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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57
votes
2answers
101k 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 ...
38
votes
11answers
48k 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 ...
34
votes
4answers
100k 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 ...
19
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6answers
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 ...
16
votes
4answers
7k views

Will connecting two servo motors double the torque?

For my robot, I am using two continuous rotation servos to spin a threaded rod. I am trying to make this project as cheap as possible. Here are the servos that I can find: Servo #1: This is a very ...
14
votes
1answer
1k views

Will turning an NXT motor by hand damage it?

I have heard a lot of claims that manually turning an NXT motor by hand can potentially damage it. I was wondering whether this was at least partially true, and whether there is any evidence to ...
13
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5answers
39k views

How to convert vertical motion to horizontal?

I am interested in using this miniature motor Squiggle Micro Motor to create very tiny horizontal movements. However, due to very limited space, I can only place it vertically within my project. ...
13
votes
2answers
346 views

How can I detect if a DC motor on a robot is starting to fail?

What characteristics can I look for which could be reliable early warning signs that a DC motor on my robot, say one used for the drive, could be failing? I'm looking for an answer that deals in terms ...
12
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1answer
1k views

How to get two continuous tracks (tank treads) to move at the same rate?

I've got a couple Vex 269 Motors hooked up to an Arduino Duemilanove. These motors run a some Vex Tank Treads. The two motors are run as servos on the Arduino using the Servo Library. The problem I'm ...
12
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3answers
928 views

What determines the amount of noise an actuator produces?

Many robots and other mechanical devices produce the signature whirring noise as they move, some produce less. What makes the difference? What restrictions a silence requirement places on a robot?
12
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1answer
17k views

How is a brushless gimbal motor different from a regular brushless motor?

How are the brushless motors in a gimbal assembly designed? Obviously it doesn't need continual rotation, but it does need accurate control of precise position. I've noticed that the motors in my ...
11
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2answers
11k 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 ...
9
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2answers
766 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 ...
8
votes
3answers
7k 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 ...
8
votes
4answers
409 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 ...
8
votes
1answer
4k views

DC motor control - speed-torque curve

I am having some trouble understanding how to practically use the speed-torque curve of a DC motor. I understand that the gradient of the speed-torque curve is defined by the design of the motor, the ...
8
votes
5answers
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 ...
8
votes
2answers
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?
8
votes
1answer
1k views

Increasing the rotation range of a servo motor

How do I increase the rotation range of a standard servo? Most servos have a rotation range of ~ 180 degrees. I would like to access the entire 360 degree range on the servo, partially because I would ...
8
votes
1answer
292 views

How can I upgrade an existing robot with a higher torque, sensored motor @ ~100 watts?

I would like a high torque motor (37 oz-in @ 5760 rpm) for souping up a Scorbot 3 I bought. I really need it to have an encoder to count the number of revolutions and to allow high start-up torque. So ...
7
votes
2answers
2k views

Why does our LM2576 circuit suddenly cut down the power?

I have an LM2576 circuit plus an adjuster to adjust the output voltage, for controlling motor speed in a line follower robot. The circuit works great when adjusted to give out low voltages, but when I ...
7
votes
3answers
912 views

Reducing motor speed without jamming up

So I built three little bots so far. One with a raspberry-pi, (6V motors), one with an arduino (12V motors), and another with an arduino but a hacked remote car (7ish, volt motors): The problem I ...
7
votes
2answers
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 ...
7
votes
5answers
529 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 ...
7
votes
6answers
9k views

What mechanical parts can be attached to DYJ48 stepper motor?

Sorry I am asking a mechanical question here, but, after all, where else people have experience with using motors? If there is a better forum for this, please do guide me. Everywhere I've seen online,...
7
votes
1answer
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 ...
7
votes
2answers
4k views

I want to control a sewing machine motor; need help with choices

I've got an industrial sewing machine (think "can sew with thread that looks like string, and has no trouble pounding through 20 layers of Sunbrella fabric"); it's got a 1 HP motor to power it. (I've ...
6
votes
4answers
13k views

What is the difference between RC motors for cars and helicopters?

I am working on a robot with focus on speed. At the moment I am looking for a suitable motor but it world help if I understood the difference between the various options. To provide some background, ...
6
votes
1answer
177 views

Do 6 motors require 6 individually-assigned batteries?

For the Dagu Wild Thumper 6 Wheeled platform, or any multiple motor system, do I really need 1 battery for each motor? Or should I just buy 2 for either side of the platform. In addition, for larger ...
6
votes
2answers
4k views

Programming an ESC to have reverse mode

How do you program an ESC to have a reverse mode? We're looking to control an ESC from a servo board (for a robotics project). Assuming that the input will be between 0 and 255, we're looking for 127 ...
6
votes
6answers
13k views

How to check for a sharp angle with a line follower?

I have the mBot robot and I want to program it to follow the line. So far it can pass any kind of line that is >90°. I want it to be able to pass 90°-ish angles as well. Like this one: The problem ...
6
votes
2answers
231 views

Do servo motor specifications take into account the gear ratio inside?

I am looking at buying a servo motor for a an application that must be able to lift 4-5 lb at a rotational speed of approximately 1rpm. The servo motor listed here http://www.robotshop.com/ca/en/hitec-...
5
votes
5answers
9k views

High voltage motor control with arduino

I'm trying to control a higher voltage motor than an arduino can source with a pin, with an arduino. I am trying to hook it up to a transistor. The battery pack is not supposed to be 4.8V, it's 6V, 4 ...
5
votes
2answers
1k views

Relationship between motor torque and acceleration

I am working on designing and building a small (1 1/2 lbs), 2-wheeled, differential drive Arduino-controlled autonomous robot. I have most of the electronics figured out, but I am having trouble ...
5
votes
1answer
296 views

Why to combine a Raspberry Pi (or similar board computer) and an Arduino for controlling motors?

I am planning to build a omnidirectional holonomic robot, and checking what I should use for the hardware, I saw many people using a Raspberry to compute most stuff, which in turn calls an Arduino to ...
5
votes
2answers
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 ...
5
votes
1answer
339 views

Handling PID DC motor control at low speeds

I am building a 4 wheel rover and am using PID DC motor control for the back set of wheels. The feedback for the speed is provided by Hall effect sensors, with two pulses per rotation. This means ...
5
votes
2answers
238 views

What kind of motor control can I implement if I cannot use an Encoder?

Every time I see a PID control for a motor, it involves an Encoder, so the algorithm knows the real position of the motor or wheel. But with the robot I have, I cannot use an encoder. I only have ONE ...
5
votes
1answer
5k views

Quadcopter Throttle and PID mixing to Motor Speed

I've been writing some quad copter software and I am not sure what the best way is to map the throttle and PID inputs to ESC power. My throttle range is 0-1 and my PID outputs are 0-1. My ESC's have ...
4
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4answers
1k views

How to raise/drop a spider?

For Halloween, I'd like to build a spider that drops from the ceiling when it detects motion and then rewinds itself back up to scare the next kids. I already have a lightweight foamish spider from ...
4
votes
3answers
4k views

Harmonic drives in hobby projects

After a fair bit of research into industrial robot arms I've learned that a lot of them use components like harmonic drives and sometimes cycloidal gearboxes. Two main questions: How feasible are ...
4
votes
3answers
848 views

What types of actuators do these industrial bots use?

I have a particular example robot that interests me: http://www.scmp.com/tech/innovation/article/1829834/foxconns-foxbot-army-close-hitting-chinese-market-track-meet-30-cent See first image, the ...
4
votes
1answer
4k views

Calculating Required Torque

Say I had an object with 4 motors/wheels attached (in a fairly standard arrangement). I need to calculate the amount of torque required from the motors to be able to move the object of x kilograms ...
4
votes
2answers
4k views

Choosing motors for 2 wheel drive robot

I am making a 2 wheel drive robot. Suppose I know that my robot is going to weight x kg when finished and I know the diameter of the wheels y (geared motors will be connected directly to the wheels). ...
4
votes
2answers
3k views

Quadrature encoder signal from dc motor is very noisy

I'm starting out with robotics, got my first DC gear motor with quadrature encoder (https://www.pololu.com/product/2824): I ultimately plan to hook it up to a motor driver connected to a Tiva ...
4
votes
2answers
3k views

For robot wheel control : Brushless DC motor or Servo Motor?

Simply, when to use brushless dc motor and when to use Servo Motor ? what are the differences , specially when adding an encoder to the dc motor you can have the position and it will be similar to ...
4
votes
2answers
714 views

What is the opposite of 'Antagonistic'?

A robotic joint is connected to two actuators, e.g. air muscles. One flexes the joint, while the other extends it. This arrangement is called 'antagonistic'. But what if I had an electric motor ...
4
votes
1answer
246 views

What is the purpose of electronic braking in motors?

I have a Micro Magician v2 micro controller. It has a A3906 Dual FET “H” bridge motor driver built in. In the manual it states "Electronic braking is possible by driving both inputs high." My first ...
4
votes
4answers
7k views

Electric Motor Speed Control - PWM vs analog voltage?

I'm working on a 2-wheeled robot and have connected up a raspberry pi to an L298N motor driver. I'm sending the enable pin of a particular motor a software-generated PWM signal at 100Hz with a 50% ...
4
votes
2answers
295 views

Should I use an arduino to control my balancing robot's motors?

I'm building a 2-wheel balancing robot from old parts. DC motors from an old printer, wheels from a BBQ, bodywork from an old optical drive etc. The brain of the robot is a Raspberry Pi 3. I'm using ...

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