5
votes
Accepted
How can a coaxial stepper motor be used to drive the Z axis effector of a SCARA robot?
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
...
- 600
5
votes
What servos are suitable for a robot like Boston Dynamics’ Atlas?
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 ...
- 1,074
3
votes
Accepted
Does MIT Cheetah uses Series Elastic Actuator?
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 ...
- 1,074
3
votes
What are the pros and cons of Zip Chain Actuators in robotics?
The primary feature of a zip chain actuator is that it does not need extra depth to retract into. A standard linear actuator has a slider that will travel back behind the point of actuation. It will ...
- 25.4k
3
votes
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What is the typical intro example for control systems for a spherical joint?
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 ...
- 553
3
votes
Accepted
What is an "actuation state"
after reading this ... there are mentions of task-space, state-space, configuration-space, etc
https://www.researchgate.net/publication/...
- 600
3
votes
Accepted
Is it worth designing your own components to mount a ball screw?
The general answer I would give anyone, working on any project, who asked this question:
Should I buy commercially available, off-the-shelf (COTS) parts, or make my own?
would be to always buy off-...
- 15.9k
2
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How can I turn a bowl/glass upside down?
Here's an idea
Explanation
Instead of the servo bearing the weight, there is an axis through the bowl that the servo is attached to. This takes all of the strain off of the servo. The servo arm is ...
- 41
2
votes
Which motors are used in boston spot robot
I had the chance to play with Spot this afternoon and it is not hydraulic.
I bet for a stepper motor with cycloidal gears and position encoders. But I not really sure which kind of motor. They didn't ...
- 121
2
votes
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State of the art trajectory for fine precision robots
For very high-precision applications such as finishing, milling by CNC machines, jerk-bounded trajectories (that is, trajectories comprising polynomials of degree 3 of higher) are often used. If you ...
- 1,879
2
votes
Can't Read current on Pololu Dual MC33926 Motor Driver Shield for Arduino
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 ...
- 31
2
votes
Control method of large linear actuator
The LAS3 actuator draws a current of 2.5 Amps @ 24Volts and has a DC motor, so the H-Bridge in the link can be used to control it. It is even a bit overdimensioned. You can link the Ardunio to the H ...
- 6,682
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Design a robot that can apply hot glue to paper
The problem I see is that after a while of holding the trigger, you have to let go of the trigger and then squeeze again. This is because the trigger has advanced the stick of glue as far as the ...
- 207
2
votes
Accepted
Output power of an actuator - General definition
It reads to me like the author is stating that a stiffer material means it could make an actuator with more output power, which doesn't make a lot of sense to me.
Maybe they mean a more efficient ...
- 15.9k
2
votes
Controlling Actuated Robot Hand in Underactuated Manner
I don’t think underactuated is the proper term. You are trying to control multiple actuators with a single DOF. That is redundancy resolution. I have used the Simplex Method to compute stable ...
- 4,416
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votes
Accepted
Why Hydraulics and Not Motors?
Hydraulics and pneumatics let you separate the mechanical power generation component (compressor, hydraulic power unit, etc.) from the actuator. In the case of something like a robotic arm, this means ...
- 15.9k
2
votes
What type of actuators are needed for a high accuracy, low load weight robotic arm?
Ask yourself if you really need accuracy or precision. Because I think precision is easier to achieve than accuracy for most arms.
I am not sure I would be as worried about the actuator as the gear-...
Ben♦
- 5,885
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votes
Accepted
Controlling motion of single link
I believe all of the above is correct, but if someone thinks otherwise I would welcome the correction.
Yes, it's correct.
The boundary conditions now include (I think) $\ddot{\theta} = 0$ at $t=0$ ...
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1
vote
Accepted
Can you increase resolution/accuracy by mechanically averaging two actuators?
Your intuition is right, parallel mechanisms will improve precision, in general, when compared to serial mechanisms, but with a number of caveats:
Parallel mechanisms (as opposed to serial, chain ...
- 6,682
1
vote
How to determine actuator and process for PID, and how to intepret the output
I think you're way overthinking this.
If you want to evenly handle N events in a month, then you convert a month to whatever time granularity you like (T) and then handle (N/T) events per T.
For ...
- 15.9k
1
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What is the typical intro example for control systems for a spherical joint?
not a direct answer, but I would recommend you the following lessons by Peter Corke: robotacademy: joint control
- 189
1
vote
Calculate the inertia matrix of complex robotic mechanism
It is approximate and very accurate as long as the material properties are well defined. Many methods are combined to get it. Moment of inertia, parallel axes, mass distribution, etc etc. ...
- 497
1
vote
How to balance a long vertical bar
I believe your intuition about using push-pull linear actuators is in the right direction: you would have a quite hard time to control such a structure.
Traditionally, to deal with a cart-pole system ...
- 4,020
1
vote
What do the model numbers in Harmonic Drive gear drives represent?
It is the pitch diameter of the flex spline in inches/10. You can see it used it their equations for thrust force on the wave generator.
- 4,455
1
vote
Accepted
Potentiometer as pressure sensor in linear actuator?
Yes, you'll see the position become fairly stable when you've hit a rock (assuming that your bot is heavy enough to stall your actuator).
Measuring current will also tell you if you've stalled/are ...
- 146
1
vote
Are scissors what I want for moving straight up and out?
a robot that could get items out of the dishwasher and put them away
This is an active research topic. Toyota has a whole division working on assistive robotics, close to Stanford in Palo Alto. It is ...
- 720
1
vote
Accepted
Rotary Serial Elastic Actuator
For an arm with series elastic actuators I'm not aware of an open source design. There are many mechanisms you can find in research papers if you search for them.
For force control you have a few ...
- 4,455
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vote
Rotary Serial Elastic Actuator
There was a paper describing a rotary series elastic actuator for human-assistive systems in IEEE/ASME Transactions on Mechatronics, Vol. 17, No. 2 (April 2012).
The paper included diagrams of the ...
- 1,074
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vote
Replace screws with motors!
You are best off using the servo's horn/hub (the plastic or metal disk or arm that you attach to the servo), and screwing the arm to the hub. You get buy some larger horns for fairly cheap, and that ...
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