber from inflating laterally and backward too much so that more deformation will contribute to more increase in angle.
2) Multi-bag rotary actuator
This is also a well-developed rotary type of pneumatic actuator with bidirectional function. By inflating the chamber/bags, the actuator rotates with high power output. The chambers/bags are made of polyurethane film or even fire flat hose.
3) Plastic-reinforced multi-chamber rotary actuator
The figure below shows the new rotary actuator to be built in our lab soon. It is made of soft silicone rubber and plastic sheets. All the chambers in different segments are connected by the air way in different segments and the hole on the plastic sheet. The plastic sheet will restrict the chamber to swelling in the directions parallel to the sheet surface, in this way, the actuator will rotate more angle.
Note:
All the actuators mentioned above are just the representatives of the hundreds of pneumatic bending actuators out there.