12
votes
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Can RC servo motors continually rotate?
In a nutshell, servo motors and stepper motors are not technically the same things. The link you posted is only for servos and not stepper motors. A servo motor assembly does not rotate freely like a ...
- 1,091
7
votes
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Using brushless motors for very high torque
Your expectations are rather aggressive for a DC motor.
First - 40Nm (350in-lbs) is A LOT of torque! Ex: A max rated torque for 1/4-20 bolt is only 75 in-lb (8.5Nm).
Second - The mechanical power ...
- 705
6
votes
Can RC servo motors continually rotate?
Whether a motor can spin continuously depends how is is constrained by other parts of the system.
An rc servo like the MG995 will typically have a motor, a gearbox and a limited travel potentiometer ...
- 4,098
6
votes
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Passing power through a motor
It is called a slip ring.
It works the same as a brushed motor.
See here for a robotic oriented one.
Larger versions handle power, and cost more.
Also near field technologies such as those used to ...
- 2,013
5
votes
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What is the required theory behind building a robotic arm?
There are 2 (or 3, depending on how the planned lifetime of the robot is) thing thats you have to consider.
Static load:
The motors stall (zero revolution) torques have to be able to hold the weight ...
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5
votes
Struggling to understand Jacobian Inverse Kinematics
You will find it helpful to keep the physical robot and the math separate.
The kinematics equations map joint parameters (which are often grouped as a vector $q$) to Cartesian coordinates ($x$,$y$,$z$...
- 4,235
4
votes
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Rotate (and stop) a large disk in very tiny increments
You can use stepper motors easily:
Given the 20cm diameter, this is around 63cm circumfence. Your target stepsize is around 0,1mm. This means the motor should do around 6300 steps per revolution.
If ...
- 1,647
4
votes
How to detect when a stepper motor has stalled?
I found that the FFT of the current waveform of the stepper often shows the natural frequency harmonics of the motor+driver system AND that during a stall extra frequency harmonics appear!!! all you ...
- 41
4
votes
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Choosing stepper motor for hand
I have used MicroMo's stepper motors in the past. You can find their information here: http://www.micromo.com/products/stepper-motors/stepper-motors-datasheets
However, I don't know if a design ...
- 4,326
4
votes
What are the equations of a s-curve position path?
The S-Curve profile can have several divisions along the time axis
7 divisions as per this image. This example has a constant positive jerk zone, a constant acceleration zone, a constant negative ...
- 661
4
votes
Accepted
How can I draw a line using rotation of two circles?
Made a quick diagram and a couple of calculations in matlab, let me know if it works for you.
First of all, I am assuming you are considering your piece of paper as your reference coordinate system (...
- 104
3
votes
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What is required to build a simple XY-stage?
Simple X-Y stages are well understood and form the basis for the many open source hardware projects for 3D printers.
Each axis of an XY stage can be made from a pair of 6mm stainless steel rods, ...
- 4,098
3
votes
How to detect when a stepper motor has stalled?
You need to quantify : "I measured the current through (one of the 4 wires of) my stepper motor, and it's always within a few percent of 0.5 A". A 'few percent' may be all you need to detect a little ...
- 31
3
votes
How can I increase the resolution of a PWM signal?
You won't ever get 'exactly' 2042.8878 RPM, so going with your measurement accuracy I will assume you mean 2042.8878 +/- 0.0005 RPM. This is approximately an error of 1 part in 4 million. So let's ...
- 501
3
votes
RC car circuit: what does it do?
At a guess this is either a Hall Effect, or Optical, speed and direction measurement device. The five wires will be GND, and outputs of Sensor1 and Sensor 2, and the other two would be the power ...
- 1,284
3
votes
Which kind of motors and how powerfull should they be for a robotic arm
This type of question "how much torque does my robot arm need" has been answered many times on this site:
Simple equation to calculate needed motor torque
Design and construction of universal robotic ...
Ben♦
- 5,215
3
votes
Accepted
2DOF arm with quick movement: Stepper, servo, or DC motor?
Servo mechanisms are not the "popular" RC-Servos (not-only). Servo is a closed-loop control, not only for motors. Even Steppers could or not be servo-motors. RC-servos are in major cases a DC brushed ...
3
votes
Accepted
Will this have more or less lifting strength
Every action has an equal and opposite reaction. Each motor/joint in a linear chain of actuators (snake) needs to be capable of supplying the appropriate reaction forces.
This mean that, if you have ...
- 14.7k
3
votes
Accepted
What are the equations of a s-curve position path?
To come up with a mathematical expression of the position reference $x\left(t\right)$ as a function of time $t$, we can inspect the profile of the acceleration $a\left(t\right)$. It is piece-wise ...
- 3,575
3
votes
Accepted
Specification calculation for choosing a proper stepper motor for Ball Lead / Screw system
When looking for motors, you usually are trying to figure out specific things with specific requirements.
Holding Torque
Torque at Speed
Resolution (for steppers)
NEMA size
Positional Accuracy vs ...
- 478
2
votes
Why does microstepping give less torque?
The reason for this is that when attempting to hold a position between positions, you are not only fighting the torque from your load but that generated by the magnets in your stepper more info here
- 1,909
2
votes
Current-limiting stepper motors for RepRap
I'm using a NEMA23 on my Y axis on my greatly frankensteined MendelMax. The bed was elongated to 350mm along with other upgrades, so I needed the bigger motor. It's running nice and cool at 26 volts ...
- 161
2
votes
Rotate (and stop) a large disk in very tiny increments
Why do you need to have the motor at the axis? Wouldn't it be much easier to have several at least one motors at the edge of the disc and the disc would lie on wheels (the smaller the more accurate)? ...
- 146
2
votes
Accepted
How does Fliike Smiirl counter mechanism work
As far as I can tell, you are asking how a "split-flap display" on things like the
Flapit, the Smiirl Fliike, etc. works.
flip clocks
Some flip clocks -- "Retro Flip Clock", etc. -- use a single ...
- 4,385
2
votes
How to know what type of stepper motors to use when designing a robot
Math is the short answer. You need to figure out what you want the motor to do, i.e. how much it needs to lift, amount of torque etc. You also need to consider how it is going to be powered. If its ...
- 157
2
votes
Passing power through a motor
The device you are looking for is broadly known as a slip ring, but since you are trying to power other motors through it you should be aware that a slip ring is not electrically identical to a wire. ...
- 10.8k
2
votes
Building industrial-like robotic arm
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 ...
- 1,956
2
votes
Building industrial-like robotic arm
A series elastic actuator is really just a motor/gearbox with passive compliance built in (hence the spring). A google search finds http://ihmc.us/groups/sea/ (with links to some specs and ...
- 1,021
2
votes
Crock Pot Knob Turner
You might be better served by using a PID "profile controller" -- it would be easier (cheaper) and more accurate than trying to manually control the knob. These are also called "Ramp/Soak controllers"...
- 10.8k
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