# Tag Info

12

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 DC motor. The rotation angles are usually limited, and every servo has a "lock" position where it stays by default. A positive pulse makes it move clockwise, ...

7

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 of a motor results from RPM*Torque. 40Nm*100rpm is 0.56hp (420W at 100% efficiency). That is A LOT, about 1/2 of what today's high end cordless drills can do. ...

6

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 wirelessly charge your electric toothbrush, and more recent wireless cell phone chargers, are potential solutions

6

The short answer is yes, but the long answer is that you're approaching the code the wrong way and will need to rewrite things a bit. It looks like you're attempting to read a button and have it flash some LEDs while at the same time having your stepper move back and forth. The problem is your delay(5); commands, which pause the execution of your code. ...

6

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 to provide position feedback. It is this final component which prevents the rc-servo from rotating continuously. In the case of the MG995, it can apparently be ...

5

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 in the robots most unfavorable pose (usually the arm stretched out). You can determine this by static modelling, that involves only an equilibrium of forces for ...

5

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 ($x$,$y$,$z$). If you take the first-order partial derivative of the kinematics equations, you get a set of equations that map a change in the joint parameters to a ...

4

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 you take a common stepper motor, which has a step size of around 1,8° per step. So the motor performs 200steps/per revolution. your target is 6300. Now we know ...

4

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 need is a fast, bidirectional current to voltage conversion IC and a narrow band pass filter to detect if the extra harmonics are present.

4

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 process of "make decisions then see what fits" is the best approach. You should determine the performance you need, then look for components, and base your ...

4

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 jerk zone, a zero acceleration zone and then the vice-versa. This is the S-Curve in its most general form 5 divisions if there exists no constant acceleration ...

4

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 (CS), in the sense that the coordinates $(x_2, y_2)$, are the input to your problem. Also, I will consider $\theta_1$ and $\theta_3$, as the positions of your ...

3

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 extra current during stall (if there is extra current as I would also assume but would need to prove), which can be sensed and compared to normal stepping ...

3

From wikipedia http://en.wikipedia.org/wiki/Stepper_motor Because windings are better utilized, they are more powerful than a unipolar motor of the same weight. This is due to the physical space occupied by the windings. A unipolar motor has twice the amount of wire in the same space, but only half used at any point in time, hence is 50% efficient (or ...

3

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, three LM6UU 6mm Linear Ball Bearings, a stepper motor (typically a NEMA14/17/23 motor) and stepper driver electronics. These axes can then be connected to the ...

3

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 assume you can set up a timer which counts up to around 4 million and resets, and use that for the PWM. Assuming a two pole motor, 2042 RPM is 34 electrical ...

3

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 supply to the Hall Effect/Optical Sensor (with there being a separate Vcc or GND for the power). This is a basic schematic for a Hall Effect based device This is a ...

3

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 arm (5kg, 1m) Getting started with robotic arm design Choice of a motor for robotic arm The equation for torque is pretty simple. It is just force times ...

3

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 motor, with reduction gear and a potentiometer for position feedback, and electronic control. This is a common RC Servo. The fact that it has no ball bearings ...

3

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 a 100cm long snake robot with a motor every 10cm, the first/"neck" joint (at 10cm) needs to support 8 other motors and 90cm of snake body. The second joint ...

3

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 linear and defined as follows: \$ a\left(t\right)=\begin{cases} \Delta \cdot t, & t \in \left[0,0.025\right] \\ 2000 - \Delta \cdot \left(t-0....

3

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 speed vs torque Movement Profile Budget So we need a little more info about your system. You're dealing with a 10kg load and your linear vel. is very slow at 0....

2

#include <AccelStepper.h> //AccelStepper Xaxis(1, 2, 5); // pin 2 = step, pin 5 = direction AccelStepper Xaxis(1, 12, 6); // pin 3 = step, pin 6 = direction void setup() { Xaxis.setMaxSpeed(4000); //Xaxis.setSpeed(10); pinMode (3, INPUT); } void loop() { //Xaxis.runSpeed(); if (digitalRead (3) == HIGH) { //Xaxis.stop(); ...

2

You can do what yu want with the standard arduino "Stepper" library. You are using something called "accelsteper.h". Using the standard one.... This c-like psudocode will run a motor at some speed for 2000 steps then run and some other speed for 4000 steps and then go back an do it again. loop{ setspeed(speed1) step(2000) setspeed(speed2) step(4000) } ...

2

As long as the steppers are running relatively slowly, let's say a few hundred steps per second, you should be fine. Your driver uses PWM to control the current through the motor windings. In microstepping mode the driving waveform at the motor terminals looks like a sine and cosine (sines offset by 90 degrees) and the driver modulates the outputs to ...

2

It looks like the reason (one of) why the motor stops is due to the following code:- if (buttonState == LOW) { digitalWrite(startScan, HIGH); } else (buttonState == HIGH); --> this is a statement due to the semicolon. { digitalWrite(startScan, LOW); --> this statement will get executed even when buttonState is LOW. }...

2

I think you should look into the Arduino's attachInterrupt function. You would connect the buttons to a specific interrupt pin on the Arduino and then write a small simple interrupt handler that would be called when that interrupt fires. You can configure the interrupt to fire while low, on a rising edge, on a falling edge, or on a change of the interrupt ...

2

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

2

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 on standard Pololu DRV8825 stepper motor controllers. Note however that CNC platforms and 3D printer platforms have only three things in common: X, Y, and Z ...

2

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 motor and a "carry gear mechanism" so they can only count forward and backward (or in some cases only forward) in sequential order. general flip displays The ...

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