Wiring

 

8

***For higher quality images, download the supplementary guide in document form: MantisBot Supplementary Guide

Each red line represents a double (positive/negative) wire for conducting power to each leg. These connections are made with 8 AWG marine wire, stepped down to 12 AWG wire, then ultimately to barrel jacks for being plugged into the Arbotix-M and power hubs. Black lines represent three-wire TTL connections that carry power and signal to servos. Green lines represent 3-wire 26 AWG connections that interface with pin headers to carry analog readings from strain gage circuitry to the Arbotix-M board. Blue lines represent 2-wire 26 AWG connections that allow the strain gages themselves to be wired into the analog circuits on the perfboard. Not labeled here is the USB/FTDI cable that connects the Arbotix-M control board to the PC running AnimatLab. It is important that this is plugged into the board in the correct direction. The “GRN” and “BLK” labels on the board should correspond with the green and black wire ends of the FTDI connector respectively.

9

 

Wiring for strain gage integration is done with two- and three-wire custom cables made of green 26 AWG. Two-wire cables are used to connect the gages to the circuit via the two-pin pin headers on the pieces and on the perfboard (yellow arrow). The orientation does not matter since strain gages (as resistors) are bi-directional. The three-wire cables connect the circuit to the Arbotix-M board. Orientation matters for these connections, as the three wires (from left to right as shown) represent signal, 5V, and GND. The signal pin is always the one closest to the op amp on the perfboard (purple arrow) and the most inward on the Arbotix-M. On the wires currently used for MantisBot, the signal wire is marked with blue marker near the end of each end of each cable. I highly advise keeping cables labeled in this way, as well as with which leg they are for (LH = left-hind, RF = right-front, etc.).

When combining multiple shorter 3-wire TTL cables to make longer single cables, be very careful to keep the wires organized so that the proper ones are mated. The following diagram may be helpful:

10