Two-types Force Controllers for a Prismatic Actuation Module Redundantly Driven by Multiple Sheet-type Dielectric Elastomer Actuators

A prismatic actuation module redundantly driven by multiple sheet-type dielectric elastomer actuators (DEAs) is developed, and two-types force controllers are proposed to make it control its tensile force with overcoming two representative drawbacks of DEAs. One of two drawbacks of DEAs is a narrow dynamic range of an output force. To cope with this drawback, a force controller that can change the number of activated actuators according to a desired tensile force is proposed. This controller makes it possible to expand the range of output force according to the number of the activated actuators. The other drawback is a short durability, especially breakdown easily occurs when the maximum voltage is steadily inputted. To overcome this drawback, another force controller that can drive the module by activating the only one of several elastomer actuators alternatively depending on time in order for an activating time of the actuator to be short is proposed. This controller makes it possible to reduce the activating time of one actuator with maintaining a desired total output force of the module. First, a prototype of the proposed module is developed, and next, the effectiveness of the proposed two-types force controllers is demonstrated through experiments using the prototype.