GSR

Dear all,

I need to build a stepper motor control using MC3479 stepper motor driver. However, I don't know much about stepper motor and the stepper motor driver. I am not sure whether MC3479 is a standard stepper motor driver, but I hope my question are simple for everyone.

• If I tell the stepper motor to position A, do I need to keep the current even to keep the motor at that position? Or it will lock in that position? <===== the smiling face that I like the most
• If the load is too heavy and the motor cannot reach position A with one clk pulse to the stepper motor driver, what will happen?
• If I want to ask the motor to stay in a position, should I send a logic 0 to clk pulse?

I suggest:

Try to change were the power supply to the treadmill is connected. If your measurement is connect to the same powerline try to change it to another phase and wise verse. I suspect the you variable speed control for your treadmill... possibility to lots of overtones and high rather high in frequency too.

The noise itself like a lot of spikes + sine wave.

I connected an oscilloscope near the treadmill; and moved the probe from close to the treadmill to far away from treadmill (No one is on treadmill, but the treadmill is rolling at 3 mph). The noise goes down. This mislead me that the noise must not relate to powerline

I think you give me a good hint which the noise can also come from powerline for the constant speed control.

What is the bit resolution of the acquired data? Do you have enough resolution to resolve two signals 3 orders of magnitude different (at least 16 bit data is needed)? If so, can you post some of the data?

May I know how to resolve two signals? (They are in the same frequency band)

Dear all,

I need to record subject's neuromusclar activity (by surface electrodes) during he is walking on a TREADMILL. The treadmill create 180mv pk-pk noise; and the muscle activity is ~60uV. After the noise + signal passing through pre-amp, and 2nd order bandpass filters, the noise signal is dominant . Any idea how to overcome the problem??? I did try to put a little metal shield which is ground on the electrodes, but it did not help

Just started to work in a new location 2 months ago; and met a guy from another team a month ago.

Talked to him for 5 mins the 1st time. In the following week, he looked for me everyday to help him get into our building. I understood he did not have the latest key card, so I helped him for a week

In the last 3 weeks, he almost came to my office everyday, and talked about stupid thing. Even me and my teammate were talking something important, we would just come and join. I was starting unhappy with this type of behavior.

In the last weekend, I was building a circuit in my office. He came again, I told him that " I am sorry I am very busy today and have not time to talk to you, how if we talk in the other day? " He said ok and left. 5 mins later, he came back, and told me " your boss is here today at his office" I was very unhappy and asked "what did you say?" And he know he should let me alone, so he said not to bother me.

Today, we met each other face to face, I thought we would say Hi at least. But he did not even look at me. I felt bad, I felt I did something wrong.

Have you ever met anyone like this?? What will you do?

To be hornest, they make me feel very unhappy.

Should I just contact the sale support and ask for their sale manager to reply?

I really want to get something back from Mathworks:shifty:. Our lab spends money to buy many toolboxes from them, but they mess-up our stuff:(. Do you think I can ask for free online training:lol:? I want to learn stateflow:D or even more. Or I want to get so-called the icon of Matlab hero, the matlab t-shirts for everyone in my lab:D.

Try their website.

But I could not find any number or email address that can be used for complaints

I am so unhappy that I need to submit a paper by the end of this month. Yes this month Aug31, 2009. However, I still have not gotten their toolboxes .

I submit a order, the mathworks sale representative (Mrs. R) is having 4 month vacation. She asks our purchase department to contact another mathworks sale representative ("Mr. T"), who was also out of office for ~ a month. I called mathworks hotline, they ask me to send the purchase order to info@mathworks.com. My purchase department did that, but did not get any feedback. Two to three weeks later, I was finally able to contact Mr.T, he said he needed my purchase department to send him another PO because he won't get the email from info@mathworks.com and he had never received any PO form my purchase department. OK! My purchase department send the PO to Mr T; and I received the notice from my purchase department. At the same time, I also forwarded the notice to Mr. T. I called Mr. T. :wacko:Three days later, he said he did not receive anything again. I told him I forwarded the notice to him; and he found from his email box and figure out I did email him the notice:angry:.Mr T is a axx-hole and ignored all my purchase department and my email:frusty:.He told me that the quote was expired, but he would still try to submit the order. (But who make the 1 month quote expired????? )

I really want to contact his head to complaint the issue.

Who should I contact to? Any email address or phone number??

Dear all,

I use simple opamp a lot. Recently. I use an AD620 biomedical bipolar opamp as a preamp for EMG circuit. I found out that there is a reference connection, what is the reason for a bipolar amplifier having a reference connection??? Could you please give me some idea?

Please ignore, find solution. Thanks for reading this topic

Dear all,

I use simple opamp a lot. Recently. I use an AD620 biomedical bipolar opamp as a preamp for EMG circuit. I found out that there is a reference connection, what is the reason for a bipolar amplifier having a reference connection??? Could you please give me some idea?

If I have an equation

y(t) = a1x1(t) +....+a9x9(t)+nonlinear factor+noise

want to do linear regression

any different between sample rate is 100Hz and 1000Hz? Assume 100>>nyquist frequency

Will the fitting be better at 100Hz because of the variable to sample rate ratio is higher at 100Hz??

BTW, what is this icon mean:ph34r: <========????

May I know what is the benefit to become alliance member??

{signal - mean(signal) }/std(signal) ???

I am not sure the name , I think it is used in Z stat or F stat.

What quality measure do you want to apply? Zero control error, fast response?

Zero control error

Dear all,

This question may not related to LabVIEW, but I think I can ask here because the LAVA lounge should allow to talk anything . I am doing a Simulink control system project (See pic). A and B are the input, C is the recorded output data. If the model is prefect, the scope should give a zero reading.

I have 6 parameters that I need to tune. I can use my knowledge of the system to have initial values, but 6 parameters tuning is too difficult for a new babie . Does any function in Simulink, Matlab or LabVIEW handle this type of problem??

Thanks

The spherical bearing prevent the propagation of bending. If the load cell is bended the spring is subjected to coupound sollication it is bad for the precision.( and it can damage the cell )

in other world You must have an idea of the sollicitations. What are the component of the screwer ( torseur ) on the cell?

Some numerical value could be interesting.

Thanks for your suggestion

However, on the other hand, do you think this prevent bending feature affect the reading??

But there are situations where such parallel (to load cell) connection makes sense. For example you expect very high forces, but the sensor has very small range. With inter-connection sensor feels only a part of total force and the factor (F_sensor/F_total) is equal to k_s/(k_s+k_i), where k_s and k_i are stiffnesses of sensor and inter-connection respectively. Typically any inter-connection will has much much higher stiffness than any sensor and consequently force felt by sensor will be below its sensitivity. But when k_s and k_i become comparable it may be usable.

My situation is having 500lb load cell to measure the force that in between 0 - 250lb. I understand what you say. Your idea is like the potential divider in Electrical term. I really have no clue why my boss and his friends consider that is right . The biggest problem is the compression and tension forces have different offsets and gain value because of the "Middle sturture" bypass part of those forces. Moreover, how tight the screws will also change the gain of the reading and the "Middle sturture" also creates an idle region. My understand is that the output is Y = G1*compress if compress > theshold1 and Y = G2*tension if tension < thershold2. Those thersholds can be changed by turning those screws.

Think of load cell as of a spring. Measuring the force is nothing more than measuring deformation of the spring in some way. If spring is not allowed to be deformed you will not measure anything. So when you have a mechanical chain and want to measure force between its two parts, you have to cut the chain in this point and put load cell between connecting INDEPENDENTLY both sides of a cell to respective parts of a chain.

I agree with what you said . Exactly what I am thinking, the load cell is not connected independently to those two metal pieces because of the inter-connection of those screw and silver disk

The short one is use some

http://www.skf.com/p...&newlink=3_3_11

The biggest problem is that I am not the designer and I don't have the CAD drawing.

I should not be lazy and I should use make a drawing using pencil

BTW, I only understand English. Do you have English version of the above link? Thanks

Dear all,

I need some suggestions of this mechanical design (I understand it is not related to LabVIEW , but this is the last step before LabVIEW, please help ). I think there are some problems.

The idea is to use load cell to measure the tension and compression force across two metal structures. The load cell gives a linear reading for compression and tension, the structure in between should not affect the reading

The support frame is designed to prevent twisted force act on the load cell

One of the load cell hole is a tap hole, the other one is a REGULAR hole

Please give some ideas, do you think the structure in between does not affect the reading??

Dear all,

Could someone please share the experience? I have submit more than 1000, and I only get one face to face interview. On the other hand, If you are a boss, how would you think of a person study for long time and without industrial experience? Moreover, how would you think about a person only have a temporary status to work even if he claims that he does not need sponsorship and will get green card ?

Thanks

QUOTE (Dan DeFriese @ Mar 18 2009, 11:45 AM)

Microsoft has certifications out the wazoo http://www.microsoft.com/learning/mcp/default.mspx#CERT. They have freely downloadable "Express" Editions of all their Visual Studio development tools (Visual C++, Visual Basic, etc...). Just browse around the Microsoft.com and msdn.com websites.

Thanks

QUOTE (Louis Manfredi @ Mar 17 2009, 09:30 PM)

Really thanks so much that you are willing to type so long to tell me so much information and suggestion :worship:

QUOTE (Cat @ Mar 17 2009, 06:18 PM)

Now this is an interesting question. I find that if I'm going to abbreviate it, I say GUI (gooey), but if I'm going to say it all out, I say "User Interface". So I personally would not say UI (you-eye) or "graphical user interface".

Most of the folks I program with are C programmers and wouldn't know a GUI if one smacked them upside the head, no matter how I pronounce it. :-)

Cat (42/1000! Well on my way!)

I say (gooey) to indicate the user interface for the last 3 years :laugh:

QUOTE (Gary Rubin @ Mar 17 2009, 06:51 PM)

Right!

I don't understand what the company is because only an agent talk to me. He just told me there is a position and ask me to finish the exercise. Anyway, I start to find out whether Microsoft offers any C++ certification exam. (I am a lazy person, so I need an exam to force myself to learn)

Dear all,

I understand this is not relate to LabVIEW, but relate to me (a LabVIEWer). Is there any C++ certification by Microsoft?

Thanks

QUOTE (Cat @ Mar 17 2009, 01:05 PM)

Substitute "C++ programmer" for "LV programmer" and ask the question again. Your analogy implies that LabVIEW is a specialized language. Or maybe isn't really a language at all, but a tool for some specialized purpose. That may have been the case back in the Bad Ole Days, but some of us use it for a general purpose programming language. Yes, I can control instruments with it. Yes, I can automate tests with it. But over the years I've used it for a lot more than that.

So as some other folks have said, if you're hunting for a job, it's important to know exactly what you're applying for, and just like with any other language it's important to know your particular strengths and weaknesses.

Good luck with the job hunt!

Cat

Thanks for your suggestion

I just start with a bad luck day. I received an email about a software engineer position an hour ago, they send me an exercise and need me to finish it. The exercise include a short Matlab, a short C programming problems and a long C++ problem. I spend 2 mins to solve the Matlab and C problems. However, I have never programming C++ in my life. I just feel myself a piece of shit. Why did I learn java not C++. I still try to solve it, but they are asking "automated unit tests" which I never never heard. OHHHHH, lost another chance to have a job.

QUOTE (shoneill @ Mar 17 2009, 08:06 AM)

Thanks for reminding me. I thought GUI is the standard term . When I was living in foreign country, I wrote American addresses, I used "U.S.A." as the country. However, I found out that American wrote their country as "U.S." after I have been here for years. I used to use the Matlab version "UI" which is GUI, so I am sorry that I asked the stupid question. :laugh:

Btw, how will you pronounce UI?? Do you just call it U-I or call the long form user interface?

First, Thanks for everyone to answer me the question

As my first non-academic interview, I did a very poor preparation.

I was asked to prepare a presentation 2 days before the interview; and I know the exact date for interview as the same time. Too many things need to be done before a few hours of driving to the interview.

I had prepared the interview for a week, but I went to a wrong direction!

• Spend a few days for preparing the 200 standard questions: e.g. what is your weakness??
  

• Spend a day to understand the company. However, I really misunderstood the position until I asked the manager a question during the interview: How would you describe a typical day in this position? I thought it was a R&D position in a team, but it is a one-man-team position including customer service.
  

• I was so stupid that I did not read the undergrad. book, refresh my old knowledge.
  
• I was so stupid that I did not ask about this question "What knowledge other than LV should you know if you are a LV programmer" in this forum
  

Anyway, good experience! I know much more about the industrial interview

BTW, could anyone please tell me more about What is UI? and anything about Noise reduction techniques? thanks :worship:

After I fail in my LV job interview, I really want to know what knowledge should a LV programmer should know? I understand that the answer may depend on the company, but any general knowledge that I should know?

Maybe I should give an example, I would expect a webpage developer knows about Photoshop, Dreamwaver, php, frontpage, etc