I am thinking of doing another Webinar

[Peter Nachtwey]

I did one about 3 years ago using goto meeting.
I am thinking of doing one with Skype.
I am pretty sure that Skype will let me share my desktop with multiple users.I have no idea how many can view at a time though.

I am thinking of doing a test run with a test volunteer. I think I may be able to handle as many as 8 people but 4 or probably more like it.

Two topics that I can think of are
Second Order Plus Dead Time Temperature systems, PID tuning etc.
Estimating velocity and acceleration.

The webinars will be oriented toward those with a geek streak.

I have a very good SOPDT simulator now. I can change plant gains and time constants on-the-fly and the PID will adapt to the changing plant gains instantly.

Another recurring topic for us is an application where a customer simply wants to down load a position every 20 millisecond or so to our motion controller. How does one calculate the speed and acceleration?

 

[Gil47]

It is my understanding that only 2 people can do a video Skype link up, but an audio link up can involve multiple people link up.

I would be interested in knowing how to do a multiple video Skype link if you find it is possible.

Your subjects I also find to be of interest to me and I believe lots of others.

 

[Liam 28]

Hi Peter Im new to programming and Id like the chance to listen and watch in if its possible there two areas i have interset in . It would be great to hear another view on theses topics.

Billy

 

[danw]

You might find that GoToMeeting's experience has improved greatly in 3 years. I have.

My company subscribes to Gotomeeting. We get unlimited use for $275/month (I don't know if that is an 'annual rate')

We use it for a couple webinars per month, and twice a month sales training, so guys don't waste time driving into the office.

We also use for internal use; connecting to salesman's home offices and out-of-state offices. Joint conferences where documents need to be displayed.

More than once, I've logged on and had a customer log-in for the whatever time it takes for him to watch me go through punching the keys on a handheld communicator using a close focus web cam to view the communicator.

 

[Tom Jenkins]

I "presented" at a webinar a few months ago. I don't know all the software used, but we did tie into go to meeting and the presentation graphics were on PowerPoint. We had about 20 locations on line and about 5 people per location. The technical side went well, there wasn't much lag time, and all in all it went OK.

 

[Peter Nachtwey]

I think I should look into GotoMeeting

Actually, we use GotoMeeting a lot but I don't have a license.

 

[TurpoUrpo]

Could you also record those, so could be also watched afterwards?

 

[Peter Nachtwey]

Could you also record those, so could be also watched afterwards?

GotoMeeting permits this.

What other geeky topics would be of interest?

 

[rigicon]

Have a look at webEx Used that before for remote PC but the meetings look ok.
What I would really like to know discuss is chemical mixing at ratio.
I fixed a canon foam machine and the PLC program was very interesting. Simple 2 chemicals with a ratio say 1:2 and 2 frequency drives and a set time to deliver a set weight now control the flow - nice one closed tight PID control I think.

 

[leitmotif]

I did one about 3 years ago using goto meeting.

I am thinking of doing a test run with a test volunteer. I think I may be able to handle as many as 8 people but 4 or probably more like it.

Two topics that I can think of are
Second Order Plus Dead Time Temperature systems, PID tuning etc.
Estimating velocity and acceleration.

The webinars will be oriented toward those with a geek streak.

I have a very good SOPDT simulator now. I can change plant gains and time constants on-the-fly and the PID will adapt to the changing plant gains instantly.

Another recurring topic for us is an application where a customer simply wants to down load a position every 20 millisecond or so to our motion controller. How does one calculate the speed and acceleration?

Peter

I would like to participate.

The one thing I note here on this site is a very high tendancy to ignore basic mechanics and physics.

Since you are a guru at making stuff move and able to make estimates of how long how fast etc etc I suggest we stay in your expertise area and tap your brain.

I suggest as a model we use a project I am still pipe dreaming.

PROJECT convert 56 Chev pickup to electric drive. Motor will be 50 HP 230 3 phase 3600 RPM direct couple to differential input via drive shaft with either single or two shafts and universals. Power to motor using VFD supplied from 325 V 125 amp hour (estimated) battery.

Vehicle weight 5,000 lbs.
Tire RPM at 60mph is 900 (estimated)
Desired range between charges 50 to 75 miles.

I own the truck but right now it is not available to me. I can get hands on in a week or two to take actual measurements (weight, rolling torque using torque wrench on one wheel etc)

Will install Fluke data logger to record actual real time on road data. Will be interesting to compare computed values vs what I get in real world conditions. However this will not happen for a year. I realize there is no 5 minute and $5.00 project.

Things to calculate and estimate
1. Breakaway torque on hard asphalt vs concrete vs 6" snow and mud
2. Wind resistance and torque demand as result
3. Torque demand on flat vs on various grades up to 20%. Same set of calcs for power at various grades and speeds.

4. Acceleration time from dead stop to 60 mph in 10 mph increments.
5. Inertia at varying velocities
6. Inertia at varying velocities and on varying slopes downgrade ie will motor be an effective brake?

I can offer only three justifications for this project
1. Everyone has a car or truck. They are able to take the calculations here and dial in set for their vehicle and test it out on their equipment.
2. It is my project and I could sure use someone who does this every day.
3. I end up thinking they taught me this in physics 20 years ago - where is that dang physics book and finally are my numbers really right?

Dan Bentler

 

[ndzied1]

GotoMeeting permits this.

What other geeky topics would be of interest?

Depending on the time & date, I'm in.

Maybe these are more basic than you want to go but some ideas:

How about how to use RMS power calculations to select motors for hydraulic systems? Many many systems are made up of a low pressure/high flow phase followed by a high pressure/low flow phase. Sizing simply on the phase requiring the most HP will often oversize the electric motor.

Still many don't understand the flow vs. pressure drop characteristics of prop valves or how to calculate the pressure drop across a prop valve.

This isn't so much of a simple calculation but a discussion might be had on the topic of running a cylinder at rapid speed then hitting a hard stop that varries in position with a pressure limit. What are the best ways to keep the pressure spike down?

I'll keep thinking of more.

 

[Peter Nachtwey]

How about how to use RMS power calculations to select motors for hydraulic systems?

I have an example of that already. It was for test system for a helicopter nose wheel. The test was a sinusoidal test. If an accumulator was used the pump could be designed to provide 0.707 of peak flow but 0.75 of peak flow allowed for some leakage.

Many many systems are made up of a low pressure/high flow phase followed by a high pressure/low flow phase. Sizing simply on the phase requiring the most HP will often oversize the electric motor.

Are you assuming accumulators are used again?

Still many don't understand the flow vs. pressure drop characteristics of prop valves or how to calculate the pressure drop across a prop valve.

This is rather basic.
The pressure gain of the valve is misunderstood though.

This isn't so much of a simple calculation but a discussion might be had on the topic of running a cylinder at rapid speed then hitting a hard stop that varries in position with a pressure limit. What are the best ways to keep the pressure spike down?

does the controller know where the stop is? If not then the controller can only react to the pressure rise.

I don't think these would have a large audience. There would be you me and Alaric and that is about it.

I have a lot of hydraulic topics but I don't think many would be interested.

 

[ndzied1]

Are you assuming accumulators are used again?

No, Have a look at:
http://www.motorsanddrives.com/cowern/motorterms9.html

does the controller know where the stop is? If not then the controller can only react to the pressure rise.

Not exactly but there is a tolerance range. I'm thinking of some routine that starts a slow down at just above high side of the tolerance. (This is a real application for upset forming locking features onto fasteners) Further down the road would be an adaptive routine that tries to figure out where the material is and then move the slow down point. The idea being that a batch of the raw blanks should be at similar positions in within the tolerance.

 

[Peter Nachtwey]

No, Have a look at:
http://www.motorsanddrives.com/cowern/motorterms9.html

Good link. The topic is now been coverd.

Not exactly but there is a tolerance range. I'm thinking of some routine that starts a slow down at just above high side of the tolerance. (This is a real application for upset forming locking features onto fasteners) Further down the road would be an adaptive routine that tries to figure out where the material is and then move the slow down point. The idea being that a batch of the raw blanks should be at similar positions in within the tolerance.

In presses the key is to match the kinetic energy to the work that needs to be done when forming the piece. Extra kinetic energy results in pressure spikes. Not enough kinetic energy results in wasted type as the pressure builds up.

If this is not a press and the stop is sudden then the pressure will go up rapidly. The kinetic energy is converted to work. Work is force x distance. If the distance is small then the force is high. Since the area of the cylinder is fixed the pressure will be high. The best way to control the pressure spikes to do reduce the speed of impact. A good controller can see the rapidly changing rate shift the spool but often the spools don't shift fast enough. Another trick I like to use is an accumulator in the line between the valve and the cylinder. THIS IS NORMALLY A NO NO!!!! However, if you charge the very small accumulators to ABOVE system pressure they will not affect performance until there is a severe pressure spike and then the accumulator absorbs it but then returns the energy back to the system so the motion controllers PID doesn't see the loss of energy like it would with a relief valve. Relief valve don't work very well. They are slow and they don't have the ability to see the fast rise in pressure so they can relieve early in anticipation.

 

[Oakley]

How about recording it and posting it to a blog. That way it can be viewed at our leisure