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    #16
    Originally posted by doctor ed View Post
    To my naive eye, the Leonardo board looks like it could do the necessary?

    Then there's this:
    https://www.adafruit.com/product/1272

    That with a Leonardo board and the hardware is looking sorted?
    Yeah that should do it, looks like the Leo has 12 analog inputs. I think Uno Shields plug into the mega too as you could get even more capability with a bit of code tweaking if you had to.

    Comment


      #17
      The gps logger board doesn't seem to be mega compatible, so the Leo would be the best option.

      That said, apparently the inductive speed sensors aren't read very reliably. Hall effect is ok, but he induction types are a bit of a dud.
      Mit freundlichen Gre

      Originally posted by Keith Duckworth
      "I think that in a racing engine, the closer it is to disintegrating, in general the better its performance will be "

      Comment


        #18
        Awesome stuff, I've been thinking about looking into these recently. Looking forward to more updates.

        Comment


          #19
          Modified to use the Mega:

          http://www.instructables.com/id/Pers...ate-GPS-Shiel/

          And another mega modification:

          http://www.instructables.com/id/Ardu...nd-SD-Logging/

          Idiots guide:

          https://learn.sparkfun.com/tutorials...d-hookup-guide
          Mit freundlichen Gre

          Originally posted by Keith Duckworth
          "I think that in a racing engine, the closer it is to disintegrating, in general the better its performance will be "

          Comment


            #20
            I've done a fair bit of Arduino logging, including that adafruit board since 08. How many times per minute do you plan to write this data? SD card is going to be your bottleneck and also the first thing to fail. Buy a good one.

            Comment


              #21
              How fast is a reasonable log rate for these things? I would've thought logging at 10Hz for durations of maximum 30mins would get me in the ballpark.

              That's 18,000 log points in 30mins, with say:
              Gps lat/long/speed
              3axis X Y Z
              4x suspension position

              So 180,000 data points in CSV format
              Mit freundlichen Gre

              Originally posted by Keith Duckworth
              "I think that in a racing engine, the closer it is to disintegrating, in general the better its performance will be "

              Comment


                #22
                10 hz will be fine, and that is not even kb/s so quite OK for a cheap SD.
                Jason Broadhurst

                Someone once asked me if they could use my mower. I said "sure, so long as it doesn't leave my yard"

                Comment


                  #23
                  The latency is in opening the file, writing, saving, releasing file handle. I haven't looked at that shield's library since pre Arduino 1.0 days, but back then you had to do that full sequence for every write. If that's still a limitation you'll need to batch writes.

                  Comment


                    #24
                    Originally posted by aerobrick View Post
                    The latency is in opening the file, writing, saving, releasing file handle. I haven't looked at that shield's library since pre Arduino 1.0 days, but back then you had to do that full sequence for every write. If that's still a limitation you'll need to batch writes.
                    from memory when I was using it the program logged "10 entries", then opened the file, saved the data and closed the file, maybe it just saved every 10 logs. I think I made it save every time it logged as my sample rate was low (one hert) and I didn't want to lose any data points.

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                      #25
                      Was broadly looking good at software interfaces that could be used to crunch these data dumps, and landed by gems (apparently their software gets a great wrap, along with motecs). In any case, they also have thus...

                      http://www.gems.co.uk/docLib.php?doc...cification.pdf

                      Still trying to find a price on it, but 'looks' inexpensive. Need to look at viability of plugging in a GPS to the serial port, and then what dactyl would be needed to get CAN data, but it would suddenly become a very viable solution
                      Mit freundlichen Gre

                      Originally posted by Keith Duckworth
                      "I think that in a racing engine, the closer it is to disintegrating, in general the better its performance will be "

                      Comment


                        #26
                        Hi Ed,

                        Thanks for your email.

                        Yes, we can sell you one directly...prices follow.

                        DA3 - 860
                        Shipping - 35

                        Our data analysis software 'lite' version is free of charge and can be
                        downloaded from our website here
                        http://www.gems.co.uk/?content=pages...ware-downloads We also have a
                        'Pro' version which has added features such as maths channels and CSV
                        import/export...details of the differences can be found here
                        http://www.gems.co.uk/?content=pages...-data-analysis The pro version
                        costs 250

                        If you wish to go ahead with the purchase, I will require your full contact
                        details...address, telephone and VAT number if you have one. I can then set
                        you up on our system and send you our pro forma invoice. Goods can be
                        shipped upon receipt of payment which can either be made by bank transfer or
                        credit card.

                        Best regards

                        Pat Simpson
                        GEMS Ltd
                        Mit freundlichen Gre

                        Originally posted by Keith Duckworth
                        "I think that in a racing engine, the closer it is to disintegrating, in general the better its performance will be "

                        Comment


                          #27
                          Originally posted by doctor ed View Post
                          How fast is a reasonable log rate for these things? I would've thought logging at 10Hz for durations of maximum 30mins would get me in the ballpark.

                          That's 18,000 log points in 30mins, with say:
                          Gps lat/long/speed
                          3axis X Y Z
                          4x suspension position

                          So 180,000 data points in CSV format
                          10Hz is no good for suspension position. 270 kmh is 75 m/sec so 10Hz at 75 m/sec is a suspension travel reading every 7.5 m of travel. Scale accordingly for slower speeds. Barely useful.

                          Comment


                            #28
                            So at 280kmh Im only getting a datapoint every 7.5m, which is still every 0.1sec

                            If I do 100Hz sampling, what info suddenly becomes apparent? Does meaningful, tunable suspension movement occur under 0.1sec intervals? i can see that more resolution would be good, but wheres the line between enough and too much?
                            Mit freundlichen Gre

                            Originally posted by Keith Duckworth
                            "I think that in a racing engine, the closer it is to disintegrating, in general the better its performance will be "

                            Comment


                              #29
                              Buy an old generation AIM Mychron MXL and AIM do patch harnesses that logs every sensor in the car.

                              Comment


                                #30
                                Originally posted by doctor ed View Post
                                So at 280kmh Im only getting a datapoint every 7.5m, which is still every 0.1sec

                                If I do 100Hz sampling, what info suddenly becomes apparent? Does meaningful, tunable suspension movement occur under 0.1sec intervals? i can see that more resolution would be good, but wheres the line between enough and too much?
                                without thinking about it too much a reading every 7.5 metres (actually 7.778m) would probably be OK if it was an averaged reading, but consider the following:

                                going around two corners, identical in every way but one is flat and one is bumpy.

                                On the smooth corner you will have readings that correspond to the compression/extension of each corner at X intervals. (if your main logging environment is smoothish racetracks this is probably fine)

                                On the bumpy corner you will have readings that correspond to a combination of the compression/extension of each corner plus whatever the bumps and holes are doing to the corners are doing at the same interval.

                                It will be pretty trivial to adjust the sample rate and the files will be pretty small so it probably isn't worth worrying about too much. Better to have too much data than not enough, but I think you will be limited by either the program or storage requirements, and you will spot an oversampled graph pretty quickly and be able to adjust accordingly.

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