The servo motors were controlled by a central microcontroller.  Each motor required a dedicated control line to control its position. Power is supplied by two separate battery banks, one for logic components and one for motors. An RS-232 level shifter was used to bridge between the microcontroller and a PC serial port. All the components were then mounted onto a custom manufactured PCB.

The main controller of the six-legged walker was a PIC microcontroller. There is a large variety of PIC microcontrollers available from Microchip ranging. After some research the PIC 16F876 was selected as the main controller. The PIC 16F876  has 22 general purpose I/O pins, 3 internal hardware timers and 14,336 bytes of flash program memory. The 16F876 also offers in circuit debugging and programming functionality to streamline the development process.

The MAX 233 level converter chip was used to convert TTL logic to RS-232 signal and vice versa to facilitate communication between the remote control and the robot.  Two bump sensors were installed on the front of the robot. The bump sensors were made using micro switches with wire extensions to provide adequate reach.

The six legged walker was powered by Nickel Metal Hydride (NiMh) batteries.  The NiMh batteries were designed for high current drain devices.  Due to the fact that the motors were drawing a lot of current, the batteries drained quickly. To reduce the power drain two battery banks were used. One battery bank was for logic control and the other battery pack was for motor and electronics control of the robot.

The robot walker circuitry was built onto a custom made printed circuit board. The PCB layout was performed using schematic capture software with the ability to route traces. The PCB traces were printed onto a transparency for masking.  A pre-sensitized single-sided copper-clad board was exposed, developed, and etched to create the custom PCB. The required component holes were drilled and individual devices soldered into their appropriate locations.




[Home]  [Mechanics]  [Electronics]  [Software]  [Documents]  [Gallery]  [Links]  [Project Team]