Performance-Optimized Dielectric Elastomer Actuator System with Scalable Scissor Linkage Transmission

Abstract

Thanks to their outstanding properties, in the last few years Dielectric Elastomer Actuators (DEAs) have increasingly attracted the interest of the scientific community and generated a surge in the effort devoted to their industrialization. Compared to conventional actuator systems, DEAs are based on inexpensive and widely available polymeric materials, which make them potentially attractive from a market perspective. However, DEA systems with a given layout and dimensions have a fixed force-stroke response that is only suitable for a specific load profile. This leads to a wide variety of designs combined with small production volumes and high costs, limiting the competitive advantage. This work addresses this issue by proposing a combination of DEA systems with compliant scissor linkage transmission mechanisms, which provide linear stroke and force scaling and simultaneously maintain performance optimization by leaving the convertible energy density of the DEA unaffected. For this purpose, three systems are designed, based on a same strip-shaped DEA combined with inclined buckled beam biasing mechanisms. Two of the systems are coupled with scissor linkages that offer transmission ratios of 3:1 and 1:3, respectively, to adapt the system to different load profiles. The system design is explained in detail, and the functional principle is validated through experiments.

Low profile dielectric elastomer actuator system with unibody compliant joint transmission

“…The basic concept of coupling a DEA-based linear actuator with a linear transmission mechanism in order to increase the stroke or force of the actuator depending on the load is already explained in detail in [15]. Hence, only the relevant findings are summarized in this section briefly with help of Figure 1.…”

“…The scissor linkage (also called pantograph) allows linear motion to be scaled up and down through a lever-like joint arrangement. It is based on the planar four-bar mechanism, whose geometry and kinematics are described in detail in many standard works on mechanics and robotics [15,16]. A non-inverting variant of this mechanism, which is used in this work, is schematically illustrated in a stroke magnifying configuration in Figure 1b (transmission ratio 𝑖 > 1), and in a in configuration in Figure 1c (transmission ratio 0 < 𝑖 < 1).…”

“…This section explains the design and construction of the individual components such as SIP, NBS and linkage transmission, as well as the assembly of the overall system, and provides information on materials and manufacturing. Since the general layout and design are adopted from [15], only the main aspects and differences are explained in the following.…”

“…To achieve this for DEA technology, previous work [15] has proposed to couple DEA systems with scissor linkage transmission mechanisms to manipulate their force-displacement characteristics with a configurable transmission ratio. With this approach, identical DEA designs can be used to actuate different load profiles, potentially significantly increasing unit quantities, and reducing development and production costs.…”

“…Following the above approach of former work [15], this paper also presents a SIP-NBS system coupled with either a strokemagnifying or stroke reducing unibody scissor linkage transmission based on compliant joints and rigid bars. However, in contrast, the emphasis here is on bringing the basic concept closer to a more realistic application.…”