Soft Hybrid Actuator

Vince Chong Author

04/01/2021 Added

11 Plays

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Combination of two soft actuators to yield a higher performance soft actuators with its bistable state

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[00:00:01.130]Hi, my name is Jun Hong Vince Chong
[00:00:03.340]and my advisor is Dr. Eric Markvicka
[00:00:05.960]and I'll be talking about a soft hybrid actuator
[00:00:08.390]that I've been researching for the past one year.
[00:00:13.450]So as we know the current technology
[00:00:15.200]uses pneumatic or hydraulic system
[00:00:17.090]that requires a rigid and heavy component
[00:00:19.000]that are tethered to a pump, compressor,
[00:00:20.793]valve and et cetera.
[00:00:22.711]The article at the right
[00:00:23.840]shows that it uses a two actuation system
[00:00:26.142]which are a pneumatic system and mechanical system
[00:00:28.730]to create a bi-stable state leading to a faster actuation.
[00:00:34.180]And because of the article on the right,
[00:00:36.120]we have been inspired to use the same concept
[00:00:39.300]where we combined two soft actuator
[00:00:41.010]into a hybrid soft actuator
[00:00:42.729]to yield a higher performance self actuator
[00:00:44.880]with its bi-stable system
[00:00:46.730]with the usage of electricity, which are untethered.
[00:00:49.960]And the candidate chosen for this research
[00:00:51.690]are the SMA and the LCE,
[00:00:53.320]where these two soft actuator
[00:00:55.070]has the ability to recall or return to its original state
[00:00:58.430]after actuating through the presence of heating element.
[00:01:03.110]And in order to meet this integration system,
[00:01:06.640]four grams of RM257
[00:01:09.650]is poured into the 13 millimeter vial.
[00:01:12.253]1.6 gram of toluene is poured into the vial
[00:01:14.160]to dissolve the RM257.
[00:01:16.800]And the solution is then poured into the oven
[00:01:19.290]at 80 degrees C for five minutes
[00:01:21.880]or until it dissolve completely.
[00:01:25.110]Then the solution is then cooled to room temperature
[00:01:28.170]and 0.217 grams of PETMP
[00:01:31.220]and 0.9157 grams of EDDET
[00:01:35.160]is then poured or added into the solution.
[00:01:39.740]Note that if the solution recrystallize,
[00:01:41.770]place the solution back into the oven at 80 degrees C.
[00:01:45.770]After that 0.0257 grams of HHMP
[00:01:49.720]is then dissolved into the solution.
[00:01:52.890]A separate solution of catalyst is then prepared
[00:01:56.020]by making a 1:50 ratio of DPA to toluene
[00:01:59.600]and pour it into the vial.
[00:02:02.290]Then 0.568 grams of catalyst
[00:02:05.930]is then poured into the solution
[00:02:08.870]and quickly mix it with a vortex mixer.
[00:02:12.640]After that the solution is then placed
[00:02:14.170]into the vacuum chamber for one minute
[00:02:16.200]at a pressure of 508mmHg.
[00:02:20.050]While the solution is within
[00:02:21.796]or inside the vacuum chamber,
[00:02:23.980]the negative mold is then created
[00:02:25.680]by using a microscopic slide of 25.4 millimeter width,
[00:02:29.378]76.2 millimeter length
[00:02:31.080]and 0.8 to 1 millimeter thickness.
[00:02:35.180]The SMA is then placed parallel to the length of the mold
[00:02:38.810]and the solution is then injected into the mold
[00:02:41.440]along with the SMA and the solution is then,
[00:02:44.060]and then the sample is then put into the fume hood
[00:02:46.470]for 12 hours in room temperature.
[00:02:50.580]After that the sample is then transferred
[00:02:52.240]into the vacuum oven at 80 degrees C,
[00:02:54.390]at pressure of 508mmHg for 24 hours.
[00:02:57.760]Which result in white, glossy and nonsticky,
[00:03:01.200]opaque appearance LCE
[00:03:03.058]with 25.4mm width,
[00:03:05.365]76.2mm length and about 2mm thickness.
[00:03:12.570]While doing this research,
[00:03:13.600]an interesting discovery has been made.
[00:03:17.040]Where the negative glass like mold
[00:03:19.940]is replaced with a silicon rubber
[00:03:21.900]which result in making a sticky LCE.
[00:03:24.460]While it still maintain its stimuli responsiveness
[00:03:28.070]and it has been suspected
[00:03:29.320]that the toluene melts the rubber from the silicone rubber
[00:03:31.930]and mix it with the LCE,
[00:03:34.266]creating an LCE that can be bind to any surface
[00:03:37.190]except for the silicon rubber under the room temperature.
[00:03:40.380]So the longer the curing time for the HHMP,
[00:03:43.850]the lesser the stickiness of the LCE temporary
[00:03:46.880]when exposed to UV light.
[00:03:48.710]On the other hand,
[00:03:49.620]the longer the LCE in cold temperature environment,
[00:03:53.230]the lesser the stickiness of the LCE temporary.
[00:03:59.610]So the summary of its mechanical property
[00:04:02.160]it can be done by using a heat gun.
[00:04:05.510]Which result in the trade off
[00:04:06.690]between the SMA and a LCE combination.
[00:04:10.350]The SMA alone actuate faster than the LCE alone
[00:04:13.470]but the SMA alone withstand lesser weight
[00:04:15.610]compared to the LCE alone.
[00:04:17.960]So increase in thickness of LCE only will increase the time
[00:04:22.050]to withstand the weight at its fully contracted state
[00:04:25.200]and also holds heavier weight.
[00:04:27.320]But it will increase the time to actuate
[00:04:30.420]in contrast to an increase in the number of integrated SMA.
[00:04:36.200]So having an integrated SMA
[00:04:37.920]provide the LCE with weakness,
[00:04:40.370]creating a backbone where it is likely to crack
[00:04:42.750]near the interface of the LCE and the end of the SMA
[00:04:46.630]since the LCE is soft unlike the SMA which is hard.
[00:04:50.670]The LCE is also likely to form a crack
[00:04:52.870]if a significant uneven heating is provided
[00:04:55.110]where the sample has two or more SMA
[00:04:58.620]integrated into the LCE.
[00:05:01.010]Additionally, crack is also formed
[00:05:03.198]at the end of the shorter end of the spring
[00:05:05.290]compared to the longer spring.
[00:05:12.220]Next is a summary of result of 50 grams actuation
[00:05:15.030]which is done by using electricity
[00:05:18.030]which is clamped at the both end of the spring.
[00:05:21.410]So the output current is kept at 1.3A
[00:05:24.640]with different capacitor and voltage
[00:05:26.340]since current is the only factor
[00:05:28.710]that controls the actuation of the spring.
[00:05:31.920]Which result in the SMA only
[00:05:34.030]being the fastest in contracting
[00:05:35.700]followed by two and then one SMA integrated LCE.
[00:05:40.000]Note that this is not a bi-stable system
[00:05:42.970]since no HHMP is integrated
[00:05:46.300]and this is because due to the issue arise.
[00:05:51.110]Because of the LCE is an insulator,
[00:05:53.260]the integration of the SMA into the LCE
[00:05:55.520]will be slower than SMA itself.
[00:05:58.240]By that, longer time are needed
[00:06:00.270]to spread the heat through the LCE
[00:06:02.140]to actuate along with the SMA.
[00:06:04.890]The HHMP which is a self actuation by tension,
[00:06:08.420]integrated into the LCE with SMA
[00:06:11.100]makes a bi-stable system.
[00:06:13.150]If curing of HHMP is too long,
[00:06:15.640]higher power or time are needed
[00:06:17.370]to overcome the tension on the HHMP
[00:06:19.050]integrated within the LCE
[00:06:20.636]or even degrade the actuation behavior of the LCE.
[00:06:24.170]If curing of HHMP is two short,
[00:06:26.300]higher tension of the HHMP is needed
[00:06:28.270]to overcome the compressive forces of the SMA.
[00:06:31.690]Next is a programming issue with the SMA.
[00:06:34.720]The maximum current of the SMA is kept at about 1.3A
[00:06:38.030]which is known by doing trial and error
[00:06:40.020]regardless of voltage.
[00:06:42.010]Current is the parameter
[00:06:43.540]that controls the actuation of the SMA.
[00:06:46.740]By that, if the current is too high,
[00:06:48.860]the SMA will reprogram itself
[00:06:50.490]and deviates from its known actuation behavior.
[00:06:53.140]Just like in this video
[00:06:54.720]where it's not supposed to elongate
[00:06:56.520]in the absence of a heating element.
[00:07:00.400]So the future direction and the potential
[00:07:02.260]of this research can show us that,
[00:07:03.550]if the conductive liquid metal, EGain,
[00:07:05.280]is integrated in the LCE along with the SMA,
[00:07:08.160]allowing heat to spreads faster throughout the LCE,
[00:07:11.030]it can potentially to be faster and stronger
[00:07:13.190]than having just an LCE or SMA actuation.
[00:07:15.884]And potentially overcome the tension of the HHMP,
[00:07:19.460]allowing having a faster bi-stable system
[00:07:21.430]leading to faster actuation.
[00:07:23.150]Here so have a potential to create a BiLCE,
[00:07:26.391]analogous to bimetallic strip
[00:07:28.020]by using our polyamide heater
[00:07:29.510]and potentially conductive liquid metal
[00:07:31.320]and thermoelectric Peltier cooler pad.
[00:07:33.550]Which generate a whole new fast bi-stable system
[00:07:36.160]that is both potentially efficient
[00:07:38.020]to move in land and water
[00:07:39.990]and have an integrator
[00:07:41.150]while being, safe fast gripper action, as well.
[00:07:43.700]As this series of picture shows.
[00:07:47.670]And here are the citation and reference
[00:07:50.190]and acknowledgement support
[00:07:51.380]from the UCARE,
[00:07:52.320]there is NASA Nebraska Space Grant
[00:07:54.190]and then Nebraska Tobacco Settlement
[00:07:55.950]Biomedical Research Development.
[00:07:57.970]And thank you for listening to my presentation.

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Soft Hybrid Actuator

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