gene-h

21 ms·

151.
by gene-h 6y ago
And now optical navigation has been flight proven so it can be used on other missions.
152.
by gene-h 6y ago
Boston Dynamics probably does some form of force control. That is controlling the force applied to the ground by the legs in addition to just the position the leg is moving. The actuators here appear to be purely position controlled.
153.
by gene-h 6y ago
It is quite difficult to control with the mouse. It's basically impossible to kill rotation or velocity along a given axis. So one ends up with bang-bang control, constantly oscillating around the target. I am also somewhat horrified t
154.
by gene-h 7y ago
Using 60 GHz for communication at these distances is pretty strange because 60 GHz is strongly attenuated by the atmosphere. Not only that, but atmospheric attenuation peaks at 60 GHz because that's what oxygen absorbs[0]. Some militar
155.
by gene-h 7y ago
I wouldn't say that robotic manipulation in unstructured environments is exactly stuck, just progressing very slowly. There has been some progress since the DARPA Humanoid Challenge and Manipulation Challenge. Robots seem to be getting
156.
by gene-h 7y ago
The servo they use is $493[0], at that price I wouldn't necessarily consider it a hobby servo. The control for that specific series elastic servo needs some work. There have been other attempts at making cheap series elastic actuators.
157.
by gene-h 7y ago
It's unfortunate that we still don't have cheap torque controlled robot actuators. Controlling force rather than position led to a drastic improvement in walking robots. I would also highly recommend using something beefier than a
158.
by gene-h 7y ago
It doesn't seem like they've made much progress since this snopes article came out in 2017[0]. I'm also skeptical that they could use these batteries to practically power a cellphone. So a cellphone requires about an average
159.
by gene-h 7y ago
The single digit efficiency metric is probably overall conversion efficiency of sunlight. The two efficiencies are probably quantum yield, or the efficiency at converting one wavelength of light. We have two because the molecule's tris
160.
by gene-h 7y ago
So this work seems to be about demonstrating the engineering aspects of molecular solar thermal energy storage. They put all this work into describing the microfluidic chip they use, pumps, and other details. They also use an azobenzene der
161.
by gene-h 7y ago
Disappointingly this article doesn't provide a link to the research. I think this paper might be it[0], but I am not sure. So in the paper they develop a material that has an estimated storage efficiency of 3.8%(this might be solar con
162.
by gene-h 7y ago
Ideally, you'd mandate wireless usage at 60 GHz. 60 GHz is strongly attenuated by oxygen in the air[0]. In fact some military satellites use it for secure communication between satellites because it's strongly attenuated by the at
163.
by gene-h 7y ago
Venus' lower atmosphere is actually composed of supercritical CO2 at 90 atm and ~450°C which makes corrosion interesting[0]. sCO2's property of acting like a solvent works against us in this case. Copper grows a hair copper sulphi
164.
by gene-h 7y ago
Fluidics can work much faster upto 10 KHz[0], maybe even up to 30 KHz or higher if one uses light gases like hydrogen or helium. Although fluidic elements tend to be pretty and have a foot print on the order about a square centimeter. They
165.
by gene-h 7y ago
Univac built a 4 bit computer that ran off of compressed air using fluidics[0]. Making a TV would be much more difficult though. It is very difficult to make mechanical systems that can interact with electromagnetic radiation or work at sim
166.
by gene-h 7y ago
Even if the satellites are perfectly black they'll still interfere with radio astronomy. Even if they don't transmit they will interfere with radio astronomy because they're warmer than the vacuum of space and will emit black
167.
by gene-h 7y ago
I'm skeptical that a stepper motor would be able to support it's own weight and more without a gearbox. This is especially important for making serial manipulators. Also keep in mind that what they're aiming for here is repea
168.
by gene-h 7y ago
The main cost is the actuators. The servos they use are the only ones out there with integrated feed back from the sensors which is required so they can calculate hardware safety. They also have, albeit pretty bad, torque control which is n
169.
by gene-h 7y ago
TL;DR we can stretch a really long piece of fishing line from the Moon's surface to geostationary orbit. And we can probably send payloads to the moon by docking with said cable in geostationary orbit too. The funny thing is I literall
170.
by gene-h 7y ago
The Venera landers stopped functioning because the solder in their circuits melted. Higher temperature solder could have been used preventing this problem, but the key issue is that silicon no longer functions as a semiconductor at these te
171.
by gene-h 7y ago
This isn't that new, Yamaha has been selling a remotely controlled helicopter specifically made for applying insectcide on crops since 1991[0]. They were even used in aerial robotics research for a bit[1]. Helicopters are particularly
172.
by gene-h 7y ago
I wonder if they had a problem with the nuclear powered cruise missile they are developing[0]. It's interesting that they are recommending taking iodine pills though, because that might imply a release of radioactive iodine, a fission
173.
by gene-h 7y ago
I don't think it's that disruptive. One thing that the 2009 roadmap for additive manufacturing has emphasized is the need to move from point to line and area deposition[0]. This still scans a point like stereolithography has done
174.
by gene-h 7y ago
And unfortunately, their operation is thermally based. This means they are inherently inefficient and as you scale up fine control becomes more difficult due to increased thermal mass.
175.
by gene-h 7y ago
Spacecraft transmit power and antenna size is limited. This means the amount of power that arrives at earth is rather low because microwaves spread out quite a bit with distance. The other issue is that NASA only has so many big radio dishe
176.
by gene-h 7y ago
There might be some scientific value for taking video. One measurement where video might be valuable is measuring the saltation threshold, or the wind speed at which grains begin to move, of the surface using rotor downwash. These measureme
177.
by gene-h 7y ago
Interestingly they actually exploit these cold temperatures to keep things cool. The Dragonfly Gamma-Ray and Neutron Spectrometer(DraGNS)'s gamma ray detector is mounted outside.[0] In most other probes the detector would need to kept
178.
by gene-h 7y ago
it's all fuel, but there's no oxidizer
179.
by gene-h 7y ago
We have solar cells which have exceeded the Shockley-Queisser limit. It's possible to exceed the Shockley-Queisser limit by having a multiple junction solar cell. In fact the world record for conversion of sunlight is 46%[0]. Of course
180.
by gene-h 7y ago
I don't exactly understand what the author means by open sourcing graphene. If they mean putting the methods used to produce and do things with graphene out there in the open, scientific journals are for the most part already doing thi

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