Robotics Fundamentals and Sensors
What this domain tests
Robotics Fundamentals and Sensors tests the sense–plan–act loop, robot anatomy, sensor selection and basic sensor calculations. You should be able to explain open- and closed-loop control and interpret resolution, accuracy, precision and range.
Core rules and concepts
- A robot has sensors, a controller, actuators, a power source and often an end effector. Degrees of freedom describe independent motion axes.
- Open-loop control acts without feedback; closed-loop control compares sensor readings with a target and corrects error.
- Sensors include ultrasonic and infrared distance sensors, encoders, inertial measurement units, force sensors, cameras and limit switches.
- Resolution is the smallest detectable change; accuracy is closeness to true value; precision is repeatability; range is the operating span.
- Sensor noise and drift are handled by filtering, calibration and redundancy.
- Ultrasonic sensing uses time of flight: distance = speed × time / 2 because the pulse travels to the object and back.
Worked example
An ultrasonic sensor reports a round-trip time of 0.02 s. Take the speed of sound as 343 m/s. Total path = 343 × 0.02 = 6.86 m. The one-way distance is 6.86/2 = 3.43 m. Forgetting the division by two doubles the answer and is the most common error.
Traps that cost marks
Do not use one-way time in a round-trip formula. Do not assume infrared works well in bright sunlight or on dark, non-reflective surfaces. Do not call an encoder an absolute position sensor unless it is designed that way. Do not ignore sensor noise when tuning a controller.