What’s inside your Mindsensors GlideWheel-M

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My Mindsensors GlideWheel-M decided to die on me at a most in convenient time whilst building the Mark II version of my Bin Emptying Robot. I was forced to use limit switches instead. After talking to Deepak Patil from Mindsensors, he suggested I take a knife in hand and disassemble it. The process was straight forwad enough, provided you kept the blade to the edge of the sensor. You are restricted to around 5mm at the sensors edge. Go any further in and you risk damaging the electronic components.

MindsensorsGlideWheelM-03.jpg

Both Deepak and I was hoping that the issue with my [GlideWheel-M] was a fractured joint on the NXT Cable mount on the PCB end. I tried re-soldering the joints which unfortunately didn’t solve the issue. The continuity between the NXT Plug and the [GlideWheel-M] checked out to be fine. As it is the [GlideWheel-M]’s Tacho/Rotation Sensor part works fine. But when it comes to powering the [lpfm] or [spfm] Motors it fails.

 

GlideWheel-M -Internals.jpg

The [GlideWheel-M]’s Internals is an optomechanical arrangement, with a disk that moves mechanically, and an optical system counts pulses of light.This arrangement is what is used in the older ‘Computer Mice‘ that use a ‘Ball’ that drives a disk with slots in it which allows light to pass through.

GlideWheel-M - Internals - 2.jpg

On either side of the disk there is an infrared LED and an infrared sensor. The holes in the disk break the beam of light reflected from the LED so that the infrared sensor sees pulses of light. The rate of the pulsing is directly related to the speed of the motor and the motor’s Encoder Count. This is called rotary encoder, also called a shaft encoder, “an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital code”. Rotary encoders are used in many applications that require precise shaft position including industrial controls, robotics, computer input devices, such as optomechanical mice and trackballs as mentioned previously.

So after this attempt at retrieving my GlideWheel-M from the grave, I guess I’ll just have to get a replacement….

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