Hot answers tagged

10

The answer depends on the specific type of motor you intend to use, but in general: when a motor is loaded down, it draws more current, which means its windings get hotter at the same time that the cooling fan attached to the motor shaft is being slowed down. if this heat is allowed to build up, it will eventually cause the insulation on the windings to fail ...


8

It might be written that way because the transfer function of a second order system is written as: $$ h(s) = \frac{\omega_n^2}{s^2 + 2\zeta \omega_n s + \omega_n^2} $$ where $\zeta$ is the relative damping ratio and $\omega_n$ is the natural frequency. So in your system \begin{align} \zeta &= 0.7 \\ \omega_n &= 52 \end{align} It's easy to see ...


7

It depends on the specific type of motor, as @nielsnelson mentions, but it also depends on what you use to drive the motor. In general, a motor that's designed to run continuously isn't going to take well to being stalled for any length of time, unless its drive voltage (and frequency, if it's an induction or synchronous machine) is reduced. There are ...


5

At the very high level you will need 24V Power supply or a method to generate 24V 24V Motor controller Microcontroller - Arduino is a good place to start There are also prebuild motor controllers that can be programed via computer. These tend to be expensive. I would suggest following web sites similar to the ones listed below. They tend to have blogs, ...


5

Connect them with gears and they will run at the same speed - any sensor / control will have an accuracy range


4

The linear force of the rack is equal to the tangential force on your pinion teeth (less power lost due to friction, typically 2-3% for spur tooth and racks). Tangential force = torque/(pitch diameter/2).


4

The force which is needed to pull the pin out, will depend on the friction of the pin and the neighbouring material, and the surface at which the friction works. Let's assume a friction factor $\mu$ of 1, though it's probably less for plastics. That means that theoretically, just as much force is needed to remove the pin, as the force put on the pin by the ...


4

it's not unusual to find a single turn potentiomenter (aka pot) that provides a change in resistance over the range of the turning component. The benefit of a single turn pot is that you can get a large change in resistance with minimal movement. Volume controls are a good example. A multi-turn potentiometer is just the opposite. It provides a similar range ...


3

(Image from Wikipedia) When designing planetary gears, there are three different types of gear present to be designed: Annulus gear, an internal gear surrounding the other gears (shown above in red) Sun gear, an external gear in the middle of the gear set (shown in yellow). Planet gears, external gears surrounding the sun gear, usually three or four of ...


3

Operating principle is different. In essence if you buy just a motor it will be just that. You can now add gearing that will reduce speed and increase torque. Since torque is directly proportional to gear ratio and mechanical advantage; $$ MA = \frac{v_{input}}{v_{output}}. $$ You get a hundred times more torque if you gear 3000 rpm down to 30 rpm. So now ...


2

I have successfully used a non-stretch polymer known by various names such as Dyneema, GelSpun or Spectra for a similar purpose. It is easily purchased from most fishing supply stores. The material is extremely strong and non-elastic - some care is needed with termination since it is slippery. Crimps, wire loops and model aircraft clevises are all good ...


2

The fan starts to act like a resistor and soon will heat excessively, till the breaker cuts the power off. Almost all of the electrical motors have built-in fuses and breakers which will act to protect them. Combustion engines usually are tougher and if the torque demand increases beyond theire output they just stop cranking and you need to reignite them. ...


2

The simplest idea for me would be to add on the bottom (and the top cover) small inserts of the following shape (dimensions will vary depending on the size of the ball, etc) They would guide the ball towards the opening with the right velocity. You only need to provide adequate clearance for the rotating part, which from your side view should not be a ...


2

Instead of a Servo, this could be very easily be done by the combination of a spring and a linear magnetic actuator. The downside is, that the setup needs a minimum weight of the item to overcome the closing spring. Upon detection of the hand, the actuator retracts the locking bar and the weight of the item pushes the door open against the spring. As the ...


2

If you look at some common vending machines (I'm talking about the ones that hold snacks), They dont use a servo. Instead they have a motor turn a screw/coil continuously until the purchased item pushed along drops from inside the coil, tripping a simple sensor (like a limit switch) which tells the motor to stop. Feedback ensures the purchased item is ...


2

I'd personally go with Magnetic actuators, as those are highly reliable and can flip between their states extremely fast. As they are providing linear motion in a rather short range, you would need some lever on the hinge, but the part itself can be the hinge. Most magnetic actuators also have a rather small build volume, so the actuator might even be ...


2

Is the power calculation same when I have a Rack and Pinion or a Lead Screw? Yes and no. Either power calculation needs to take the efficiency of the gearing into account, but you can pretty much count on the efficiency of the rack & pinion being much better than the lead screw. In fact, lead screws (and worm gears) are often used because they have ...


2

There can be another case: if the motor is expected to stall time to time or experience an overload condition as a part of its routine, motor shaft can be equipped with a ball detent torque limiter instead of a fixed gear. That way, the motor can keep spinning in idle mode without notable damage while its working piece is blocked-by.


1

Adding to the other answers. I just so happen to have done exactly this. I used a windshield wiper motor and a potentiometer but the principal is the same. Here's my arduino source code: https://pastebin.com/0ezsmi4y And a short video I took of it in action. This is an alternate version that takes RC PWM input instead of serial. I think all the talk about ...


1

You are at the right track. As the DC motor is rather fast for a potential slow microcontroller, using a discrete controller will improve the reliability and stability of the closed-loop system. Even though a DC motor is rather easy to model (speaking of the basic dynamics upto the 3rd order), using system identification can improve parameter estimation ...


1

Integrators is just a fancy way of saying you want to check your results. A type 0 system simply does not check the result at all. A type 1 system is reading the position directly from the shaft for example. So if there would be any unknown load etc in the system then you could compensate for this position error. Whatabout a type 2 system? Well since you ...


1

If space is tight and complexity must be minimized, why not just buy a servo that has 90 degree travel to begin with. There are a number of these available for cheap.


1

If I understand your design correctly you extend the existing play in the mechanism. If you can’t eliminate the play then you can try to minimise it. See the locking pliers (https://en.wikipedia.org/wiki/Locking_pliers) as an example to reduce the play. The disadvantage of this principe is the distance decrease.


1

You can use a one to one worm drive, even though I don't see the advantage. Also as has been mentioned in other answers there are many cluching- locking mechanisms that need either a mechanical or electrical switch to release. Aviation industry commonly uses all manner of cluch and release in applications such as the hinge connection of propellers to shaft ...


1

A worm drive presents a reduction with a ratio of one to the number of teeth on the driven gear. This means it would be necessary to have a gear with one tooth and yet remain circular. Obviously not in our universe. Thanks to Phil Sweet, I've become aware of multi-start worm gears, also called multi-threaded worms. This would improve the mechanism by ...


1

The dynamics you’re looking for are largely governed by how you connect the different components in your design. Although the hydraulic pump you select is important, the equations provided in the supplier catalog should (at least) be sufficient for an initial design analysis (i.e. make an assumption with respect to pump’s efficiency by using the provided ...


1

An easy solution is to use a Motorized Linear Slide Pot - they're not expensive and they have a motor and a pot - you still need to build the feedback loop to control the position and use a DAC to provide a voltage for the setpoint. A mechanical linkage can reduce the range of motion to what you require.


1

A hobby r/c servo is centered when the pulse width is (nominally) 1.5mS, or in the case of a continuous rotation servo, when the servo is not moving. i.e. the servo motor is perfectly idle with no current draw. Simply connect the servo to a receiver/MCU with an analog input and adjust until the servo stops moving. No need for a servo tester.


1

How about using a Plastic Water Solenoid Valve - 12V - 1/2" Nominal coupled with 1/2" to 1/4" adapter. You could use simple arduino microcontoller to control the valve. Below are some example images of the hardware.


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