Multimode Small-Size Pneumatic Motors Based on Rigid-Flexible Coupling Structure

Applications of the existing pneumatic motors to complex environments and tasks are limited by single mode, large size, and poor output performance in speed and power. This study presents a new multimode small pneumatic motor. It has both the continuous rotation mode and stepper mode, which could be rapidly switched by regulating the input signal to the ports. The motors, composed of only seven parts, have the characteristics of small size, lightweight, and low manufacturing cost. Motors with different output performance and stepping accuracies could be obtained by configuring the numbers of roller and tube. The effects of the structural parameters on the output characteristics were modeled. Three 40 mm size motors with different configurations were developed to test the performance and verify the validity of the models. While they could produce the maximum output speed of 4600 r/min, the torque of 72 mNm, the power of 11.8 W in the continuous mode, the maximum stepping error was approximately 1.5(degrees) in the stepper mode. To demonstrate the superior performance, the motors with a dimension of Phi 10 x 10 mm were developed and applied in an in-pipe inspection robot for the pipe with diameter of 25.4 mm, a pneumatic quadcopter, and a pneumatic modular manipulator joint.