As a proof of concept, we applied voltage to the diaphragm actuators in the robot prototype one at a time to see if deforming one diaphragm while keeping the other one relatively taut would displace the heavy, lump of mass suspended between the diaphragms and hence, destabilize the sphere and cause it to move and resettle at a equilibrium.
Device Performance contains a video of our experiment which shows the prototype rocking back and forth in response to electrical input.
Factors Limiting Device Performance lists some of the limitations in our prototype that might have prevented it from having better performance or larger displacement for a given input.
Device Performance
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Factors Limiting Device Performance
- The cardboard actuator frames were rather heavy. Consequently, the overall mass of the robot was not very well concentrated at the center, which is the part being displaced by the rigid beams and diaphragms.
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External wiring of the robot impeded the robot's ability to roll freely when disturbed
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Since the components of the robot were assembled by hand, it was very difficult to ensure symmetry of the placement and adhesion of parts.
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We could not find a suitable material that is dense enough and of regular, symmetrical geometry to hang upon the rigid beam so we made do with brass padlocks and secured those in place with scotch tape and hand-molded Plasticine. Again, this influenced symmetry of the robot and added bulk to the mass (which we wanted to be concentrated).
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Uneven surface of the plastic hollow sphere meant that the sphere's tendency to roll in any direction when disturbed is not completely unbiased
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The dielectric elastomer films were stretched by hand and the compliant electrodes were hand-brushed. Inevitably, there would be irregularities and lack of symmetry. As a result, the maxwell stress induced in one diaphragm was larger than the other given the same input voltage.