Brainstorming for barbell/dumbell training logger - Page 1
Forum section: electronics / projects

author: con-f-use
author_rank: Unknown
timestamp: March 26, 2016, 01:02:43 pm
content: I'm in the very early planning stages for a new project of mine under the working titleWeightWatcher.The idea is to attach a little battery powered device to the end of a bar- or dumbbell that reads user tags and weight tags as the weigh plates slight over it.The device would then send the total weight, user id, its own id and a stream of accelerometer data to a receiver that logs the data and reception time.This way a strength athlete could easily create a training log or a gym might use the data for use statistics.I could use a little brain storming, if you want to help.So far I was thinking:RFID-tags for the weights? Barcode reading? Its probably enough to read the tags when putting plates on, since the last on is the first outBLE for transmitting the data but a low cost, low energy WLAN might be nicer since it doesn't require a special receiver station and has longer rangeDetection of whether the weight is but on or off might be done with two photo diodes or a hall sensorAttachment with an adhesive is probably more reliable than a strong magnet, seeing the plates will slide over the deviceAA(A) batteries will probably make the device to long, so LiPo and recharging via microUSB or be fancy and use Qi?Any better ideas? Suggestions for parts? Is it a bad idea? Better name for the project? Am I wasting my time since such a gadget already exists?

author: German_EE
author_rank: Super Contributor
timestamp: March 28, 2016, 07:47:02 pm
content: Having spent a considerable number of hours in a gym I would rather use either:a) A whiteboard containing my lift records along with those of my friends, nothing like a little healthy competition.orb) A cute trainer holding a clipboard and a pen, extra marks if she's a brunette or a redhead.Sorry but this really is a solution in search of a problem. The environment in a gym is remarkably hostile and whatever you build would need to be built to a similar standard as the rest of the equipment in there. An example, the last gym I attended had RFID chips in the towels to stop them getting stolen but in six months all of them failed as they didn't survive the washing process.

author: con-f-use
author_rank: Unknown
timestamp: March 29, 2016, 09:11:59 am
content: You are probably right, it's just another stupid fitness-gizmo that solves a problem no one has. I just want to build it anyway. Just for the fun of itAs a small defence, the system would probably log automatically with no user interaction apart from, "your plate has been scanned properly/scanning failed".And yes, it would have to be build very sturdily.The conceptually most difficult problem is, how do I detect the plates reliably?A ring-code in the hole would be a nice and cheap solution, if it wouldn't rub off quickly.Or a different number of magnets stickers close to the hole in the plate, e.g. 1 for 1.25kg, 2 for 2.5kg and s.o. (annoyingly they would come off all the time, I know).Quote from: German_EE on March 28, 2016, 07:47:02 pmNo logging application can compete with that. Actually no application can compete with that. But fortunately, you can't download women, nor can you order them for $20 shipped.

author: awallin
author_rank: Frequent Contributor
timestamp: March 29, 2016, 02:35:16 pm
content: for kettlebell lifting there's something called a "fixometer" (google or youtube will show some results).It's an accelerometer + uC + battery that sends data to an app on a smartphone/tablet/PC.useful for counting reps and learning to keep the weight still at the top - they say, haven't tried it...hardware is based on 'NODE'http://www.variableinc.com/#!node1/c1g5n

author: Maxlor
author_rank: Frequent Contributor
timestamp: March 29, 2016, 03:40:13 pm
content: Maybe instead of trying to detect the weights being put onto a rod, you could sense them being removed from their storage cradle. It should be much easier to come up with a mechanically solid sensing solution there.You could simply measure the weights by integrating a strain gauge into the rod.

author: technix
author_rank: Super Contributor
timestamp: March 29, 2016, 03:54:57 pm
content: If you can build your device into the bar itself this problem may be solved easier: you can use strain gauges or load cells to calculate the total weight of the bell after it is being lifted, bypassing the recording of adding or removing of weights.When your strain gauges register a significant peak, that means that your bell is being lifted, and the peak value maps to the weight of the bell.