Loadcell / strain gauge amp connection
Step 1: Let’s first connect the Load Cell to the Strain Gauge Amp
Materials:
1 x 4 Position Rectangular Housing Connector (vendor: Digi-key Instruments, part no: WM1722-ND)
1 x 14 Position Rectangular Housing Connector (vendor: Digi-key, part no: WM17001-ND)
14 x 26-28 AWG Crimp (vendor: Sunrise Instruments, part no: WM2023-ND)
1 x Loadcell (vendor: Sunrise Instruments, part no: 3564F)
1 x Strain Gauge Amplifier (vendor: Dephy, part no: 6ch)
1 x Surface Mount (vendor: Digi-key, part no: WM7608CT-ND)
Tools:
1 x Crimping Tool by Molex (vendor: Digi-key, part no: WM15815-ND)
1 x Wire cutter
Instructions:
1) Cut 11 cm of black loadcell cable using a wire cutter
2) Strip 4 cm off of the insulation of the black load cell cable
3) Take wire off
4) Match input and output channels of the loadcell to those of the strain gauge amp.
Refer to the schematics below:
- Schematic for the loadcell
- Schematic for the strain gauge amp
- Connection table (Explains how to connect the loadcell to the strain gauge amp)
5) Put 26-28 AWG crimp to all ends of the loadcell cable using the crimping tool.
Refer to the crimping video below if you have not used the crimping tool before:
6) Insert the crimped wire into the housing connectors:
For the 4pins connector in the strain gauge amplifier, we used 4 Position Rectangular Housing Connector and 26-28 AWG Crimp.
For the 14pins connector in the strain gauge amplifier, we used 14 Position Rectangular Housing Connector and 26-28 AWG Crimp.
7) Insert the housing connectors into their corresponding surface mounts in the strain gauge amp.
Step 2 – Let’s connect the Strain Gauge Amp to the Motor
Materials:
(*Materials in the pictures are listed from top to bottom and then left to right.)
1 x 10ft. 26AWG wire (vendor: McMaster, part no: 2674N21)
1 x Shrink wrap
1 x 20 Position Rectangular Housing Connector
1 x 6 Position Rectangular Housing Connector
6 x 26-28 AWG Crimp (vendor: Sunrise Instruments, part no: WM2023-ND)
6 x 28-32 AWG Crimp (vendor: Sunrise Instruments, part no: WM3670TR-ND )
Tools:
1 x Wire cutter
1 x Crimping tool
1 x Hot glue
1 x Heat gun
Instructions:
1) Cut 4 wires (26AWG) to 30cm each
2) Expose 1mm wire from both ends.
3) Put 26-28AWG crimp on one end of all the wires using the crimping tool (these will be used to connect to the strain gauge amp)
Refer to the crimping video below if you have not used the crimping tool before:
4) Put 28-32AWG crimp on the other end of all the wires using the crimping tool (these will be used to connect to the motor)
5) Place the wires with the 26-28AWG crimp to 4 Position Rectangular Housing Connector
Refer to the schematic below:
6) Now we will separate the wires into 2 groups and place shrink wrap to cover all exposed wire
Group 1: Put side with 28-32AWG crimp to 20 Position Rectangular Housing Connector (these will be used to connect to the motor)
Refer to the motor schematics below:
Group 2 (i2c, SCL): Put side with 28-32AWG crimp to 6 Position Rectangular Housing Connector
Refer to the motor schematics again:
7) Use hot glue at the intersection of crimps with the housing
8) Repeat for all housings
9) Use heat gun to shrink the shrink wraps
10) Plug all the cables to their corresponding housings of the motor
Refer to the schematic called “Harness”:
Step 3: Finally let’s connect the Load Cell to the Knee
Materials:
1 x p002_pyramid
1 x p1016_distalBase
1 x loadcell (vendor: sri, part no: M3564F)
3 x M5_10mm_low (vendor: McMaster, part no: 93070A121)
6 x M5_12mm (vendor: McMaster, part no: 93395A304)
4 x M3_8mm_low (vendor: McMaster, part no: 92855A309)
Tools:
1 x 2 mm allen
1 x 2.5 mm allen
Instructions:
First connect pyramid to the loadcell using 3 x M5_10mm_low screws using a 2.5mm allen to get the configuration below:
Then connect the loadcell to the distalbase using 6 x M5_12mm using 2mm allen to get the configuration below:
Finally, flip the assembly and connect it to the knee using 4 x M3_8mm_low screws using a 2.5mm allen to get the configuration below.
