I finally received enough parts to assemble the load cell signal conditioning circuit board.

The circuit schematic and PCB layout for load cell signal conditioning were covered in a previous blog.

The TE Connectivity FX1901 load cellFX1901 load cell will be used to measure the amount of fluid in the Graffitibot reservoir by weighing it.

It isn't clear which variant of load cell (in terms of full scale output) I have, so I will have to hook it up and see what the output looks like.

Also I am not quite sure how to mount the load cell - there are no obvious mounting fasteners, so I will have to test how it responds to force on various surfaces.

Here is what the circuit looks like in action:

The signals take some time to settle down because I have a pretty severe low-pass filter on the signal - to minimize fluctuations due to fluid sloshing around.

The output voltage is slightly negative with no load - this is okay because the weight of the empty reservoir with motors in it will bring the signal above zero.

This is a good start to getting the custom PCBs working.

The next sensor will be the magnetic angle sensor.

 

 

Relevant Links

Sixth Sense Design Challenge: About This Challenge

Sixth Sense Design Challenge: Technical Documents

Sixth Sense Design Challenge

 

GraffitiBot Project Blogs

Sixth Sense GraffitiBot - blog 1

Sixth Sense - Kit Unboxing and Other Parts - GraffitiBot blog 2

Sixth Sense - Sensor Circuits - GraffitiBot blog 3

Sixth Sense - Interfaces - GraffitiBot blog 4

Sixth Sense GraffitiBot - System Interconnect - blog 5

Sixth Sense GraffitiBot - Wheels & Motors - blog 6

Sixth Sense GraffitiBot - ST Sensor Tile App - blog 7

Sixth Sense - Load Cell PCB - GraffitiBot blog 8

Sixth Sense - Magnetic Angle Sensor - GraffitiBot - Blog 9

Sixth Sense - LCD Interface - GraffitiBot - blog 10

Sixth Sense - Pump Controller - GraffitiBot Blog 11

Sixth Sense Main Drive Motor - GraffitiBot - blog 12

Sixth Sense Motor Controller Mods - GraffitiBot blog 13

Sixth Sense - RTD - GraffitiBot Blog 14

Sixth Sense Mechanical Design - GraffitiBot Blog 15

Sixth Sense GraffitiBot Motor Wiring - Blog 16

Sixthe Sense GarffitiBot - First Dry Run - Blog17

Sixth Sense GraffitiBot Hydraulics - Blog 18

Sixth Sense GraffitiBot Printing Graffiti - Blog 19

Sixth Sense GraffitiBot - Summary - Blog 20