# Questions tagged [motor]

Without qualification 'motor' is usually taken to mean a rotary electromechanical motor, typically either a brushed or brushless design.

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6k views

### Robot never goes straight

I am using 2 identical DC motors and a castor wheel. The motors are connected to L293D motor driver and are controlled by RPi. The robot is not going straight. It veers off to the right. I am ...
52k views

### Preventing leaks in motor shafts for underwater bots

Whenever building an aquatic bot, we always have to take care to prevent leakages, for obvious reasons. Now, holes for wires can be made watertight easily--but what about motors? We can easily seal ...
8k views

### Simple equation to calculate needed motor torque

Suppose I have a DC motor with an arm connected to it (arm length = 10cm, arm weight = 0), motor speed 10rpm. If I connect a 1Kg weight to the very end of that arm, how much torque is needed for the ...
12k views

### How do I calculate the required loop frequency for a servo controller?

I have a motor which drives a string connected to a load cell. I would like to implement a closed loop controller to control the load applied by the motor to the string. How do I go about determining ...
4k views

### Choosing motor for a tricopter

I'm a newbie in RC field..I am planning to construct my first Tricopter ever. Can anyone help me to find the power rating to select the motor for a tricopter? I am at the beginning stage of ...
5k views

### Is there a way to use a single dc motor output for two different loads?

Is there a way to use a single dc motor output for two different loads (by using gears, relays etc) ? Please see the illustration below: To clarify the illustration, I get the dc motor power at "...
665 views

### Keeping two wheeled wall following robot straight

I have a two-wheeled (two DC motors) robot that needs to follow the wall beside the robot. The issue is that the DC motors spin at different rates (because they are not identical, of course), so the ...
354 views

### 2Nm small motor

Currently designing a spherical wrist, I want to manipulate a 300gr payload. the design has a 200mm span, so I'm guessing at a 1.1Nm (considering the weight of structure & motors). I've looked at ...
1k views

### Is the nominal voltage of a motor the voltage to apply to the motor?

I have just sized the DC motors I want to use (corresponding to my robot and its intended applications - my figures include a 50% uncertainty factor to account for friction in reducers and other ...
106k views

### Why are capacitors added to motors (in parallel); what is their purpose?

I've seen many motors having capacitors attached in parallel in bots. Apparently, this is for the "safety" of the motor. As I understand it, all these will do is smoothen any fluctuations--and I doubt ...
109k views

### What is stall current and free current of motors?

What are the stall and free currents of an electric motor? For example, this Vex motor lists its stall and free currents at the bottom of the page. I think I understand the general idea, but a ...
855 views

### Are power and torque required related in some way?

I am designing a new platform for outdoor robotics and I need to calculate the power and/or torque that is needed to move the platform. I have calculated that I need about 720 W of total power to move ...
4k views

### Building a controllable "knob"

I am trying to build a semi-analog timer. Something like those old egg timers that you rotate the face of. I want a knob that I can turn that can be read by a microcontroller, and I also want the ...
3k views

### What are the different types of electric motors?

I am beginning to learn about the hardware aspect of robotics, and in order for a lot of this new information to be useful to me (whether on this site or elsewhere) I will need a basic understanding ...
543 views

### Arduino Motor control

I'm working on a rather low budget project, and need some way to control four or more motors using one Arduino. I've looked at motor shields a little, but I have a shield on top of it already, It does ...
330 views

### Prototyping a device with 25-100 small DC 3.0V motors, is Arduino a good fit?

I want to prototype a therapeutic device that will have a lot of tiny mobile-phone type vibration motors like this one in it, and I want to be able to activate them in any configuration I want. I'm ...
271 views

### Best way to estimate velocity of motor with encoder

I'm designing a PMSM controller with the motor has an optical encoder, so I can get position information from the motor. But how to measure the velocity of the motor. Now, my design is to calculate ...
427 views

### What kind of sensor do I need for knowing that something is placed at a position?

I have a small device that's picking up small rocks from a pile and moving them to another place. Its a kind of crude way of trying to push the whole pile onto a bigger gear and hoping one of them is ...
1k views

### Upgrading the motors on a SeaPerch ROV - more torque, or more RPMs?

I am looking to upgrade the motors for SeaPerch underwater ROVs so we can carry heavier payloads and more equipment. My question is, should I look for motors which have a higher RPM and lower ...
407 views

### Dealing with position inaccuracy and latency in PID Loop

Background: I am new to PID, for my first PID project I am using a simple P-Loop and 300 degree linear potentiometers for position feedback. I am using the roboclaw 2x60A motor controller. The motor ...
690 views

### What do we call a coupling with infinite range of rotation

In most situations, range of motion is limited by the fact that we need to carry power or information past a joint. So, past a certain point there are either cables in the way, or the cables would ...
6k views

### Single-shaft vs Double-shaft motors

I am trying to make a line follower robot and I need help regarding the type of dc motor to use. So we have a single shaft BO Motor and a double shaft BO Motor. Can anyone help me understand what is ...
13k views

### Choosing DC motor: max needed torque vs nominal torque

I have just sized the DC motors I want to use (corresponding to my robot and its intended applications - my figures include a 50% uncertainty factor to account for friction in reducers and other ...
2k views

### Length and Width of a Line Following Robot

I'm building a line following robot. I have made different chassis designs. The main prototype I'm using is a rectangle base. At one side motors are placed. On the other side of the rectangle caster ...
1k views

### Low Amp FPV Quadcopter Motors

Why do FPV Quadcopter Motors (usually the more expensive ones) draw lower amps than regular motors? And why are they more squat(disk shaped) as opposed to normal motors which are about the same ...
2k views

### H-bridges and stall current

For a DC motor with a stall current of 950 mA, what should the H-bridge's current rating be? What will happen if we use our H-bridge L293D whose max. output current is 600 mA?
1k views

### Building a non rotating persistence of vision device

I'm looking for a way to create a non-rotating persistence of vision device. I have all the electronics set up but I'm stumped with the mechanical design. I tried these two designs: But these didn't ...
186 views

### Stated power for a motor does not equal nominal voltage x current?

I have just sized the DC motors I want to use (corresponding to my robot and its intended applications - my figures include a 50% uncertainty factor to account for friction in reducers and other ...
557 views

### Rotate (and stop) a large disk in very tiny increments

In a lab build I'm doing, I'm stuck at this problem, so I am fishing for suggestions. I'm creating a turn-table type setup where I need to make readings (with a nanotube-tip probe I've already ...
158 views

### Continous rotation with cables

A motor needs to spin n*360 degrees. On top of the motor there are distance sensor which scan the room. I.e. lidar. What options do I have for implementing a continous rotation while having cables ...
2k views

### How high of a gear ratio can a motor have?

I want to make a robot arm where a joint is powerful enough to lift 8 kg up at a distance of 1 meter. This requires torque $tau = r*F = r*m*g$ = about 80 nm. So now I am trying to find the ...
233 views

### How do I convert centre-returning joystick values to dual hobby-motor direction?

Currently my setup is: 2x hobby TT motors connected to a Pi Zero with a motor HAT Python script running on the Pi which runs a Blynk python client and controls motors via the gpiozero library Blynk ...
364 views

### How do I interface a TLC5947 with small motors?

This is a follow-up to this question: Prototyping a device with 25-100 small DC 3.0V motors, is Arduino a good fit? I've decided based on the answer that sending the control signals through multiple ...
350 views

### Flipping an old manual switch (physical one) [duplicate]

I Have an old audio amplifier that has those switches to turn it on. I'm looking for the simplest motor/robotic arm (or any other relevant component) to control this switch - eventually via Raspberry ...
53 views

### Motor driver damage and jerking behavior when load driving in same direction as motor

I'm having trouble with a gear motor being powered by a power supply, while it is being driven by the load in the same direction as the driver wants to drive it. Here is a simple diagram: The gear ...
676 views

### How can I attach an arm to a double-flat drive stepper motor?

This is my first robotics experience, outside of one class 10 years ago. I've been Googling this question for about an hour but I can't find an answer! I'm using a ROHS Step Motor 28BYJ-48 (with an ...
377 views

### Selecting a gear reduction: torque vs speed

I have just sized the DC motors I want to use (corresponding to my robot and its intended applications - my figures include a 50% uncertainty factor to account for friction in reducers and other ...
1k views

### Need super-basic help with motor encoder

So I have this motor: https://www.servocity.com/23-rpm-hd-premium-planetary-gear-motor-w-encoder and this motor shield for my arduino uno: https://www.pololu.com/docs/pdf/0J49/...
147 views

### How does the "rated torque" for a gear relate to the maximum torque?

I have just sized the DC motors I want to use (corresponding to my robot and its intended applications - my figures include a 50% uncertainty factor to account for friction in reducers and other ...
402 views

### Relation between Power, Weight & Speed

Motor I am going to use these 100rpm 12Volt Motor supplied Power given below. Surface Surface will be Plain Wooden. Area of contact between 6 Tyre and surface would be maximum of 4cm2 in total. Use ...