To convert Sharp IR Rangers to I2C, I now use an ATtiny44a for signal processing.
The latest Sharp Ranger I2C Adapter prototypes.
The new approach, guided by Atmel application note AVR121 (pdf), works much better than the dedicated ADCs I was using and will form the core of my Sharp I2C adapter, available soon, after I make a few usability tweaks and finish the firmware.
Here's how I improved performance with oversampling and filtering.
Safety switch? Takeover circuit? RC Mux? Kill switch? Whatever it's called, this circuit is how you take over control of your autonomous rover milliseconds before it crashes itself into a curb, lake, or ankle. And I've just redesigned mine. Here are the deets. (Meanwhile, it's now for sale on Tindie)