discussion on interpreting robot sensor data - DAQ's PART 2

How much is a DAQ?

DAQ’s vary in price depending on manufacturer and specs. For example, the DAQ ADC11/12 by Pico was around $500aud from memory. This had 11 input channels, and was used in a UWA Mechatronic project testing forces on a walking frame (an ongoing student project). The DAQ’s from National Instrument were $800AUD minimum,

What connections are used with a DAQ?

There are a variety of connections, including USB, serial, PCMCIA, among others. If you are buying one with a new computer or laptop, I suggest USB for connectivity and portability.

NOTE: DO not go out an buy a DAQ, just to have a DAQ. If you want to know how to connect the DAQ to your robot/electronic device/ other electrical device then this will be posted next post.

How do I connect my robot/other electronic device to a DAQ?

This is not easy. It requires basic knowledge in circuitry and proficiency in soldering. As a result, I strongly recommend that if you have not got these skills or are under the age of 13, ask your mum, or preferably you dad, to do this for you.

First, look at the electronic circuit, and locate which are the output ports, and which ones are the inputs. (eg, the light sensor is the input and the connection from the light sensor is the output) Also locate which side the higher voltage is. Note this down on a printed diagram or on a piece of paper.

Second, get wires, and twist them into pairs. Solder one side of each pair at each of the outputs. This allows us to ‘read’ the information coming in.

Third, wire the twisted pairs into a parallel port/serial port/other port connector. For beginners, use a parallel port, and get a DAQ with a parallel port input. You can get these from RS components in Australia, or equivalent in your own country.

Fourth, plug your connector into your DAQ, and the DAQ into your computer.

Run the DAQ software.

How do I interpret the data coming from the DAQ software?

There are a number of ways to do this. Firstly, you need to know which sets of signals are coming from which sensor.

The numbers on the graphs, as your robot/ other device works is the sensor outputs. This means you can see when it fails, has problems, etc. you can then set new limits to stop your robot/other device from failing or running into problems.

There is another way to do this that is more visually appealing. There are programs such as Matlab, and national Instruments labview which allow you to write software that interfaces with the DAQ itself. There are a number of software that does this for you. I recommend Labview, but only because I have used it. There is a variety of different software that does this – go search for it.

well... that's all I can say about DAQ's. see you next week for more discussion about robotics.