12
votes
Accepted
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 ...
- 1,086
7
votes
Accepted
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 ...
- 4,213
5
votes
Accepted
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 ...
- 6,612
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 ($x$,$y$,$z$...
- 4,335
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
Accepted
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 ...
- 4,376
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 ...
- 671
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 (...
- 114
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
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♦
- 5,780
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 ...
- 1,342
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 ...
- 521
3
votes
Accepted
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, ...
- 4,213
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
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 ...
- 15.8k
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 ...
- 3,985
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 ...
- 518
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
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 ...
- 1,981
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 ...
- 1,031
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"...
- 11k
2
votes
How to make a stepper motor rotate and come to a position of certain degrees (say for 90 degrees) from any initial position?
You're in luck. Stepper motors do not have absolute positions. There is no 0-degree mark, nor 90-degree mark, etc. Everything is relative to the current step, so you don't have to query where the ...
- 275
2
votes
What is the required theory behind building a robotic arm?
It sounds like you are developing a robotic manipulator from scratch so I also assume you will be writing software for position control too. Both the design and control depend on not only the dynamics ...
- 1,377
2
votes
How to find Friction or Viscous force b (nmsec) in DC motor
When no other load is on the motor, any torque that the motor is producing is to overcome the friction. If you know how to calculate your friction from the torque needed to overcome it (I don't), then ...
- 331
2
votes
Accepted
What is the best way to plug in more than 3 stepper motors into a Arduino Uno board?
Each EasyDriver takes two digital inputs - step and direction. These do not need any particular protocol so you can use any pin capable of digital output.
The Arduino uno has 14 digital outputs and ...
- 521
2
votes
Why are some motor shafts stiff while others spin freely when not powered?
IMHO it depends on two factors:
if there is gear on the servo (so to motor rotates fast, the result is slow precise motion with high force), then moving it manually even little means to rotate the ...
- 453
2
votes
How to reduce the small free rotation/movement of a stepper motor shaft?
It's a geared stepper, which means that it's a stepper (64 steps, I gather) followed by a 64:1 (approximately) gearbox. What you're seeing is almost certainly backlash in the gear train (see where I &...
- 1,891
2
votes
How to reduce the small free rotation/movement of a stepper motor shaft?
Adding a worm gear to connect the output shaft to the load you are trying to move might solve your problem, since worm gear arrangements are "self locking".
Here is a reference for you: http://...
- 186
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