Air-conditioner feedback diagram

Q4. A vehicle travels along a circular path as shown in the figure below. Two sensors, L and R, whose revolution speeds are independently controlled, are attached to the left and right rear wheels. Sensors L and R are photo-reflective sensors, and their values change according to the ratio of black and white regions they pass over. If the ratio increases, the sensor value decreases, and if the ratio decreases, the sensor value increases. Which of the following is an appropriate control to ensure that the vehicle travels along the black outline of the circle? Here, if the values of the two sensors are equal, the motor revolution speeds return to the initial values. Motor L Motor R Control unit Sensor L Sensor R Circle Rear wheels Moving direction Front wheel Sensor L value > Sensor R value Sensor L value < Sensor R value Motor L Revolution speed Motor R Revolution speed Motor L Revolution speed Motor R Revolution speed Diagram/table transcription: The original vehicle diagram places Sensor L and Motor L on the left and Sensor R and Motor R on the right, with a control unit, rear wheels and front wheel. The choice table compares Motor L and Motor R revolution-speed changes first for Sensor L value > Sensor R value, then for Sensor L value < Sensor R value.

The original image above preserves the complete exam wording and layout.