Fig 1.
Finite element model geometry, mesh design and boundary conditions of the PH artificial muscle consisting of four PH actuators.
The top end of the PH artificial muscle was fixed and a range of constant loads, F (0-18N), were applied at the bottom end. Linear triangular, linear mapped, and linear triangular-mapped hybrid elements were used to mesh the membrane, electrode, and liquid dielectric, respectively.
Table 1.
Material properties of the Peano-HASEL artificial muscle.
Fig 2.
Activation strategy investigation for the PH artificial muscle consisting of four actuators.
(a). The number of activated actuators was studied. One to four actuators were activated, corresponding to 25% to 100% activation level. (b). The number of activated actuators was studied. For 50% and 75% activation level, the middle and side actuators were activated in different combinations to study the effect of activation position. (c). For the activation signal, the profile, frequency, and phase of the signal were studied. Under 50% activation level, a step input and two ramp inputs were used to activate the actuators to study the effect of signal profile, sinusoidal signals with frequencies ranging from 0.5 Hz to 1000 Hz were used to activate the actuators to study the effect of signal frequency, a sinusoidal signal with a frequency of 40 Hz and a phase of 90 degrees and 0 degree were used to activate the actuators to study the influence of signal phase.
Fig 3.
Results obtained from the finite element model for number of activated actuators.
(a). Displacement-time response under no-load condition. (b). Force-length (i.e., maximum contractile strain under applied loads) relationship (c). Force-velocity relationship. (d). Three states of 25% activation level under no load conditions. Three states are the activated actuator starting to response, the actuator producing the peak strain output, and the actuator reaching a stable position. Colour legend represents the magnitude of displacement. The inside liquid dielectric is marked in pewter grey. (e). Three states of 50% activation level under no load conditions. (f). Three states of 75% activation level under no load conditions. (g). Three states of 100% activation level under no load conditions. Note that activation displacements shown in d-g are 1:1 scale.
Fig 4.
Results obtained from the finite element model for position of activated actuators at 50% activation level.
(a). Displacement-time response for three configurations under no-load condition. (b). Force-length (i.e., maximum contractile strain under applied loads) relationship (c). Force-velocity relationship. (d). Three states of the middle configuration under no load conditions. (e). Three states of the mix configuration under no load conditions. (f). Three states of the side configuration under no load conditions. Note that activation displacements shown in d-f are 1:1 scale.
Fig 5.
Results obtained from the finite element model for position of activated actuators at 75% activation level.
(a). Displacement-time response for two configurations under no-load condition. (b). Force-length (i.e., maximum contractile strain under applied loads) relationship (c). Force-velocity relationship. (d). Three states of the middle configuration under no load conditions. (e). Three states of the side configuration under no load conditions. Note that activation displacements shown in d-e are 1:1 scale.
Fig 6.
Results obtained from the finite element model for profile of activation signals at 50% activation level.
(a). Displacement-time response for three configurations under no-load condition. (b). Force-length (i.e., maximum contractile strain under applied loads) relationship (c). Force-velocity relationship. (d). Three states of the step input under no load conditions. (e). Three states of the steep ramp input under no load conditions. (f). Three states of the shallow ramp input under no load conditions. Note that activation displacements shown in d-f are 1:1 scale.
Fig 7.
Results obtained from the finite element model for frequency of activation signals at 50% activation level.
(a). Displacement-time response for four configurations (i.e., 5 Hz, 40 Hz, 200 Hz, and 1000 Hz) under no-load condition. (b). Displacement-time response for three configurations (i.e., 0.5 Hz, 1 Hz, and 2 Hz) under no-load condition. (c). Displacement-activation frequency relationship. Dynamic and quasi-static components of the total displacement were considered. (d). Force-length (i.e., maximum contractile strain under applied loads) relationship. (e). Force-velocity relationship. (f). Two states of the 1 Hz sinusoidal input under no load conditions. (g). Two states of the 40 Hz sinusoidal input under no load conditions. (h). Two states of the 1000 Hz sinusoidal input under no load conditions. Note that activation displacements shown in f-h are 1:1 scale.
Fig 8.
Results obtained from the finite element model for phase of activation signals at 50% activation level.
(a). Displacement-time response for three configurations under no-load condition. (b). Force-length (i.e., maximum contractile strain under applied loads) relationship (c). Force-velocity relationship. (d). Two states of the 40 Hz sinusoidal input with a phase of 0 degree under no load conditions. (e). Two states of the 40 Hz sinusoidal input with a phase of 90 degree under no load conditions. Note that activation displacements shown in d-e are 1:1 scale.
Table 2.
Activation strategies for the Peano-HASEL artificial muscle.