I´m just wodering how you would go about reading output torque from a system that is powerd by a motor
Welcome to SW forums Gubbar
Check Plotting Torques if it what you looking for.
Also read this post for your future reference: Forum Posting
As i see, motor can be included in concentric joints. We can get the value of motor torque curve with the motion analysis result. But when i include GRAVITY the torque requirement is enourmously increased.
My doubt is to get the torque value of motor does we have to include GRAVITY or NOT.
If you are really looking for an answer, including a sample file would make it easier for us to help you.
Generally speaking, as you are doing a physics based solution, if you want an answer that means something, then yes you should include gravity. If adding gravity suddenly gives you a very unexpected result then you need to look closely at your model and setup. Things like redundencies, joint properties and friction values. Just don't jump on the onld bandwagon of "it must be a bug in SW" because most (but not all) of the time it is an improper setup of the problem. Use you skill and knowledge as an engineer first and then let SW crunch the numbers.
This Assembly doesnt have more joints. A motor is in Brown color, A length of 1000mm and 1kg locked to the length. The length is made concentric mate to the motor.
I gave velocity profile to the motor in DATAPOINTS with at 0sec =0 deg/sec, at 1 Sec = 1deg/sec, at 2 sec= 1deg/sec ..
When Calculated by motion Analysis (add-on-SOLIDWORKS MOTION) , result for the motor Torque is only 17 Nmm is the maximum, here gravity is suppressed.
When Gravity is enabled(unsuppressed) the Motor maximum torque ploted is 10,000Nmm. In both the cases the motor's maximum Angular Acceleration is 1 deg/s2.
This is the problem. But thanks for the reply.
Why do you think that this is the wrong result?
As you did not supply the model, I made a simple 1000mm bar and set the mass at 1kg. In your picture, you appear to have a spherical mass at the end of the bar away from the motor. Assuming that the total weight is still 1kg, the center of mass of your system is more than 500mm from the center of rotation, but I don't know where exactly as you haven't provided any details. Is the sphere 1KG? If so, what is the mass of the bar?
I did a simple test just using the bar alone with its mass of 1KG centered on the bar. Assuming a starting postion where the bar is horizontal and the motor direction is rotating the bar upward toward the 12 o'clock postion. With no gravity the motor torque is 5 Nmm as all the torque is doing is overcoming the momentum of the mass and at 1 second the torque falls to zero as there is no friction in this study. If you add gravity, the torque is about 4900 Nmm which is just what I got by doing a hand calculation as the torque has got to lift the bar. You have 1KG on a 500 mm arm. Most of the torque is just what it takes hold the bar level. As your center of mass is on a longer arm, your torque is going to be higher. When I moved the center of mass of the bar to the end away from the motor, the torque to hold the bar level is 1 KG-M or 9806 Nmm before you even start to rotate.
Basically, most of the torque in this problem is rotating the mass against gravity as the acceleration due to the change in motor speed is very small.
Thanks for the reply.. I dont know how to upload the .zip file. But anyway you all asumed and simulated in a right way what I did and got..Great.
Why I am saying it may be wrong answer is, I do want to attach to a stepper motor this load. To just lift one kg of weight with 1 m distance is asking for 10Nm holding torque of stepper motor means. I feel it is too much high.
Because the ARM ROBOT done by many companies to lift 6kg payload at a distance of 1 m, using just 8Nm of Stall torque motor at the base and 1st axis.http://www.alliancerobotics.com/used-fanuc-parts/Fanuc-Motors.cfm
How it was possible.
so I thought we were something wrong in it.
For future reference, if you need to attach a file, you use the "advanced editor" by clicking "use advanced editor" in the upper right corner of the reply window. IN the Advanced editor there is a box at the bottom to attach files.
As for the motor size, since you cannot violate the laws of physics, there are only two solution I see. First the arm has to be nearly vertical in use which shortens the effective arm length to the gravitational load. Or, the most likely way is mechanical advanntage through the use of gears. Otherwise, lifting a 6KG load at one meter requires about 59N
Yes... You are correct...Right answer is using the gear Box. If we reduce the speed by gear we can increase the torque. so as per Gear Ratio we can increase the torque level.
Here I have attached a assembly which has one gear arrangement of Gear Ratio of 2. I connected a motor and accelerated the motor. Both the wheels are rotating. I can find the torque of the motor by ploting motor torque in result, where first wheel is attached. Can i find the how torque i have extracted from wheel2 where gear is attached ?
One more doubt is can i include the Speed-Torque Characterists of the motor given by motor manufactures, to the SOLIDWORKS motor? I tried the constant power motor by torque motor by writing expression to the torque value=power/velocity. But this is linear one. I want to import the exact the speed torque character to the motor.
Thanks for the answer. It helped me and saved my another 2 days spending time on this.
Why do you want to include the Speed-Torque characteristics of the motor? The way the analysis works is that the motor will do exactly what you tell it to do as far as displacement, velocity or acceleration as it has the capability of infinite power. If you tell a motor to displace one meter in one second, it will do exactly that regardless of whether it is moving 1 gram or 1,000,000 tons. You then use the results to know what torque, power, etc. is required to run your system and you buy a motor that meets those characteristic.
If you want the motor characteristics to change, based on some variable, then you need to use that variable in an expression to define the motor. The only trick is that to have the create a plot of that variable first so that it will show up in the Motion Study Results list in the Function Builder.
If you have a plot, then define it using the Data Points or Segent options and the proper choice of curve smoothing.
Look in the Help file to figure out how these work.
Oh..God until these days I dont know there is drop down menu in the expression list, I only saw mathematical expression and w.r.t time as x axis. You opened eyes thank you.
But another question I asked is about getting torque extracted from the gear mate. i.e. By reducing the speed we can increase the torque.
Eg: When i included a motor that has constant power expression(it has speed-torque characteristics inlucled in datapoints) when i coupled this motor to another rotating wheel via gear mate. But increased diameter.
I want to know the torque of the rotating wheel which is mated by gear with ratio of 2.(reduced the speed by 2). How to plot torque of the wheel.
Your answer is ok when i know the application's weight and speed of Action.
But When I want to deduce the application based on Motor torque and power means , First i have to fix the Torque-Speed Characteristics of Motor, Then Put a load on the motor, Checking the motor is capable of lifting that load.
So How can i fix the motor Characteristics and Start checking the capability of motor...Thanks for the last reply.
Post an example of what you want to input.
What Jim describes is what most people do. Input the motion they want and output the torque requirements.
This Curve I got it from motor specification. I want to Import this graph to the Motor Power or Speed-Torque. So that I can put the load and check whether this motor is capable of Lifting that load...Or Upto what level of Dynamic capability of this motor under operating.
Say for example if I am using this motor in 1st arm of Robotic ARM, Could the motor handle the end load, or which is the safer speed of operating the motor under the gravity...I want to simulate the exact motor capability in solidworks MOTION similar to real world. Thanks
How do you invision inputting these curves?
Lets say you can. What is the input to the motor to generate the motion? Base this on what you know motion can do.
What is the output from the software that you want or expect? Base this on what motion can do.
Make the problem really simple. 2 blocks with holes at one end. Mate them concentrically. Make one fixed and apply the motor to the other.
My opinion is you apply the motion you want and then check it against the graph. If it is above the graph at the speed you want, your design needs to change. It sounds like you want he software to compare the results against that graph automatically. That sounds like a cool feature but it doesn't exist.
Alternatively you could apply the toque or power and output the speed. If it is below the point on the curve (I Think...haven't thought it through fully), your motor isn't sufficient.
Yes.....I want he software to compare the results against that graph automatically..
Or in motion, when importing this graph, while simulating with a load , upto what position the motor can lift...It can show in physical...That will be good...
short answer, it isn't possible.
long answer, please review the thread, the method to do what you want to do has been described a couple of times. create the motion, output the results, check if it meets your curve. for your purpose you may need to do a couple of different runs to make sure it meets all your requirements.
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