What is Robot Sensor : Working & Its Applications

Robots are automatically operated machines that are developed for multiple purposes. Robotics includes welding, assembly, monitoring, rescue & recovery and lot more.  There are different types of sensors used in the robot design to meet its particular requirements which are known as robot sensors. These sensors are required within robotics to make them mechanical to avoid uncertainty & attain higher productivity. So without sensors, a robot is blind & deaf. So this article discusses an overview of a robot sensor, types, and applications.

What is Robot Sensor?

A sensor that is used to estimate the condition & environment of a robot is known as a robot sensor. This sensor mainly depends on the human sensory organs’ functions. So, Robots need a wide range of data about their surroundings to work efficiently like position, distance, velocity, size, orientation, acceleration, force, temperature, moment, weight, luminance, etc.

A sensor in a robot allows responding to its environment to perform complex tasks. Every robot requires different sensors to control itself by knowing information about the position, body movement & its parts.

How does a Robot Sensor Work?

The working of every sensor mainly depends on the principle of transduction which means energy conversion. Sensors within a robot allow it to respond through its environment in a flexible technique. By using different sensors in robots, they are capable to observe and sense so that it performs different complex tasks.

Robot sensors measure the condition & environment of robots then inform the controller of robots as electronic signals. So robots need different sensors to control their actions.

Robot Sensor Characteristics

The robot sensor characteristics mainly assist in determining the suitable sensor for the robot in different situations. Some of the necessary features of robot sensors are given below.

• Accuracy
• Dead Band & Hysteresis
• Calibration
• Repeatability
• Resolution
• Linearity
• Drift
• Temperature
• Power
• Usable Temperature
• Output Form
• Storage Temperature
• Spot Size
• Reliability

Types of Robot Sensor

Robotic sensors are available in different types which are discussed below.

Light Sensor

The light sensor is used to discover the light & generates a voltage difference. The light sensors used in robots are two types photovoltaic cells & photoresistors. Photovoltaic cells are used to change the solar radiation energy to electrical and these sensors are used in solar robot manufacturing. Photoresistors are used to alter their resistance by modifying light intensities. When light is more on it then resistance will be less. These light sensors are not expensive, so used easily in robots.

Sound Sensors

A sound sensor is mainly used to detect a sound & change it into an electrical signal. These sensors can be used in robots to navigate through sound. By using this sensor, a robot controlled through a sound can be implemented. So that robot moves right side by a single clap and turns left side with two claps.

Temperature Sensors

A temperature sensor is used to detect the change within temperature in its surrounding. This sensor mainly works on the change in voltage difference principle for a change within temperature to generate the equivalent temperature value of the surrounding.

These sensors can also be used in robots to work in extreme weather conditions such as an ice glacier or a desert. There are different types of temperature sensor ICs available to detect the temperature like LM34, TMP37, TMP35, TMP36, LM35, etc.

Contact Sensors

The contact sensor is also known as a touch sensor which is used in robotics. The main function of the contact sensor is to detect a change within velocity, position, acceleration, torque, or force at the joints of the manipulator & the end-effecter. These sensors need physical contact to work the robot properly & act accordingly. This sensor is utilized in different switches like a limit switch, button switch & tactile bumper switch.

These sensors are extensively used in obstacle avoidance robots. Once the sensor detects any obstacle then it transmits a signal to the robot so that the robot performs different tasks like reversing, turning, otherwise simply stops.

Proximity Sensor

A proximity sensor in a robot is used to detect the object near to a robot & also measures the distance from a robot to some object without any physical contact but they use magnetic fields to sense such objects. These sensors are available in two types IR transceivers, photoresistors, and ultrasonic sensors.

Pressure Sensors

The pressure sensor is used to detect pressure, so these sensors are used in robotics because they are responsive to touch, pressure & force. This sensor is used to design a robot hand to calculate the amount of grip & force necessary to clutch an object.

Navigation Sensors

These sensors are also known as positioning sensors which are used in robots for detecting their positions. The most frequently used navigation sensors are GPS, Localization & Compass.
GPS system or global positioning system is very helpful for outside robots because it simply analyses the received maps from the GPS satellites.

Localization sensor assists a robot to recognize elements externally like natural landmarks & artificial landmarks & process their data to locate their positions.

The magnetic compass is used to provide directional measurements with the magnetic field of the earth to guide the robot in the correct direction to achieve its destination. As compared to GPS, these sensors are very cheap.

Acceleration Sensors

These sensors are used to measure the acceleration & tilt. Two main forces can affect the working of an accelerometer like static & dynamic forces.

The friction between two objects is known as a static force which is used to know how accurately a robot tilts. The amount of force required to move an object is known as a dynamic force which is used to estimate the necessary acceleration.

Gyroscope Sensor

A gyroscope sensor or Gyro is one type of sensor used to measure & help in maintaining orientation through the angular momentum principle or a Gyroscope is used to calculate the rate of revolution in the region of a particular axis. This sensor is very helpful when you want your robot to not depend on the gravity of the earth to maintain Orientation.

IMU Sensor

An IMU sensor, IMU stands for “Inertial Measurement Units” merge two or more sensors properties like Gyro, Accelerometer and Magnetometer to calculate velocity, gravitational & orientation forces.

Voltage Sensors

Voltage sensors are used to change the voltage range from low to high. For instance, an operational amplifier uses less voltage, amplifies, and generates output as high voltage. A simple LED can also work as a voltage sensor to sense a voltage disparity & light up.

Current Sensors

Current sensors are used to monitor the flow of current within a circuit & give an output like a current or proportional voltage. The output of most of these sensors is an analog voltage that ranges from 0V- 5V which can be further processed with the help of a microcontroller.

Floor Cleaning Robot using Ultrasonic Sensor & Arduino Board

The main objective of this project is to design an Automatic home cleaning robot to clean the entire room by detecting obstacles, avoiding and moving continuously until the entire room gets cleaned. This robot is attached with a brush to clean the room. Here this robot uses an infrared sensor along with an ultrasonic sensor because obstacle avoidance can be detected by using an infrared sensor whereas used mainly for fall detection.

The required components to build this project are; Arduino UNO R3, a shoe brush, ultrasonic sensor, Arduino Motor Driver Shield, battery, a power bank to power the Arduino, scotch Brite scrub pad, computer, wheel drive robot chassis.

Circuit Diagram

The circuit diagram of the Automatic Home Cleaning Robot is shown below. This circuit is very simple to design by connecting the ultrasonic sensor to the Arduino board and locating the shield of the Motor Driver onto the Arduino.

The Ultrasonic Sensor used in this circuit is HC-SR04 which is used to measure the distance with stable & high accuracy readings. So, it can measure the distance from 1 inch – 13 feet/2cm to 400cm. It generates an ultrasound signal at a 40KHz frequency in the air. The distance of an object can be measured depending on the time required by the ultrasonic wave to go back to the sensor. If we know the time & speed of sound then we can determine the distance through this formula.

Distance = (Time x Speed of Sound in Air/2.

The connections of this circuit are as follows; The Ultrasonic sensor’s Trig pin is directly connected to the Arduino’s 12th pin. The Echo pin is directly connected to the 13th pin, the voltage pin is connected to the 5V pin & the GND pin of the sensor is connected to the GND pin of Arduino.

Both the pins like Trig & Echo allow the Arduino board to interact with the ultrasonic sensor. Here, voltage & GND pins deliver the power to the sensor & the Echo & Trig pins allow it to transmit & receive data through the Arduino board.

The motor shield must include a minimum of two outputs & they should be connected to two motors. Usually, these two outputs are labeled as M1 & M2. Connect your battery & power bank to the Arduino & motor shield correspondingly.

Program

#include <AFMotor.h>
#define trigPin 12
#define echoPin 13
AF_DCMotor motor1(1,MOTOR12_64KHZ);
AF_DCMotor motor2(2, MOTOR12_8KHZ);

void setup() {
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
}

void loop() {

long duration, distance;
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);

delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance = (duration/2) / 29.1;
if (distance < 20) {
motor1.setSpeed(255);
motor2.setSpeed(0);
motor1.run(BACKWARD);
motor2.run(BACKWARD);
delay(2000); //CHANGE THIS ACCORDING TO HOW THE ROBOT TURNS.
}
else {
motor1.setSpeed(160); //CHANGE THIS ACCORDING TO HOW FAST YOUR ROBOT SHOULD GO.
motor2.setSpeed(160); //CHANGE THIS TO THE SAME VALUE AS YOU PUT IN ABOVE.
motor1.run(FORWARD);
motor2.run(FORWARD);
}
}

First, we need to install the Adafruit Motor Shield Library to drive the two motors. Here, the L293D motor driver shield is used, so need to download the motor Library, and include it in your “Arduino IDE library folder”.

Open the Arduino IDE and Paste the above complete Arduino code into the IDE. After that, need to connect your Arduino board to the computer. Choose the port within Tools or Port & click on the upload button. Check the room cleaning robot. If this robot rotates very slow or very fast then, trial with the delays to get perfect results.

Advantages

The advantages of robot sensors include the following.

• It enhances product quality
• It enhances the accuracy of the application
• It extends the robotic scope applications
• It enhances the safety of the workforce.
• Response time is fast
• The sensing range is long
• Low cost
• Resistant to harsh environments
• Easy to install
• Extremely predictable

Disadvantages

The disadvantages of robot sensors include the following.

• Needs physical contact through target
• Contact bounce
• Detecting range will be affected through color & reflectivity of objective
• Very responsive to severe ecological changes
• Responsive to changes within temperature

Use of Sensors in Robotics

The applications of robot sensors include the following.

• Robotic sensors are mainly used to estimate the condition & environment of the robot.
• These sensors ensure the smooth working of a robot.
• Robot sensors assist robots to respond to the received commands.
• These sensors provide the effortless achievement of different tasks. Understanding the surroundings can assist a robot to decide the object’s proximity, temperature, chemical reaction, sound, and perform accordingly.
• Sensors in robotics are required to attain reliable solutions with efficient quality, fast response, accuracy & cost-effectiveness.

Thus, this is all about an overview of a robot sensor, types, working, and its applications. Here is a question for you, what are the different sensors used in automobiles?