Designing a simple DC Massage device

[dr pepper]

Looks Ok, might work.
I'm not aware of arduino boards with hardware power switches.
That kinda thing commercially would be done with power saving techniques such as sleep mode, where the 'duino is still powered up but draws very little, making the battery last for pretty much its shelf life.
You'd still probably need a power switch for the motor though, as I'm guessing with no Pwm input and the motor stopped the motor electronics will still burn some juice.

 

[crowtor]

So I decided to use an IR temp sensor instead of mounting a thermistor, since it's a vibration motor and mounting something permamently could be an issue. I chose this one:

https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+SheetTS318-11C55ApdfEnglishENG_DS_TS318-11C55_A.pdfG-TPCO-032

I can point it at the housing or at the shaft, does it matter where?

 

[dr pepper]

That would work, however you'd need some fairly complex signal processing to get the 'duino to read it.
I suggest one of these:

Gy-906 Mlx90614 Non-contact Infrared Temperature IIC Sensor Module Mlx90614esf for sale online | eBay

Find many great new & used options and get the best deals for Gy-906 Mlx90614 Non-contact Infrared Temperature IIC Sensor Module Mlx90614esf at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

And it has a library available for the 'duino:

GitHub - adafruit/Adafruit-MLX90614-Library: Arduino library for the MLX90614 sensors in the Adafruit shop

Arduino library for the MLX90614 sensors in the Adafruit shop - adafruit/Adafruit-MLX90614-Library

github.com

I've never used one so I odnt know how easy they are to use or how good they are.
Looks like it can read the ambient and target temp.
You could run the motor for a while, use the sensor to see where is the warmest then use that as your target area.

 

[crowtor]

Thanks alot dr pepper , that really simplifies things. Here's what the semi final product looks like:

I had some difficulty fitting the MLX90614 behind the motor, I thought I'd separate the sensor from the board, put the board in the handle with the batteries and leave just the sensor inside the motor housing, no luck. It would be easier If I could find a flexible tube that had a groove or some king of fixture.

 

[dr pepper]

Looks like your going to 3d print that, proper job.
You could always revert to a more conventional temp sensor like a ds18b20, theres a high probability that the temp of the motor will be fairly even, its not that the motor is subject to rapidly changing dynamic loads or supply power / direction changes like a servo, its just whizzing a weight around.
Heres a wacky idea, use the yellow rpm feedback wire to tell the 'duino how fast the motor is turning, and use that to calc the vibtation level, and further use that to scale the pot command value, so that turning the pot gradually increases vibration over its rotation, instead of the last bit making the biggest chage.
Glad to be of help.