Robotics Pre Finals

Sensor

A device that measures some attribute of the world.

Active sensors

Put energy into the environment to either change the energy or enhance it.

Active sensing

Connotes a system using an effector to position a sensor to improve data gathering dynamically.

Passive sensors

Rely on the environment to provide the medium for observation. For example, a camera requires a certain amount of ambient light to produce a usable picture.

Transducer

A device actuated by power from one system and supplies power to a second system, usually in another form. In addition, the sensor’s mechanism, or element, transforms the energy associated with what is being measured into another form of energy.

Actuator

A mechanism for moving or controlling something indirectly instead of by hand.

Random error

This is caused by fluctuations in the environment or in the sensor itself.

Systematic error

This is caused by a consistent sensor or measurement system bias. Systematic errors can be corrected by calibrating the sensor or adjusting the measurement system.

Drift error

This occurs when the sensor readings gradually shift over time, even when no external factors are changing.

Interference error

This is caused by interference from other sources, such as electromagnetic interference (EMI) or crosstalk between sensors.

Nonlinearity error

This occurs when the relationship between the sensor input and output is not linear.

Hysteresis error

This occurs when the sensor readings are affected by previous measurements, causing a lag or delay in the response.

Resolution

The minimum difference between two values that the sensor can measure.

Accuracy

The uncertainty in a sensor measurement with respect to an absolute standard.

Sensitivity

The smallest absolute change that a sensor can measure.

Linearity

Whether the output produced by a sensor depends linearly on the input

Precision

The reproducibility of the sensor measurement.

Bandwidth

The speed at which a sensor can provide measurements.

Dynamic range

Under normal operation, this is the ratio between the limits of the lower and upper sensor inputs.

Shaft Encoders

Measure the number of turns the drive motor has made; the shaft encoder works the same way an odometer on a car works.

Odometry

Use of motion sensors to determine the robot’s temporal change in position relative to some known position.

Linear encoders

Measure straight-line motion. Sensor heads that attach to the moving piece of machinery run along guideways. Those sensors are linked to a scale inside the encoder that sends digital or analog signals to the control system.

Accelerometers

Can also provide dead reckoning information and often do much better than odometry.

Rotary encoders

Measure rotational movement. They typically surround a rotating shaft, sensing and communicating changes in its angular motion.

Gyroscopes

A device used to measure or maintain orientation and angular velocity.

Proximity Sensors

Directly measure the relative distance (range) between the sensor and objects in the environment.

Ultrasonic Sensor

Uses sonar to determine the distance from an object. This sensor utilizes acoustic energy to detect objects and measure distances from the sensor to the target objects.

Motion Sensor

Is an electronic device that is used for motion detection.

Hall Sensor

Is an omni-polar magnet sensor used to detect magnetic objects

Light Sensors

Are used to detect light that creates a difference in voltage signal to provide feedback to the robot’s system.

Infrared Sensors (IR)

Emit near-infrared energy and measure whether any significant amount of the IR light is returned. If an obstacle is present, it returns a binary signal.

Photodiode

A reverse-biased semiconducting optical sensor that is biased against its easy flow direction so that the current is very low.

Flame Sensor

Can be used to detect fire or other wavelengths at 760-1100 nm light. The detection angle is roughly 60°, and the sensor is particularly sensitive to the flame spectrum.

Temperature Sensor

Provides temperature feedback to a system controller to make decisions.

Gas Sensors

Are widely used to detect gas leakages of LPG, Butane, Propane, Methane, Alcohol, Hydrogen, and smoke in houses and factories.

Joystick Module

Simply connects to two analog outputs based on the commands: X and Y control. It is made up of two potentiometers and a press button, which provides a solution to move robots to a target directly.

Force sensor

Usually used to measure external mechanical force input, such as in the form of a load, pressure, or tension.

Tactile sensors

Are generally used to mimic the sense of touch. Usually, tactile sensors are expected to measure small variations in force or pressure with high sensitivity.

Bump Sensors

Consist of two layers forming a protruding ring around the robot.

Digital Tilt Sensor

A digital tilt switch in which there are two modules: mercury-based and ball-based.

Capacitive Touch Sensor

When any object with capacitive characteristics comes close to a capacitive touch sensor, it acts as another capacitor due to its dielectric nature.

Vibration Sensor

A digital plug that plays sensor blocks. It is made up of a spring and a conductive material passing through the center of the spring.

Computer Vision

Refers to processing data from any modality that uses the electromagnetic spectrum to produce an image.

An image

A  way of representing data in a picture-like format where there is a direct physical correspondence to the scene being imaged. A different technique, color histogramming, can be used to identify a region with several colors.

CMOS sensor

The architecture of CMOS sensor arrays is like that of standard memories in which individual pixels can be randomly addressed and read out.

Charge-coupled Devices (CCDs)

Charges must be transferred from one pixel to the next until they can finally be read out at an array boundary.

Line-tracking Sensor

Can detect white lines in black and black lines in white via the TTL signal.

Color Sensor

A complete color detector that can detect and measure a nearly limitless range of visible colors. The applications include test strip reading, sorting color, ambient light sensing/calibration, etc.

RGB-D sensors

Unconventional visual sensors that can simultaneously obtain a visible image (RGB image) and a depth map of the same scene. They have been very popular in the robotics community for real-time image processing, robot localization, and obstacle avoidance.

Sound Sensor

Used in detecting loud sounds in an ambient environment. It uses an electret condenser microphone to convert sound energy into an electrical signal, just like how a speaker operates.

Voice recognition

A technology through which sounds, words, and phrases spoken by humans are converted into electrical signals.

Radio-frequency identification (RFID)

This technology is based on the response of a tag to radio frequency signals.

Biometric sensors

  Methods for biometric authentication include iris scans, fingerprint sensors, and face recognition.

Laser sensors

Can be utilized in several applications related to positioning. It is a remote sensing technology for distance measurement that involves transmitting a laser beam toward the target and analyzing the reflected light.

LIDAR Light Detection And Ranging (LIDAR)

Has many applications in robotics, including object detection, obstacle avoidance, mapping, and 3D motion capture.

Global Positioning System

Works by receiving signals from satellites orbiting the Earth. The receiver calculates its position relative to at least four GPS satellites in terms of latitude, longitude, altitude, and change in time.

Motors

These are commonly used to control the movement of robot joints, wheels, grippers, and other parts. They can provide precise and accurate control over motion, allowing robots to perform tasks with high accuracy and repeatability.

Servo Motor

Is controlled with an electric signal, either analog or digital, which determines the amount of movement. It provides control of position, speed, and torque.

Speed of a DC motor

Directly proportional to the supply voltage with a constant load.

AC motor speed

Determined by the frequency of the applied voltage and the number of magnetic poles.

DC servo motors

Are commutated mechanically with brushes, using a commutator, or electronically without brushes.

Brushed motors

Have two main parts: a rotor (the rotating part) and a stator (the stationary part). The rotor consists of a shaft with a permanent magnet, and the stator contains an electromagnet. When a current is applied to the stator, it creates a magnetic field that interacts with the rotor’s magnetic field, causing the rotor to turn.

Brushless motors

Do not have brushes or commutators. Instead, they have a stationary part called a stator that contains multiple electromagnets and a rotating part called a rotor that contains permanent magnets. A controller applies electrical currents to the electromagnets in the stator in a specific sequence, causing the rotor to turn.

Stepper motor

A brushless synchronous DC motor that features precise discrete angular motions. This motor is designed to break up a single complete rotation into several much smaller and essentially equal part rotations.

Linear motor

Operates on the same principle as an electric motor but provides linear motion. Unlike a rotary machine, a linear motor moves the object in a straight line or along a curved track.

Hydraulic actuators

Are driven by the pressure of the hydraulic fluid. It consists of a cylinder, piston, spring, hydraulic supply and return line, and stem. As such, they can be used in construction machinery and other heavy-duty equipment.

Pneumatic actuators

Have been known for being highly reliable, efficient, and safe sources of motion control. These actuators are driven by pressurized air that can convert energy in the form of compressed air into linear or rotary mechanical motion.