I've actually made three robots. new

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This morning I realized that I have actually made three different robots. Three different RC cars with three different physical charcteristics dictated this.

First I built the 1/10 scale model level car based on an HPI SPRINT. It has detailed miniature suspension and handling features, great speed, and proportional control systems based on pulse width modulation. My PIC kit for this car is simple because the controls are digital signals. All that is needed is the PIC and a DPDT switch. The switch - under PIC control - selects which PWM signals (those from the PIC vs those from the radio receiver) go to the steering and driving electronics. The PIC code is quite simple because of the car's capabilities. At $200 - $300 for the car and my kit this seems too expensive for our public schools.

Second I built a 1/12 scale toy level car. This car has bang bang controls. It requires the PIC, the SONARs and four DPDT relays to steer the DC current into the correct connections. It runs slowly enough for the PIC and the SONARs to keep it within reasonable behavior limits. It can be stopped in mid 'flight' by turning ON the radio transmitter. The price is right for our schools, but I feel the car is not fast enough nor exciting enough. It is also too small to carry my KIT under the car skin.

Third I built the 1/10 scale toy car. This car is much faster than the 1/12 scale toy. It too has no proportional controls. The added electronics kit is the same as the 1/12 car, but the code needed adjusting. ie the 150millisec pulses. I think the $50 car price is within budget. My KIT is complex because of the four relays, but hopefully doable by a dedicated teacher and class. The engineering is interesting because, as one of my videos shows, the behavior is a bit unpredictable. Maybe if I had some local help and a more sophisticated program ------

Ken