Disassembling the HiTechnic Force Sensor - it is an FSR

Its been a while since I saw the HiTechnic Force sensor for LEGO.
What intrigued me is that it seemed to be solid state sorce sensor, which means that there are no moving parts.
This is why I decided to buy one, and take it apart. Here are the findings:


Here is how the HiTechnic Force Sensor looks like.


Its impossible to open the force sensor without damaging the cover.
This image shows how the white cover was separated.


Once the top white cover is removed, then the black and gray parts of the sensor body can be separated.
As these parts slide, the internals of the sensor becomes visible.


Once the sensor is open, the sensing element becomes visible.
The round part on the flexible PCB is the Force Sensitive Resistor (FSR).


Another view of the FSR.


Photos of the PCB - for the record.


Photos of the PCB - for the record.

It is clear that the engineering of the sensor is quite neat. For example the pin which is used to transmit forces from outside onto the FSR (seen on the forth picture on the left) was designed to reduce friction.
Nevertheless, the usability of this sensor would be quite limited for a two main of reasons. First, the known problems of the FSR technology where the sensing technology is not accurate and repeatability is low. Second, the friction between the pin and the body will reduce the measurement accuracy and probably result in hysteresis.

To summarize: I am not impressed.

Copyright (c) 2009