The following are the General Requirements of a basic robot:
1. Chassis – 1no.
2. Motors – 2nos
3. Wheels – 2nos
4. Castor wheel – 1no
5. Battery and power supply circuit – 1 no.
6. Motor driver – 1no.
7. Controller Board (Microcontroller or other) – 1no (minimum)
8. Display / status indicators – as per requirement
9. Sensors / other input devices – as per requirement
10. Programmer (to load code to microcontroller) – 1no.
11. Software(s) – as per requirement.
12. logic development skills.
Out of above listed 12 points, first 6 points are common and hardly change the items. These are mainly hardware items and does not require any software skills. Same robot can be modified to required configuration by changing micro-controller / sensors / inputs / displays / software / logic.
The Small Robot is simple in construction, compact design and have mainly two parts. The first part , Palm Robot – Base Frame, contains the 1 to 6 items of the above list and second part, Small Robot – Control, contains the 7 to 12 items of the above list. By using Small Robot Base Frame, time is saved to develop logic using various micro-controller(s) and software(s).
The Small Robot control systems are designed/developed using AVR microcontrollers here. But, the same logic can be developed using PIC or other microcontroller(s) and the output of the logic can be used to control the Small Robot Base Frame.
About Base Frame:
The Small Robot – Base Frame, contains two B.O. motors with 200 rpm are attached to a chassis on either side and two suitable wheels are mounted on it. A castor wheel with bracket is fixed on front side of the chassis. A 7.4V Li-ion battery is placed between two B.O.motors. 4 or 6 nos of long bolts may be suitably arranged on top of the chassis to hold circuit boards.
A circuit board, called Main Board, with motor driver IC (L293D) and two separate 5VDC regulated power supplies are fixed on top of the chassis, which hardly covers half of the chassis and makes room for adding microcontroller board of one’s choice. One of the 5VDC supply may be used for microcontroller board and sensors. The other 5VDC supply or 7.4VDC from the battery may be used for motors by selecting jumper J1. Due to separate 5VDC supplies, the microcontroller board have least impact of voltage fluctuations due to motors.
A six pin berg strip is available on the Main Board. Out of 6 pins 2 pins are Ground and 5VDC supply for Microcontroller board and remaining 4 pins are data input pins (D3, D2, D1, D0) for motor control. The logic for control of motors are as follows:
Circuit Diagram of Main Board
A PCB is required to assemble all the components shown below in the circuit diagram. For Small Robot, the PCB is fitted on the top of the chassis, where as motors (with wheels), castor wheel and battery is fitted below the chassis.
Making Base Frame is mandatory to add various types of controls.