Dual Motor Control for Robots
Presented here is a simple circuit that can drive two motors for a small robot, allowing the robot to negotiate an obstacle course. Two light-dependent resistors (LDRs) are used to detect the obstacle and the motors are driven correspondingly to avoid the obstacles automatically. Two H-bridge motor circuits are used that can drive each motor forward or backward, or stop it, independently.
Circuit and working
Fig. 1 shows the circuit of dual motor control. The circuit is built around four-channel multiplexer CD4052 (IC1), light-dependent resistors (LDR1 and LDR2), four BC547 npn transistors (T1 through T4), four BC338 transistors (T7, T8, T11 and T12), four BC327 pnp transistors (T5, T6, T9 and T10) and a few other components.
Fig. 1: Circuit of the dual motor control |
The motor-control transistors (T1 through T4) are driven by the output of IC1 via diodes D1 through D6. IC1, in turn, is controlled by light-dependent resistors LDR1 and LDR2 mounted at the front of the robot. LDR1 is on the left side, while LDR2 is on the right side.
When an obstacle is detected by both the sensors, the resistances of both the LDRs become high, pulling A0 and A1 inputs of IC1 high. In this case, IC1 connects output ZA to Y3A, and ZB to Y3B, allowing current to flowthrough diodes D5 and D6. This, in turn, switches on transistors T3 and T4, running both the motors in reverse and causing the robot to back away from the obstacle in front of it.
Working of the circuit is simple. The robot moves freely in forward direction as long as it doesn’t detect any obstacle. It moves away from any obstacle and navigates its way using the inputs from the LDR sensors.
Construction and testing
An actual size, single-side PCB for the dual motor control is shown in Fig. 2 and its component layout in Fig. 3. Assemble the circuit on the PCB to save time and minimise assembly errors. Carefully assemble the components and double check for any overlooked error.
Fig. 2: An actual size, single-side PCB for the dual motor control |
Fig. 3: Component layout for the PCB |
To test the circuit for proper functioning, check correct power supply at TP1 with respect to TP0.
Now put an obstacle in front of the LDRs and check change in the voltage levels at TP2 and TP3 as shown in the test point table. With change in the levels at TP2 and TP3, observe corresponding changes on the output side of IC1 as well by monitoring test points TP4 through TP9.
Comments
Post a Comment