Mechatronic Systems and Components
System view first
A mechatronic system is the deliberate integration of mechanics, electronics, sensors, actuators and software into one function. Candidates must be able to draw a signal chain: sensor → signal conditioning → controller → power stage → actuator → mechanical load, with feedback closing the loop. Know typical components and their roles: inductive/capacitive/optical sensors, incremental and absolute encoders, strain gauges, DC and stepper motors, servomotors, frequency converters, gears, lead screws, belts, linear guides and bearings.
Traps in questions
- Confusing resolution with accuracy of an encoder; resolution is the smallest step, accuracy is closeness to the true value.
- Mixing up holding torque and pull-in torque of a stepper motor.
- Ignoring backlash, elasticity and friction when asked about positioning accuracy.
- Forgetting that a gearbox multiplies torque while reducing speed, and adds lost motion.
- Assuming a sensor's output is linear over its whole range.
Worked example
A stepper with 1.8° step angle drives a 5:1 reduction gearbox on a 4 mm-pitch lead screw. Steps per revolution = 360/1.8 = 200. Output steps per motor revolution after gearing = 200 × 5 = 1000. Linear resolution = 4 mm / 1000 = 0.004 mm = 4 µm. Rule of thumb: always carry units through the chain and check whether the gear ratio multiplies or divides.
Practical competence
Be ready to describe how to select a drive for a given load: calculate torque from force and lever arm, add acceleration torque, apply a safety factor, and check the motor's speed-torque curve. Understand protection classes (IP), mounting, lubrication and thermal limits of components as part of system design.