Application Cases

Experiment Name: Research on Fast-Rotating Soft Actuators

Experiment Purpose: A novel type of rotatable soft actuator based on piezoelectric vibration drive is proposed. The force and motion mechanism of the actuator under the action of the excitation force were analyzed through theory and finite element simulation. The influence of the amplitude and angular frequency of the applied excitation force on the rotational performance of the actuator was studied, and the finite element simulation results were verified through experiments.

Testing Equipment: ATA-2042 high-voltage amplifier, signal generator, digital camera, two-dimensional lift stage, etc.

Soft actuators are a type of flexible, large-deformation drive system, distinct from traditional rigid actuators composed of rigid components such as motors, bearings, gears, and hinges. Typically made from soft materials, soft actuators theoretically possess infinite degrees of freedom, can withstand large deformations, exhibit continuous deformation, and provide compliant contact. Therefore, soft actuators have significant advantages in handling fragile objects and moving in complex, unstructured environments.

Drawing inspiration from limbless animals, a novel type of rotatable soft actuator based on piezoelectric vibration drive is proposed. The force and motion mechanism of the actuator under the action of the excitation force were analyzed through theory and finite element simulation. The influence of the amplitude and angular frequency of the applied excitation force on the rotational performance of the actuator was studied, and the finite element simulation results were verified through experiments.

In the experiment, a rotational soft actuator was first constructed, consisting of a vibration source and a soft bristle structure. A suitable vibration source can provide the appropriate excitation force for this actuator. The experiment requires a vibration source that can produce high-frequency vibrations and has a certain driving force.

The bristle robot driven by vibration uses the vibration generated by piezoelectric bimorphs to drive the bristles to move up and down. Due to the inclined arrangement of the bristles, an asymmetric friction force (forward friction force is greater than backward friction force) is generated during the up and down vibration process, driving the robot to move in one direction. In this paper, an array of inclined bristles is arranged along the circumferential direction. When the circular end face of the rotating soft structure is subjected to a uniformly distributed periodic excitation force, the structure generates a friction force along the direction of the bristle inclination, thereby providing a rotational driving force.

A test platform for the rotational soft actuator was set up. The voltage amplifier first amplifies the excitation signal emitted by the signal generator and then applies the excitation signal to the actuator. To measure the rotation angle of the actuator, an arrow is marked on the actuator and placed on graph paper, where each small grid represents an angle of 15°. A digital camera is used to synchronously capture the motion process of the actuator, and then the rotation speed of the actuator is calculated based on the time required for the actuator to complete one full rotation.

The motion mechanism of the rotational soft actuator was analyzed through motion modeling and numerical simulation, and its rotational performance was studied experimentally. The actuator generates vibration through piezoelectric bimorphs to drive the bristles of the rotating soft structure to periodically bend down and bounce up. The static friction force generated during the downward bending motion of the bristles is greater than the kinetic friction force generated during the upward bouncing motion, thus creating a net driving force. This, in turn, enables rapid rotation under the action of high-frequency excitation force. When a rotational soft actuator is subjected to a voltage VP−P of 400V and a frequency of 1400Hz, its rotational speed can reach 118.3 revolutions per minute (r/min). Such rotational soft actuators are expected to find applications in the design and development of high-performance mobile robots, robotic arms, and artificial joints.

Voltage Amplifier Recommendation: ATA-2042

Figure: Specification Parameters of the ATA-2042 High-Voltage Amplifier

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