7
votes
Accepted
Using brushless motors for very high torque
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 ...
- 725
6
votes
What are some ways to estimate torque/load on a robotic arm joint
Model Based:
Low cost solution is always software:
Develop a dynamic model which computes the load on the motors based on the motions (e.g. with Recursive Newton Euler Algorithm or Lagrange-Euler ...
- 6,682
5
votes
What servos are suitable for a robot like Boston Dynamics’ Atlas?
The Boston Dynamics’ Atlas robot doesn't actually use servo motors. It uses electrically-powered hydraulic actuation.
I saw a presentation by Boston Dynamics' Marc Raibert where (if I remember ...
- 1,074
5
votes
Jacobian of a 6DOF arm
Write the forward kinematic equations $$\vec(x) = F\vec(\theta)$$
Taking the partial derivatives of each $\vec (x)$ term with respect to each joint variable $\vec(\theta)$ will give you $J$.
- 4,406
4
votes
Dynamic torque simulation for a 6 DOF robotic arm
The dynamics of robotic arms are fairly complex, especially when there are more than three joints to consider. The problem is that the movement of each joint moves all the links beyond it, which can ...
- 218
4
votes
Accepted
What types of actuators do these industrial bots use?
Actuation is a complex subject that cannot be reduces to 1 component alone. It is the interaction of software electronics and mechanics. "Toy" servos tend to incorporate everything in one small ...
- 6,682
4
votes
What is the torque/force required to rotate the base of a robot arm?
You need enough torque to overcome friction, and to accelerate the load.
If you know the friction torque ($\tau_f$), and the mass moment of inertia along the motor axis ($I$), then the minimum motor ...
- 385
4
votes
No electric motors can handle being stalled for even short periods of time, even at low power. Is this statement true in all cases?
Electric motors designed for stall torque can handle stall torque just fine. One giveaway sign of high stall torque motors is forced cooling (cooling with a powered fan and not just a fan mounted ...
- 6,682
4
votes
Accepted
Will increasing voltage on brushless DC motor increase torque, if speed is kept constant?
It depends on various other factors as well. If the motor outputs 60RPM @24V under load, given the motor is rated for 12V - 60V and the load is kept the same, then by doubling the voltage from 24V to ...
- 71
3
votes
Accepted
Will this have more or less lifting strength
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 ...
- 15.9k
3
votes
Accepted
How to get Max Torque on Robot arm 's Joints (RRR)
Torque is pretty easy to calculate for a single static arm configuration. Torque is just the length of the moment arm * the perpendicular force. And it is easy to decompose the problem into X and Y ...
Ben♦
- 5,865
3
votes
Dynamic torque simulation for a 6 DOF robotic arm
I think you may be going about this problem wrong. If you find a simulator that reports joint torques, then what? Are you going to iterate through every possible start and end location?
You should ...
- 15.9k
3
votes
What types of actuators do these industrial bots use?
A robot like the one you refer to probably has a mix of transmission types that increase in power-to-weight ratio and decrease in size and stiffness as you move outwards on the kinematic chain. The ...
- 106
3
votes
Accepted
What is the torque transmission efficiency using a bycicle chain/setup for robot?
I agree with @Andy 's answer, that chain efficiency is over 90%. I'll point out that your terminology is not quite right - using bicycle chain (or any other transmission) affects power transmission ...
- 15.9k
3
votes
Which kind of motors and how powerfull should they be for a robotic arm
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 ...
Ben♦
- 5,865
3
votes
Accepted
How to maximize stall torque of a motor
One relevant equation is the lorentz force equation. which suggests that if you want to reduce current then you need to increase the magnetic field.
The magnetic circuit is complex, with different ...
- 4,445
3
votes
Accepted
Specification calculation for choosing a proper stepper motor for Ball Lead / Screw system
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 ...
- 553
3
votes
Quadrotor dynamics: How is torque created
Each motor generates torque to spin it's fan. As the fan turns, the quadrotor will experience the same torque on the frame, only in the opposite direction.
This is similar to a helicopter - the tail ...
- 131
3
votes
Accepted
Force-torque sensor reading when a robot is stationary
The answer is $\vec{G}$! and also any $\vec{\tau}$ torque caused by it, if the axis connecting the geometrical center of the sensor (assuming it measures torques relative to its geometrical center) to ...
- 6,682
2
votes
Is horsepower related to torque in electric motors?
What is horsepower?
Horsepower is a measure of power (work done in a specific period of time - the higher power, the more work done), just like watts or kilowatts. $ 1 hp \approx
0.75 kW$ In case of ...
- 953
2
votes
What is the torque transmission efficiency using a bycicle chain/setup for robot?
From a cyclists' perspective - a good modern bike chain transmission is very efficient - percentage efficiency is somewhere in the high 90s and has been for decades.
(From anecdotal evidence: endless ...
- 1,061
2
votes
Accepted
Calculating screw breakaway torque
You can approximate the breakaway torque by considering static friction only. From the static friction coefficient of the lead screw (by knowing the maximum load on the spindle, coming from the ...
- 6,682
2
votes
Accepted
Robotic arm select servo motors
There are two general categories of servos, hobbyist and industrial. Hobbyist ones generally go up to about 50kg/cm, and some will do more than that but costs multiply (sometimes these are called ...
- 266
2
votes
Robotic arm select servo motors
Well it seems that length is your problem.I came here having a similar problem to yours with designing a robotic arm. Servos that can pull this weight go for 500+ USD. Adapt the length and weight of ...
- 21
2
votes
Accepted
From a linear force actuator that spans multiple links and joints to the equivalent motor torque
Yes, it is the Jacobian transpose.
The Shadmehr site you cited has been reorganized. The "Forces and torques" chapter is linked to by the lab's publication page.
The F&T chapter has the ...
- 1,301
2
votes
How to calculate effort/torque values of a joint
The wrench characterizes the forces and torques acting on the respective linkages. Part of this is motor torque, the other forces and torques are loading the mechanical structure (and motors down the ...
- 6,682
2
votes
Counterweight in arm designs
The weight of the motors is less then the weight of the gears and bearings in the joint. So moving the motors only not that advantageous. Moving the gearboxes can be done, but bearings still need to ...
- 6,682
2
votes
Accepted
Can I measure torque from this motor by only measuring the current?
Can I use current sensing to measure the torque on a wormgear drive?
Nope as the worm-gear is not back-driveable by construction.
what would be the best path forward?
Using an FT sensor mounted at ...
- 4,005
2
votes
How to choose a servo motor for solar tracking mechanism?
Most solar tracking rigs only move along one axis because the efficiency savings from moving along 2 doesn't make up for the energy losses of having 2 motors.
If you're just doing this for fun, then ...
- 41
2
votes
How to choose a servo motor for solar tracking mechanism?
Servo 1. Referring to your diagram, first consider the tilting part at the top. Imagine a line connecting its bearings. It will tilt (rotate) about that axis. The weight (force due to gravity) of the ...
- 1,301
Only top scored, non community-wiki answers of a minimum length are eligible