Eye's / Tilt Sensor

simple hack is to diconnect the tilt sensors and replace the eyes with tri-colour LED's. I started working on this its a fairly simple idea (as can be seen from the diagram bellow) I even created a few circuit designs for it (also bellow). But I rapidly discarded it, Disconnecting the tilt sensors is fine, but I'mn not happy with the eyes. I need to think about this some more and come up with something much better and much more fun.

Well, I came up with some more fun things to do with the eye's. Using two different sorts of counters, and a 555 timer I have created some interesting effects. However a circuit actually constructed using these would be to large to really use, but I have included them here for reference. I will have to use a microcontroller to handle the eye's. The chips I chose to use, were mainly chosen for convinience (ie, I had them already) and should not be taken as the best for this application.

This 555 circuit should produce pulses allowing be to change colours between 2-3hz and about 30-40hz.

This 4017 based circuit will cause the LED's to flash in sequence (Red, Green, Blue), it will self reset back to the begining of the cycle.

This 74LS163 based circuit will cause the LED's to flash in binary sequence (Red, Green, Red + Green, Blue, Blue+Red, Blue+Green and Red+Green+Blue)

The outputs from these circuits then goes through a driver stage, the reason for this is twofold. One, because each colour segment of my tri colour LED has differing voltage/current requirements. The second reason is to allow the mainboard to switch the LED's on and off regardless of the current state of the colours.

You can see some crappy video of the eyes flashing at various speeds and paterns here and here. Notice that seen through the face Green appears White.

Tilt Sensor

The V2 has three tilt sensors. One in each leg and a third in the groin at the back. These appear to consist of a trapped metal ball-bearing, which when the robot is tilted, rolls onto two metal contacts closing the circuit. The Right foot tilt sensors senses backward tilt, the left foot tilt sensor senses forward tilt. I beleive the groin tilt sensor detects that the torso is vertical, based of the orientation, but I can't be certain since mine appears to be broken.

The left tilt sensor connects via the 6 wire cable that connects to the mainboard at the bottom left. The right tilt sensor connects via the 7 wire cable that connects to the mainboard at the bottom right. The third tilt sensor connects via the two wire "gray" cable just about and to the right of where the right tilt sensor connects.

Disconnecting the tilt sensors is a simple matter.

Backward Tilt Sensor - Left Foot
Disconnecting the "SV" wire (green on my cable) is all that is required to disable the tilt sensor.


Forward Tilt Sensor - Right Foot

Again, disconnectiong the "SV" wire (blue on my cable) is all that is required to disable the tilt sensor.


It may be necessary to also disconnect the third tilt sensor.

Power Switch

Since I already have a large bundle of cables coming out of the back of my V2, I decided to power it from an external supply. While you can solder directly onto the marked pads on the V2's mainboard (GND, 6V and 9V), I decided against this. Mainly because I have other plans for those pads and I didn't want to ever be in a situation where it was drawing power from both the external power supply and the batteries (This shouldn't cause any fatal problems, I just don't want to do it), since the batteries must remain installed for balance. I had previously noticed that the power switch was DPDT, so there were spare connections for his "Off" position. Which is where I attached my power cable. I will provide some graphics when I get it working properly (at the moment he complains his brain supply is low because I am using a damaged 5 volt supply). The only downside is you still need to solder a wire to the mainboard.

I replaced the 5 volt supply, but the LM7805 seems unable to supply enough current to the robosapien, so I went with a LM317t based circuit. The schematic for which is shown bellow. The can either be used from an external supply, or wired to the V2's internal 9v batteries.

In the graphic bellow you can see where I wired onto the V2's power board. You also need to attach the -9volts onto the mainboards ground, I suggest using some form of shielded crimp connector on the wire to allow you to seperate the power board from the motherboard when required.