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Section 1.5 Glossary

Sense-Plan-Act (Perception-Planning-Control) Loop
A repeating robot workflow where the system senses the environment, plans a response, and acts through actuators.
Perception (Sense)
The stage where a robot gathers and interprets sensor data to estimate state and environment conditions.
Planning (Plan)
The stage where a robot selects actions to achieve goals while respecting constraints.
Control (Act)
The stage where a robot sends low-level commands to actuators to execute planned behavior.
Feedback
Information returned from sensors after action, used to detect error and correct behavior.
Open-Loop Control
Control without live output feedback; commands are executed without automatic correction during motion.
Closed-Loop Control
Control that continuously compares measured output to a target and updates commands to reduce error.
Setpoint
The desired target value for a controlled variable, such as speed, position, or altitude.
Error
The difference between setpoint and measured output.
Proportional Control (P-Control)
A control method where output is proportional to current error, often written as \(u=K_p e\text{.}\)
Proportional Gain (\(K_p\))
The tuning coefficient that scales how strongly proportional control responds to error.
Integral Control (I-Control)
A control method that accumulates past error over time and pushes the system harder the longer an error persists, often written as \(u_i = K_i \int_0^t e(\tau)\,d\tau\text{.}\)
Integral Gain (\(K_i\))
The tuning coefficient that scales how strongly integral control responds to accumulated error.
Integral Windup
Excessive accumulated error in the integral term, typically caused by an overly high \(K_i\text{,}\) that causes the system to overshoot its setpoint before correcting.
Derivative Control (D-Control)
A control method that reacts to the rate of change of error to anticipate and dampen future error, often written as \(u_d = K_d \frac{de(t)}{dt}\text{.}\)
Derivative Gain (\(K_d\))
The tuning coefficient that scales how strongly derivative control responds to the rate of change of error.
PID Control
A closed-loop controller combining proportional, integral, and derivative terms for improved accuracy and stability.
Steady-State Error
Persistent residual error remaining after transient behavior has mostly settled.
Sensor
A device that provides input data about robot state or environment (for example, camera, encoder, IMU, LiDAR, GPS).
Actuator
A device that produces physical output from commands (for example, motor, servo, pneumatic cylinder, gripper).
Encoder
A sensor that measures rotational motion, commonly used to estimate wheel or joint displacement.
Inertial Measurement Unit (IMU)
A sensor package that estimates orientation and acceleration.
LiDAR
A ranging sensor that measures distance by laser reflections to build geometric environment structure.
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