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What Kind of Sensors Do Public Service Robots Use?


As advanced robots are these days, these artificially intelligent “beings” are still manufactured by humans using human resources. With that being said, robots are powered by artificial intelligence and sensor technology in order to function.

Zoning in on the latter, sensor technology is essentially what “organs” are to humans. For robots, sensor technology allows them to make sense of their external environment and perform tasks accordingly. This article will cover the multiple sensors and sensor technologies that most robots use today.

What Type of Sensor is Used in Robots?

In the field of service robotics, various sensors are being used. Although generally, sensors all have the same mechanical function: to enable robots to calculate the condition and environment they are in for the ability to function, interact with the external environment, and perform tasks.

Let’s get into the specific sensor technologies that allow robots to receive and process data about their surroundings.

Light Sensors

Most robots will have light sensors as these are usually not expensive. These sensors will allow robots to detect light and for some, generate a voltage difference. There are two types of light sensors: photovoltaic cells and photoresistors.

Photovoltaic cells are sensors that are applied to robots to enable them to change solar radiation energy to electrical. Outdoor robots or solar robots will benefit from such sensors as they can harness solar energy.

Photoresistors are sensors that will allow robots to adjust their resistance by having them change light intensities. Simply put, if there’s too much light directed at industrial robots or outdoor robots, then their resistance decreases. Autonomous robots would also benefit from such sensors.

Sound Sensors

Sound sensors allow robots to detect and process different sounds so they can convert them into electrical signals. Simply put, the sounds the robots will hear can be analyzed into sensor data so they can respond accordingly and carry out tasks.

Social robots would benefit from sound sensors especially because they deal with human-robot interaction. A human-robot will also have sound sensors since they need to be humanlike as much as possible and with that comes the ability to recognize and respond to sounds.

Temperature Sensors

For industrial robots and professional service robots to detect any changes in the temperature within the environment, temperature sensors are installed in them. Temperature sensors work by using the voltage difference principle that will ultimately tell robots the temperature change and equivalent temperature value of the environment.

Temperature sensors are needed for industrial robots and professional service robots to function in complex environments and weather conditions. Such sensors would also be useful in a military robot where there are various external forces at play.

Contact Sensors

Contact sensors help robots to detect obstacles without the need for manual guidance. Robots requiring obstacle avoidance would benefit well from this kind of sensor technology as it will help them detect objects so they can reverse, turn, or simply stop to avoid them.

Given that contact sensors help with object detection, they are also interchangeably known as touch sensors. To carry out object detection, contact sensors or touch sensors can detect changes in location, position, acceleration, torque, or force by way of physical contact. With that, these are usually found at the joints of the manipulator or the end-effector for other robots.

Proximity Sensors

Similar to contact sensors are proximity sensors. From the name itself, proximity sensors are sensor technology that will help robots detect objects that may be in close contact with them. Proximity sensors work with the help of magnetic fields for robots to sense any objects within the vicinity.

They can be further categorized into three types: photoresistor sensors, infrared transceiver sensors, and ultrasonic sensors.

Photoresistors Sensors

As discussed above, photoresistors sensors are a type of light sensor that helps in detecting the presence or absence of light and in measuring light intensity.

Infrared Transceivers or Sensors

For robots to detect passive or active infrared sensors, they will need these infrared transceivers or sensors. The active transceivers function as proximity sensors, which is why an industrial robot or military robot would often have these for obstacle detection capabilities.

Meanwhile, passive infrared sensors are needed to detect infrared radiation used mainly for motion-based detection. Mobile robots and automated guided vehicles would often have this type of sensor technology.

Ultrasonic Sensors

For robots to measure the distance between them and an object, ultrasonic sensors will come into play. These sensors work by emitting ultrasonic sound waves and convert the sound that is reflected into an electrical signal thus determining the distance reflected by the waves.

Such sensor technologies help industrial robots and autonomous mobile robots with their robotic systems in obstacle detection and anti-collision safety.

Distance Sensors

Other industrial robots would opt to use distance sensors to measure the distance between objects instead of using proximity sensors. Unlike the latter, distance sensors will measure the distance of objects without the need for physical contact. Instead, sensor data will be retrieved by emitting a signal and getting the difference of the signal when it returns.

Ultrasonic Distance Sensors

Other sensors used to measure distance without the need for physical contact are ultrasonic distance sensors. These types of sensors allow robots to measure the distance of an object by using high-frequency sound waves and calculate the time lapses from the moment they were sent out and relayed back.

Infrared Distance Sensors

Robots can also measure the distance between them and objects through infrared distance sensors. This is done by way of calculating the angle of reflection that is emitted by the infrared waves of said sensors.

Laser Range Sensors

For an industrial robot to be able to measure the range of target objects, it will be needing laser range sensors. These types of sensors will calculate the speed of light about the light waves emitted from the laser and the time it was able to receive the signal.


Encoders are sensing devices that will help industrial robots, collaborative robots, and autonomous robots make sense of sensor data such as count, positioning, direction, and speed. Encoders will use the information and send out the command needed for a robot to do like move its robotic arms.

Various sensors and technology types will create signals accordingly: magnetic sensors, mechanicals, resistive sensors, and most commonly optical sensors.

Stereo Camera

While the use of stereo cameras can be applied in many fields such as machine vision and computer vision for filtering out noisy video signals so they can be transmitted into data, they can be used differently in robotics. Autonomous robots and mobile robots in particular make use of stereo cameras as vision systems and for navigation.

The sensor technologies in stereo cameras help robots in terms of control and sensing, mobile robot navigation, and even off-planet terrestrial rovers. In a large way, stereo cameras function as vision sensors for robots instead of needing manual guidance.

Pressure Sensors

While mostly used in automobiles and industrial automation, there are industrial robots that make use of pressure sensors. Essentially, pressure sensors will help regular pressure emitted from an electrical charge in proportion to the stress experienced, and ultimately convert it to an electronic signal.

Tilt Sensors

Industrial robots, collaborative robots, and service robots in production lines in a smart factory that need to constantly move will need tilt sensors. The sensor technologies of tilt sensors will allow an industrial robot to measure slant angles proportional to the horizontal plane it is standing on so it can maintain a constant position.

Acceleration Sensors

A robot arm, leg, or entire body will be able to tilt and move swiftly in an accurate manner because of acceleration sensors. These sensors will give robots an accurate measure of acceleration and tilt in singular or multiple directions.

Proprioceptive Sensors

These sensors help robots measure their system’s internal state. Acting as a form of thermal management, proprioceptive sensors will monitor the robot’s motor speed, wheel load (if applicable), and battery voltage.

Voltage Sensors

To monitor the voltage data of robots, voltage sensors are installed. These sensors will pick up if the voltage of the robot is extremely high or low, which might indicate that there is an issue.

Current Sensors

Current sensors will monitor the electric current that flows through the wires of the robot. Aside from this, they will also produce a signal in proportion to the current, which later on can be used for further analysis and data.

Sensor Fusion

The sensor fusion combines the strengths of all other sensors such as radars, LiDARs, and cameras to create an accurate image of the surroundings. Thanks to various sensors, sensor fusion will allow robots to have a more precise set of image data that can be used for artificial intelligence and functions.

Navigation or Position Sensors

Position sensors are important for autonomous mobile robots and industrial robots as the sensor technologies will aid them in determining and securing their positioning to a sub-millimeter accuracy. If need be, position sensors will secure a robot arm to be precise in its orientation, position, and even speed, which is helpful if said robot is used in a smart factory or even in hospitals to help guide surgeons.

Position sensors also contribute to the GPS, visual navigation, and bionic navigation of robots instead of manual guidance from humans.

Global Positioning Sensors

Similar to position sensors, Global Positioning Sensors (GPS) help aid robots to find and secure their positions and navigation. The difference here lies in the sensor technologies as the GPS will make use of space-based radio navigation over a long distance. The industrial automation industry will commonly use this, especially for self-driving vehicles.

Digital Magnetic Compass

Mobile robots that will be navigating will need a digital magnetic compass sensor. Similar to a handy compass, digital magnetic compass sensors will prove robots with the measurements they will need based on the magnetic field of the Earth.


Localization sensors will make use of various sensors, like infrared cameras, depth cameras, position sensors, and other related artificial intelligence technology to help robots accurately identify their position within a space and environment. Through localization sensors, robots can be more accurate in detecting obstacles, external forces, and other objects whether they are in an indoor or outdoor environment.

What Sensors Are Used in Surveillance Robots?

There are plenty of sensors used by surveillance robots. Aside from camera sensors to help with their vision, most surveillance robots make use of infrared sensors.

Active infrared sensors are used to detect any movement. This helps them monitor any human motion ahead. Passive infrared sensors are used by surveillance robots to detect any human motion through heat waves that are radiated by the human body.

What Sensors Do Factory Robots Have?

Aside from the sensors aforementioned, factory robots will also have force sensors or torque sensors. A force sensor will allow a robot, such as a robot arm, to accurately assemble objects while using the right amount of strength and pressure to prevent any damage.

Force sensors can also be interchanged with torque sensors. Torque sensors will allow a robot to monitor the forces that are supplied back to a fixture. Aside from factory robots, collaborative robots also make use of torque sensors.

Torque sensors will allow robots to control and operate securely and safely. No matter how complex a procedure is, especially when in an assembly line, torque sensors will assure that the force and speed used by the robot will not damage any object. Torque sensors are handy when handling packages as well.

Other sensors that are frequently used by factory robots are two-dimensional vision sensors that will help them detect any objects that move, which is helpful when an assembly line or conveyor belt is being used.

3D vision sensors are also used, which help a robot identify objects in third dimensions. These sensors are particularly helpful for robots that are placing objects and packages in warehouses.

Collision detection sensors are also useful, as from the name itself, these act as bump sensors so robots can prevent colliding with other objects or machines.

Final Note

What Kind of Sensors Do Public Service Robots Use?

As is, robots nowadays are truly advanced and intelligent because of the sensors and technology they use. From this article alone, we see plenty of types of sensors used only by service robots, surveillance robots, and factory robots. However, there are still other types of sensors that robots, such as robot vacuums, use to make them the intelligent machines they are.

Surely, as the field of robotics and our technology develop, we can only expect sensor solutions for robots to further advance. This makes the world of robots even more exciting and worth keeping an eye out for.

Frequently Asked Questions

What is the difference between industrial robots, autonomous mobile robots, and service robots?

Industrial robots are mainly used for manufacturing. They are automated and can be programmed to perform various functions and commands.

On the other hand, autonomous mobile robots are robots that can act even without the control and commands of humans. With the help of sensors, these robots can understand and function within their environment despite the lack of human assistance.

Lastly, service robots are mainly tasked to assist humans. They can be autonomous, but they can also be programmed and operated through a built-in control system.

Sota Takahashi

Sota Takahashi is a Japanese-born electrical engineer. At the age of 18, he moved to Seattle and completed his Electrical Engineering degree at the University of Washington, Seattle. Being a fan of all things tech, he channels his geeky side through this website, and with his wife Linda, shares knowledge about robot pets and how they can be lifelong and advantageous companions for both children and the elderly.

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