PEC EPE Mechatronics key terms

A mathematical tool that maps a time-domain signal into a function of a complex variable, converting linear differential equations into algebra so transient and steady-state responses of dynamic systems can be solved.

A mathematical operation that decomposes a signal into the amplitudes and phases of its sinusoidal frequency components, exposing the frequency content used in filtering, vibration analysis and spectral measurement.

A plot of closed-loop pole positions as one controller parameter, usually proportional gain, varies from zero to infinity; it shows how stability and transient response change with gain.

A pair of graphs of a system's frequency response: magnitude in decibels and phase in degrees against logarithmic frequency, read to find stability margins, bandwidth and resonance.

A feedback controller that adds proportional, integral and derivative terms of the tracking error, letting the designer trade steady-state accuracy against speed of response and damping.

The ratio of the Laplace transform of a system output to that of its input with zero initial conditions, describing the input-output dynamics of a linear time-invariant system.

A model of a dynamic system as first-order differential equations in a state vector, written with matrices that map states and inputs to state derivatives and outputs.

Frequency-response stability measures: gain margin is the extra loop gain allowed before instability at the phase crossover; phase margin is the phase lag still permitted at the gain crossover.

An empirical rule for setting PID gains from a plant's step response or from the ultimate gain and period at which the closed loop first oscillates continuously.

A switching technique that varies the duty cycle of a fixed-frequency square wave to set the average voltage or power delivered to a motor, heater or lamp with low losses.

A four-switch power circuit that reverses the voltage polarity across a load, letting a DC motor run in either direction and be braked or driven by pulse-width modulation.

A motor supplied with a feedback device and closed-loop drive so it follows position, velocity or torque commands accurately; selected by torque, speed and encoder resolution.

A brushless motor that turns in fixed angular steps when its coils are energised in sequence, giving open-loop positioning without feedback but risking lost steps under overload.

A single chip containing a processor, memory and peripherals such as timers, converters and serial ports, used as the embedded controller of a mechatronic product.

A hardware or software signal that suspends the running program, executes a short service routine and resumes, letting a processor react to events without continuous polling.

A circuit that samples an analogue voltage and converts it to a digital code; resolution, sampling rate and reference accuracy determine the quality of a digital measurement.

A high-gain differential voltage amplifier used with external feedback to build buffers, filters, instrumentation amplifiers and other analogue signal-conditioning and drive circuits.

A differential, multi-master serial network used in vehicles and machines, where nodes broadcast short frames with priority arbitration and communicate reliably in electrically noisy environments.

A rotary-to-linear drive in which recirculating steel balls run between screw and nut, giving low friction, high efficiency and precise positioning compared with a sliding lead screw.

A compact reducer using a flexible splined cup, an oval wave generator and a rigid ring to give very high ratios with near-zero backlash, often used in robot joints.

The stress amplitude a material can withstand for a stated number of load cycles, read from S-N curves and reduced by stress concentrations, surface finish and mean stress.

Tolerance is the permitted size variation of a part; fit is the planned clearance or interference between mating parts, chosen from standards so assemblies function and interchange.

A symbolic drawing language that specifies allowable form, orientation, location and runout of features relative to datums, controlling function more precisely than size limits alone.

A support for a rotating shaft that carries radial and axial loads through balls or rollers between races; its rating life depends on dynamic load capacity and operating speed.

A resistive foil bonded to a surface whose resistance changes when stretched; connected into a bridge it measures force, torque or pressure through a calibrated elastic element.

A four-arm resistive circuit that converts small resistance changes from strain gauges or temperature sensors into a measurable voltage, using excitation and bridge completion.

An inductive displacement sensor with a movable core that gives an AC output proportional to position, offering high resolution and robustness in industrial measurement.

A temperature sensor of two dissimilar metals joined at a measuring junction, producing a small voltage by the Seebeck effect; cold-junction compensation is needed for accurate readings.

A rotary sensor that emits pulses as a slotted disc passes a detector, providing speed and relative position; quadrature channels give direction and an index pulse gives homing.

The amplification, filtering, isolation and conversion applied to a raw sensor output so it suits the input range and impedance of a converter or controller.

A false low-frequency component created when a signal is sampled below twice its highest frequency; an anti-alias low-pass filter must precede the sampler.

The computation of the position and orientation of a robot's end effector from its joint values using the geometry of the link chain.

The problem of finding joint values that place a robot's end effector at a desired pose; it may have several solutions, one solution or none.

A matrix that relates joint velocities to end-effector linear and angular velocities; it also maps joint torques to end-effector forces and reveals singular configurations.

Four standard values (link length, link twist, joint offset and joint angle) that define each link frame of a serial robot and allow systematic derivation of forward kinematics.

An industrial computer with rugged inputs and outputs, a repeating scan cycle and ladder or structured-text programming, used to sequence machines and interlock plant safely.

A networked supervisory system in which remote terminal units collect field data and a central server displays and commands widely distributed plant from a control room.

A manufacturing metric calculated as the product of availability, performance and quality rates, giving one measure of how productively an asset is used.

The use of programmed coordinates and feed commands to drive machine-tool axes and spindles, so parts are produced repeatedly to drawing tolerance.

The professional duty to protect public safety, health and welfare, to stay competent and honest, to declare conflicts of interest and to sign only work one is qualified to supervise.