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Electroactive Polymers for Robotic Applications - Kim & Tadokoro (Eds.) Part 4

Tham khảo tài liệu 'electroactive polymers for robotic applications - kim & tadokoro (eds.) part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Robotic Applications of Artificial Muscle Actuators 53 Prestretching Electrodes Output terminal Insulating film Figure 3.2. Fabrication of antagonistically driven actuator Prestretching Frame Prestretched elastomer In this design the actuator is actually composed of a single prestretched elastomer film affixed to a rigid square frame which provides uniform pretension in the direction of actuation. For the antagonistically driven mechanism that requires two independent polymer sections a polymer sheet is stretched and a compliant electrode paste is placed on the top and bottom surfaces. Finally the top compliant electrode is partitioned in two sections. They are called electrode A and B of the top surface and the common electrode C of the bottom in Figure 3.2. In addition a mechanical output terminal is attached at the boundary of the partitioned electrodes. Although it is fabricated from a single elastomer film it works as the antagonistically driven actuator with partitioned electrodes so that it can provide bidirectional push-pull actuation. a Electrode A Electrode C Electrode B c b d Figure 3.3. Operation 54 H.R. Choi et al. In detail the device presented works as follows. Assuming that uniform pretensions are engaged tensions on both sides of the elastomer film are initially balanced. When the electrical input is applied to one of the elastomers it expands and the force equilibrium is broken. The output terminal therefore moves to rebalance the broken elastic equilibrium. For example as shown in Figure 3.3a if a positive input voltage is given on electrode A a negative one on B and a negative one on C then the output terminal moves toward electrode B because the elastomer on electrode A expands due to the input voltage on A. Similarly if a positive voltage input is given on electrode B while a negative input is applied to A and C then the output terminal moves toward electrode A. Besides the basic actuation the design presented can provide an additional feature