Weight mat?

Hey guys!

Thanks for tuning in on my subject. 
I am a ABSOLUTE beginner in making robots but i am educated developer. That will hopefully help me a bit hehe.

I have a bit of a problem. I can not wake up in the morning. You probally know this issue: Alarm goes of, i turn it off and then.... ZZZzzzz. So to solove this problem i came up with an idea and i was hoping that you guys could help me with the details because i dont know what parts i can buy to make my idea reallity.

My idea:
I wish to create a alarmclock that will keep ringing until i am out of the bed and stays out of the bed for 15 or 30 minutes. 

The solution: 
As i see it, i will be needing to figure out how to messure the beds weight. Will it be possible to buy some kind of mat that is a weight? Another idea would be heat sensor but that sounds expensive and hard to figure out how to develop the software?

I hope you guys can inform me of my options to make this annoying alarm so that i once again can wake up and stay up :) 


Locate the turn OFF switch in another room. Perhaps connect wirelessly. However, whatever you can implement you can defeat. You can get load and or motion sensors with wiring and programming examples.

I did a project where i

I did a project where i canibalised a kitchen scales to weigh a cat. You could definately cut up a cheap bathroom scales to weigh a person (i wouldnt weigh the whole bed, but the mattress and person might work). I found cheapo kitchen/bathroom scales to be the cheapest way of getting hold of strain gauges, though you need to be aware of their max limit. Once you exceed the max limit they are ruined.

Or if you bought online, you could work out where they might fit on your bed mechanically, calculate the total weight range it needs to take, and buy the specific one you need.

You will need to look into how strain gauges work, and how to use amplifer chip (i used an IN125) to make the output useful



Another option: How about a PIR sensor? They only sense when movement is detected, so your alarm would go off, and wouldnt stop until it detected you moving. You could put the PIR somewhere where a wave from the bed wouldnt work?

Then have it switch, so once you have left the room/bed area, you cant come back in!



To forbid even an automayed

To forbid even an automayed way to deactivate alarm, insert a captcha to stop the alarm.

Another thought I had

Another thought I had besides using a weight mat would be to perhaps use an ultrasonic or array of ultrasonic sensors.  You could put them on each side of the bed, at the head or at the foot of the bed at varying heights.  Depending on how “thick” you are as you lay on the bed on your back, the alarm will know if you are in bed.  

You will have to make your bed each day or only make it pay attention with the ultrasonic sensors during morning hours.  Fun project!  Let us know how you make out.



one is enough

just one that looks for feet, just above ankle height, so it won’t be fooled with shoes. A typical cheap HC-SR04 has a range of 2m, which is enough.

Still not the solution

Thanks for the reply guys!

Im still not getting the super good idea yet. is there a way to scan the bed og have emitter and reciver to make a grid over a bed or just 2 single lines or something? i really need to find a way to make sure that noone is in the bed

Weight sensors

There are weight sensors you can get. i’ve not used them myself but my understanding is they are quite accurate. These would be the same type of sensors in a Wii Fit balance board for example. One on each leg of the bed should accomplish what you’re looking for. Similar to this: Weight Sensor

Thanks SmashleyIm concerned

Thanks Smashley

Im concerned about marks in the floor and the stabillity of the bed if i put those below each leg? I came across just what i needed just not what i needed. let me explain:

Would it be possible to use Weight sensor floor mat. 


Would any of these be able to messure the total weight og a bed?