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 ...
HighVoltage's user avatar
  • 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 ...
markshancock's user avatar
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 ...
Mark Booth's user avatar
  • 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 ...
50k4's user avatar
  • 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 ($x$,$y$,$z$...
hauptmech's user avatar
  • 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 ...
Max Witter's user avatar
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 ...
SteveO's user avatar
  • 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 ...
Akshay Kumar's user avatar
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 (...
Victor Jaramillo's user avatar
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 ...
Diego C Nascimento's user avatar
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's user avatar
  • 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 ...
Greenonline's user avatar
  • 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 ...
Pete Kirkham's user avatar
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, ...
Mark Booth's user avatar
  • 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 ...
Wolly's user avatar
  • 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 ...
Chuck's user avatar
  • 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 ...
Ugo Pattacini's user avatar
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 ...
DrMrstheMonarch's user avatar
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 ...
user241585's user avatar
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 ...
James Waldby - jwpat7's user avatar
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 ...
Andy's user avatar
  • 1,031
2 votes

I want my stepper motor to switch speed while traveling (not acceleration wise)

...
gerd's user avatar
  • 21
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"...
Ian's user avatar
  • 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 ...
Ryan Loggerythm's user avatar
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 ...
Brian Lynch's user avatar
  • 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 ...
Mark's user avatar
  • 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 ...
Pete Kirkham's user avatar
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 ...
gilhad's user avatar
  • 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 &...
TimWescott's user avatar
  • 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://...
JCDeen's user avatar
  • 186

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