Questions tagged [torque]

Torque, moment, or moment of force is the tendency of a force to rotate an object around an axis, fulcrum, or pivot.

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8 votes
3 answers
9k 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 ...
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6 votes
1 answer
676 views

Roller Screw drive - axial movement instead of friction

I need an equation or a some hints to solve the following problem. Imagine a roller screw drive. I apply a torque of T to translative move my load mass ...
6 votes
2 answers
747 views

Static equilibrium for 7 dof manipulator

I have a 7 dof manipulator (Kuka LBR4+) and would like to calculate the joint torques needed to keep the arm in a static equilibrium. In most books the transposed jacobian is used to map the forces ...
5 votes
4 answers
3k views

Dynamic torque simulation for a 6 DOF robotic arm

I am working on a 6 DOF robotic arm(industrial manipulator). I have the basic structural specs (dimensions, weights etc) for the links and joints with me. Basically, I want to simulate both static ...
5 votes
3 answers
16k views

Torque in kg/cm?

I was looking up the motor parameters for some stepper motor where they listed the torque of the motor at different current/voltage but the torque they listed was in kg/cm. How is kg/cm even a ...
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5 votes
1 answer
188 views

Wind force impact on torque mechanical arm

I've got an arm attached to a shaft. The arms dimensions are 40x5 inches the arm weights about 10 lbs. If I have a wind acting on the side of the arm, how would I translate the wind force into torque ...
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5 votes
1 answer
4k views

Will wiring a unipolar stepper to a bipolar stepper driver decrease the holding torque?

I have read that you can wire a unipolar stepper to a bipolar driver, which I have, by ignoring the two extra wires. One concern I have is whether connecting a unipolar stepper to a bipolar driver ...
5 votes
1 answer
287 views

Calculating required torques for a given trajectory using Lagrange-Euler

I have a 2DOF robot with 2 revolute joints, as shown in the diagram below. I'm trying to calculate (using MATLAB) the torque required to move it but my answers don't match up with what I'm expecting. ...
4 votes
2 answers
6k views

Using brushless motors for very high torque

I'm currently building an robotic arm and I want the elbow joint to be comparable to a human one But here's the problem, electric linear actuators are too slow and have low torque, same goes with ...
4 votes
3 answers
985 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 ...
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4 votes
1 answer
5k 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
2 answers
790 views

What is the required theory behind building a robotic arm?

I am currently planning on building a robotic arm. The arm's specs are as follows: 3 'arms' with two servos each (to move the next arm) single servo clamp mounted on revolving turntable turntable ...
4 votes
2 answers
7k views

How to further understand the computed torque model controller

For the following controller what do $q_{des}$ and $q_{act}$ stand for? Also, what is the general principle of this controller? Thanks!
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4 votes
1 answer
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Why do series elastic actuators have more accurate and stable force control?

The other day, somebody was telling me about a robot in their lab, and they mentioned that it has "series elastic" actuators. But after doing a bit of Googling, I'm still not sure as to what this ...
4 votes
2 answers
4k views

Robotic arm select servo motors

Hi i´m designing a robotic arm based on this idea of the NOVABOT I only want to change its structural parts by aluminum tubes. In this design 3D model it use the servo hs-311 wish have a max torque of ...
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4 votes
1 answer
105 views

Attaching a M5 screw shaft to a cog wheel

Does anyone know of a good (low profile) way to attach the threaded (chamfered) end of a M5 screw shaft to a 30MM (30T 1M) plastic cog wheel? Would it be a good idea to widen the shaft hole and just ...
4 votes
1 answer
269 views

How is it possible to maintain the total thrust when controlling yaw of a quadcopter?

I'm working on the control of a quadcopter and I'd like to understand how come controlling the yaw does not increase the overall thrust. My understanding is that the control is carried out through 2 ...
4 votes
1 answer
102 views

Torque commands for velocity reference motor

I have a controller board for a motor, where I can read the motor current (to transform to torque), the position, the velocity and I can give a velocity command. There is not really a torque mode on ...
3 votes
2 answers
632 views

What are some ways to estimate torque/load on a robotic arm joint

My main problem is measuring joint torque/load economically. There are ways to detect the electric current drawn which is proportional to the torque. Since my motor is a BLDC motor, there will be a ...
3 votes
2 answers
102 views

Should the therotical parameters match the physical setup constraints when modeling a robot?

I'm working on modeling and simulation of robotic arm, after I obtained the mathematical model of the robot, I used that to implement some control techniques, to control the motion of the robot. The ...
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3 votes
4 answers
5k views

How Can I Measure the torque applied by a servo motor?

I believe that there must be a tool that can measure $oz-in$ of torque. I do not trust what the servo manufacturers state on their site for torque values, so I want to test them for myself. Can ...
3 votes
1 answer
217 views

Counterweight in arm designs

I wonder why most robotic arms use large J2 (shoulder) motors rather than counterweights. What sort of complexity do they add to the design beside increase in overall weight? In fact, rather than ...
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3 votes
1 answer
150 views

From a linear force actuator that spans multiple links and joints to the equivalent motor torque

I am programming/using a rigid body joint-space dynamics solver for robots in which I want to implement linear force actuators between links with their equivalent torque sources that are 'spanned' by ...
3 votes
1 answer
2k views

Why does microstepping give less torque?

I am experimenting with using a stepper motor for a robotics project. I'd like to use microstepping to give a better resolution and smoother movement, but I have noticed that the finer the microsteps, ...
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3 votes
1 answer
484 views

Torque required to rotate arm with mass at end

I have to calculate the required torque to rotate a point mass of 15N on the end of an 1.2m long arm which I have calculated to be 10kg in mass. The rotation must have a constant angular velocity of ...
3 votes
1 answer
87 views

Determining required torque for DC motor

How to determine the required torque while choosing a DC motor? Here is a simple scenario. Think of a 4WD or 2WD vehicle. The max load the vehicle will have is 100kg. Q1. How do I determine the ...
3 votes
1 answer
106 views

What should I be looking for in a DC motor that will be used in a UROV thruster?

I know that some DC motors produce a lot of torque but only actually move at a very slow rate, while others do the exact opposite. I know that I need some sort of balance between torque and the RPM's ...
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3 votes
3 answers
1k views

DC motor direct loading

I found many tutorials and online calculators for the selection of dc motor to drive wheel, I understood how the torque affect the driving of wheel. But what happen when I change the orientation of ...
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2 votes
2 answers
2k views

Jacobian of a 6DOF arm

I have a robot with 6 DOF. I read a lot of tutorial on how to compute the Jacobian, but usually all examples are for planar robots with 2DOF. I don't understand how can I get the Jacobian of a 6 DOF ...
2 votes
2 answers
356 views

No electric motors can handle being stalled for even short periods of time, even at low power. Is this statement true in all cases?

We were using a regular POLOLU d.c motor whose stall current is 0.36A. We want to use this motor in a robotic hand where the motor will be stalled while holding the object. We are limiting the current ...
2 votes
2 answers
4k views

What is the torque/force required to rotate the base of a robot arm?

Take a look at the following simple example robot arm: I want to know the torque required on that bottom motor to rotate the arm. Since it's not exactly rotating directly against gravity like the ...
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2 votes
2 answers
257 views

What is the torque transmission efficiency using a bycicle chain/setup for robot?

For this robot the gear attached to the motor is linked to the gear attached to the wheels by a bicycle chain (I am using a bicycle wheel and transmission set as the parts for the robots movements). ...
2 votes
2 answers
87 views

How to choose a servo motor for solar tracking mechanism?

I design a solar tracking mechanisim. You can see the very undetailed representation in the pic. For choosing a servo motor how can I calculate the torque etc?
2 votes
3 answers
4k views

Is horsepower related to torque in electric motors? [closed]

Is torque related to size or power at all in electric motors? And what about gas motors too? I have a go kart that is 2.5hp and it's 50cc and its about 1ft x 2ft x 1ft in size. I also see online ...
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2 votes
2 answers
375 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 ...
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2 votes
1 answer
536 views

Verifying motor selection calculations

I'm trying to select a brushed DC motor for a project. I tried following the advice on sizing electric motors, mentioned in this question, but a few details were missing, and I'm unsure if I properly ...
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2 votes
1 answer
115 views

Can I measure torque from this motor by only measuring the current?

I am new to robotics, please forgive/correct any errors. My Project Plan I want to use a PID controlled motor in a human-interface device where I need to measure the user's exerted force on an end ...
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2 votes
1 answer
6k views

Calculating screw breakaway torque

I'm trying to use motor-sizing tool developed by oriental motor to choose good servo motor for my cnc The tool requires breakaway torque of my screw as input, I searched online but I got people ...
2 votes
1 answer
85 views

Transforming position to torque

first question in this forum :D so i started creating a 2 link robotic arm in SIMULINK and made a function that builds its trajectory (cubic spline) and used it as an input for my joint. so my input ...
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2 votes
1 answer
959 views

Torque control and monitoring of servo

I am trying to control the servo motor operation by torque control by interfacing the sensor to an avr , which will continuously monitor the torque value from the sensor and control the torque ...
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2 votes
4 answers
94 views

Understanding the readings of Force Torque sensor based on accuracy and precision

I am working with a 6-axis force-torque sensor to measure the thrust and moments of a model jet engine. I want to understand the significance of the accuracy (measurement uncertainty) and precision (...
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2 votes
0 answers
87 views

How to calculate what motor I need to move weight

I'm working on a project trying to make some electric roller curtains. I can use 2 motors on this curtain, on each side to lift and pull down the curtain. Pulling down the curtain requires not as much ...
2 votes
1 answer
63 views

cable-controlled flexion and extension

I'm new, please be gentle :-) I'd like to control the position of a single-axis joint using one cable for flexion and another for extension. In many of the anthropomorphic designs I've seen each of ...
2 votes
0 answers
95 views

McKibben artificial muscles and the 400:1 ratio

I was recently reading that those artificial muscles had the highest power/weight ratio while electric motors only have a ratio of less than 100:1. As electrical engineer I have never worked with ...
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1 vote
2 answers
137 views

Suitable gear construction for a robotic extender - plastic?

I have a rather simple setup for my robotic extender. The DC motor turns a shaft with a worm on it. The worm connects to a small worm gear (green) which itself has a small gear (red) on the same shaft ...
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1 vote
1 answer
2k views

What servos are suitable for a robot like Boston Dynamics’ Atlas?

I have seen Boston Dynamics’ robot Atlas do some pretty impressive things, like a backflip, which must put quite large torques on the servomotors. What servos are there that can generate torques like ...
1 vote
3 answers
66 views

Is this supposed to be a bearing?

I'm looking at the assembly of a tail rotor that should look like this original image I wonder if the "tail output shaft stopper" (circled in red) is meant to be a bearing or just a piece of metal ...
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1 vote
1 answer
39 views

Force-torque sensor reading when a robot is stationary

Let's say I have a robot arm with a force-torque sensor on the wrist, between the final motor and the gripper. If the arm and wrist are stationary, then what would the reading on the sensor be? I know ...
1 vote
2 answers
513 views

How to maximize stall torque of a motor

I'm looking to use 3-phase motor without gearbox for robotics application. It will always work at near stall situation never rotating more than 360deg. I'm looking for arrangement that will produce ...
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1 vote
1 answer
910 views

Which kind of motors and how powerfull should they be for a robotic arm

I am building a robotic arm with these specifications: 1 meter long approx. 1kg weight it is made of 4 motors. (2 at the base. One for rotating the whole arm left and right and another one for ...