Combination Report Einstein Robot



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Figure 2-3: Mask Fully Attached

It was also decided to replace all of the terminators with 'industry standard' Futaba style connectors. The existing single-plug per wire was an error-prone setup which could cause servo malfunction and harm if the wires were improperly connected (a very high probability given the number of connectors) and they were most likely more prone to malfunction as the connectors would be less supported and more prone to bending pins and pulling free.


The standard connector has a single three-contact female plug which allows for signal, power, and ground pins to be connected with one shell. The plug can still be reversed but this will not typically result in any error for the controller or the servo. The power conductor is located in the middle of the three conductors so a reversal will connect the power where it belongs, the ground will be connected to the pulse-width-modulation input of the servo (causing no harm, the servo will simply not see any PWM signal) and the PWM output signal from the controller will be connected to the servo ground pin (which is not hooked to the controller ground because that was hooked to the PWM signal). So no harm typically comes from such a reversal.
Some of the servos had the wires simply cut, presumably to 'steal' the connector for another system and there were two servos that did not function when tested. It was interesting to note that both non-working servos were of the same type (Hitec HS-300) which perhaps had a design flaw which caused failure or perhaps someone had hooked them up incorrectly since the plugs were all individual and a reversal of power and ground could damage the servo beyond repair.
Many of the servo wires had to be lengthened or replaced to make them reach and all be stranded. This was done by purchasing 12 inch servo extension cables and splicing them on to the existing servo wires to make them flexible, long enough to reach, and with standard connectors at the ends. There were several servos left which had only slightly short wires which were lengthened with shorter servo extender cables.
The cables were routed to the best connector on the controllers where the wires would route best and the bundles were zip-tied together to keep them from interfering or getting caught in any of the rotation pinch-points of the neck.
Several of the servo attachments which had been made of wire had poor bends making them bind or bend easily. The solution was to use 'piano wire' or 'music wire' which is partially tempered mild steel so that it very similar to 'spring steel'. This steel wire is incredibly tough and resistant to changes in shape as it tends to spring back into shape unless bent too far. Unfortunately, this also makes it incredibly hard to bend properly for servo connectors. This difficulty is mostly overcome using a bench vise in conjunction with very heavy-duty needle nose pliers and being careful not to get pinched if the pliers slip.
The main portion of the rod needs to be nice and straight, never having been bent. This will give it the most rigidity and spring-back if it is forced out of straight. The terminations where the wire passes through the servo horns and control surfaces needs to be nearly a right-angle (but not too sharp or the wire may crack). The bend-back after the pass-through needs to be similar. The shape of the wire is simple, but critical to getting smooth, strong control with resistance to damage by external forces.
The difference in how the mask looks when initially placed on the head and when it is positioned and adhered properly to the head is striking. Figure 2-4a shows the mask simply resting on the head early in development, Figure 2-4b shows the difference after attaching the mask to the control surfaces (but not to the back of the head yet) and placement of the eyes. Note the immediate and strong response felt when looking at the second picture, which has an expression (albeit with a slightly ...frumpy expression) rather than simply hanging limply (which the brain seems to immediately disregard as inanimate).


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