7
As others have said in comments, a screw is probably your best bet. It's mechanically pretty simple to set up, and could be made to look fairly tidy, which is always nice in a home.
But the main problem, as always is going to be doing this on the cheap. The cost of the parts soon adds up. Even if your motors are only $15, you still need to buy the lead ...
6
In short, what you are trying to do is well beyond the capabilities of top robotics research labs.
That said, here is a short list of general areas you need to look into:
Robotic arm dynamics (to swing the racket)
Vision processing to track the shuttle
Shuttle dynamics to predict shuttle path (this is not well studying so you would most likely have to ...
6
Actuators that use a worm gear can't generally be back-driven; these are the same gearing mechanisms that let you twist a guitar string to tune it without the tension being able to back-drive (and thus un-tune) the tuning mechanism.
Worm gears are nice in that they offer generally pretty huge reductions in speed, with a huge increase in torque. This leads ...
5
When selecting an actuator, you need to consider not just the force but also the power.
Power = force x speed
The faster you need to lift the lever, the more power you'll need. Companies like Maxon provide detailed graphs showing exactly how much torque you can expect at various speeds for their motors. Other companies may just state the motor's wattage.
...
5
The device you are looking for is a "pan-tilt" unit. They are typically used for pointing security cameras. If you find a "PTZ", i.e. pan-tilt-zoom security camera used, you could butcher it an just use the Pan/Tilt part.
5
With a series of planetary gear sets aligned axially, one can gear down by high ratios. For example, the picture below (a wikipedia commons image used in the planetary gear article) shows a 2.5-cm gearset with ratio -5/352, about 1:70. Stacking three of these would give a ratio of about 1:343000. Some torque and power would be lost to friction, and ...
5
To answer your questions about the motors/gearing:
To lift 5Kg at 1 metre distance - the "shoulder" torque needs to be 500 Kg.cm or about 5000 N.cm.
This is far above the torque of most model servos, so forget them; robots of this sort of performance generally use a specialist motor, much more than 12V and a purpose built gearing arrangement that probably ...
5
Series elastic actuators tend to have more stable force control because the spring filters out the high-frequency motion of the mechanism. A low frequency in the system dynamics means that you can use slower control techniques, which is important when using digital controllers with naive control implementations, and sensors with significant abbe error and ...
5
i found out that it is called an RZ tool ... google scara RZ tool
there is a captive rotating "nut" on the threaded shaft that causes the shaft to move linearly
there is a spline (raceway) in the screw shaft to prevent turning
the picture that you posted probably uses a ball screw/spine like this one ... https://tech.thk.com/upload/catalog_claim/pdf/...
4
Well, being the manipulator removable, so you can attach other thing to the valve shaft, you have so much options.
Mechanical coupling
You could use a coupled rotary actuator to the shaft by the means of a shaft coupler. There's many types, this is a simple one, but you probably would not get the actuator axle full aligned with the valve shaft, so a coupler ...
4
When there is miscommunications between the microcontroller and a chip, assuming the electronics are not damaged, there could be a couple of things that can go wrong. Of course, further diagnosis is required. Typical things that could go wrong are (generally, not just in your particular case):
Connections: Is the chip connected to the correct power supply? ...
4
Regarding point 1, yes you are understanding the problem correctly.
Regarding points 1 and 2, I believe what you are looking for is the Nyquist-Shannon sampling theory. This theory says that your sampling frequency should be greater than 2x your "highest frequency of interest". This is to prevent aliasing, where you can incorrectly measure a high-...
4
Actuation is a complex subject that cannot be reduces to 1 component alone. It is the interaction of software electronics and mechanics. "Toy" servos tend to incorporate everything in one small package. Industrial robots have 3 or 4 separate components (each costing several hundred or a few thousand euros) instead.
To answer your question, worm gears are ...
4
The Boston Dynamics’ Atlas robot doesn't actually use servo motors. It uses electrically-powered hydraulic actuation.
I saw a presentation by Boston Dynamics' Marc Raibert where (if I remember correctly) he said they used to use Moog actuators designed for the aerospace industry, but that they were now using a motor that they build in-house that is ...
3
Vacuum gripper - I think. Perhaps something like the lynxmotion version, which generates the vacuum with a motorised syringe:
http://www.lynxmotion.com/p-788-vacuum-gripper-kit.aspx
Alternatively - a flat electrostatic gripper can be used for paper handling but it involves a high voltage on one side of a plate, covered by a thin plastic sheet. A bit of ...
3
First
I would like to caution your choice of motor torque. I don't know how you generated the drawing of your wrist, but CAD packages like Inventor or Solidworks can easily generate masses and moments of inertia if you select the correct material.
For looking solely at holding torque, the torque required to not move, you need a torque that supports the ...
3
Actuators Forces
Do I get this right: you have a theoretical model of a rigid multibody system and would like to perform rigid body dynamics computations. You have implemented the model and now would like to compute how the model behaves when driven by an actuator.
However what is an actuator for you? Is it simply a force acting at that joint? Is it a DC ...
3
This design is definitely plausible, but there are some problems I can see.
The maximum length is defined by the force the magnets can lift, since the ones lowest in the stack won't push the other ones up after some amount of them.
The magnets will want to get as far from the force as possible, so they will most definitely not go straight up. This calls for ...
3
I always add 100-120% overhead (normally this just means the next bigger unit than exactly what I need) but also this comes with experience, a motor that can just barely lift your load will do so very slowly.
3
There are two more factors to consider: Complexity and cost.
Industrial robotic arm like that
industrial robotic arm http://halcyondrives.com/images/robotic_arm.png
Image from http://halcyondrives.com
normally use torque from the gearbox to direct drive the joint, now think about the torque the gear reduction should support and the size/weight it will be? ...
3
Like jwpat said, I think the only package you'll find for what you're looking for is active suspension, but good luck getting official support from the manufacturer unless you have some automotive OEM sponsorship.
Note that jwpat linked to adaptive suspension parts, which vary damping as mentioned, not active suspension, which uses an actuator to do things ...
3
I have worked on a cartesian robot with similar requirements† as your own, and we selected direct drive synchronous linear motors for our x/y stages. In our case, both axes were around 2m in length, but magnet the tracks have the potential to be as long as you need to build them.
† Less than an order of magnitude higher at $2/5ms^{-1}$ ...
3
what metal should I use?
Copper wire works better than nichrome wire, according to
Homemade Artificial Muscles IV.
That says
Nichrome is used in places like your toaster mainly because it can get
very hot without melting or oxidizing. But I don't need or want the
heating elements in my artificial muscles to be red-hot. I would like
to be able to ...
3
A robot like the one you refer to probably has a mix of transmission types that increase in power-to-weight ratio and decrease in size and stiffness as you move outwards on the kinematic chain. The base joints likely have planetary or cycloidal gearing, with maybe some spur gears in the middle, and maybe a harmonic drive reducer at the end effector. I don't ...
3
It seems that the answer is that it doesn't actually use either of those designs.
According to the paper Proprioceptive Actuator Design in the MIT Cheetah: Impact Mitigation and High-Bandwidth Physical Interaction for Dynamic Legged Robots by Patrick M. Wensing et al, the MIT Cheetah robot actually uses a proprioceptive force-control actuator Design.
The ...
3
The best example I can think of would be the spherical pendulum. Albeit, this is not exactly the easiest thing to regulate as you have two degrees of freedom and a frictionless contact (well depending on your design)
Here is a youtube of such an example of a method to control it.
You'll often read that the Equation of motion will be described through ...
2
I know this thread is old but it's high on Google results and I would like to clarify for anyone who stumbles upon it in the future an answer not yet listed: this chip is not designed to read current accurately below 0.3A and only gives 20% accuracy above that. This is not listed in the board spec sheet but rather the chip spec sheet. If you're running ...
2
I think dielectric mechanism like piezo are suitable for compact designs.
These might be usefull
http://en.wikipedia.org/wiki/Piezoelectric_motor
https://www.google.com/patents/US4812698
2
If you haven't come across the Rigid Body Dynamics Library (RBDL) you might want to look at how they implement it, and/or contact the author Martin Felis.
2
A machinedesign.com article, “Exclusive interview: Gill Pratt on how compliant actuators revolutionized robotics”, includes a close-up picture of an SEA (series elastic actuator) mechanism developed by a robotics research group at Vrije in Brussels, and a picture of a Baxter arm, captioned “In the larger red circle is one of Baxter's many compliant ...
answered Apr 27 '15 at 15:43
James Waldby - jwpat7
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