Silently waiting in place to start the program for cleaning the rooms based on vacuum concept. This is the intelligent cleaning device called robotic vacuum floor cleaner. In this article, I made a foray into the design and technologies used in these small robots as well as navigation techniques applied to some of the most advanced robots.
A robotic vacuum floor cleaner cannot compete with standard vacuums, these robots are used to maintain cleanliness and less for general cleaning. A slick design and advanced technologies have made from these intelligent machines a success among service robots with huge sales growing every year. A wide range of vacuum robots hitting the market and ready to work unattended for hours at a time set by the owner.
A wide range of sensors, motors, and navigation systems are located in these flat mechanical agents in order to provide environmental information, move and take a decision where and how to clean.
Design
Sensors, wheels, control units, and shapes are part of the robot, part of the design.
A good design means a powerful cleaning robot. A good design involving both the exterior and interior of the robot. At the exterior, robotic vacuums look like a disk-shaped device with squat and round corners and flat body. For a good cleaning on wall corners and under furniture, the flat design has proven to be the best option.
On the top of units is located the control panel. One, two or more buttons or a touch-pad screen helps you set the program and give feedback for control instructions. Most control panels are located on top for a good reason – to not touch by mistake the buttons or touch sensitive interface by objects in the rooms.
Wheels are part of the movement system where in general two wheels are used to drive and one or more wheels as non-driven caster.
Rechargeable battery power the motors, sensors, microcontroller, and all electronic parts. A good run time for a cleaner robot could be 100 minutes, but not all robots passed a working time over 60 minutes. At this time, is added the battery charging time, which often lasts for hours.
The vacuum cleaning system consists of a suction system plus other cleaning systems like brushes to sweep debris for suction. The dirt is collected in a collection bin while filters are used to retain air particles with larger size than 0.3 micrometers (µm).
Additional to a vacuum system, a wide range of cleaning robots uses wet mops and a self-dispensing fluid reservoir.
Sensors
A wide range of sensors, many calculations, and one small microcontroller that control the vacuum robot between the furniture and flowers. With enough memory space the robot scans the entire house and store in the memory maps for navigation when the cleaning mode is activated, or to return at the base for battery recharge.
Obstacles, drops like stairs, dirt, battery usage, or cleaning path are few examples where sensors are the main tool. A wide range of sensors is located into a robotic vacuum cleaner and below I made an overview of most common sensors.
Infrared sensors
This type of sensor is used to avoid obstacles and for navigation. Navigating from room to room, an infrared sensor ensuring a clear run for the robot and provide protection for objects in rooms as well a safety system for the robot.
Ultrasonic sensors
Ultrasonic sensors have the same role as infrared sensors, to keep away the robot from obstacles or to fall from a height.
Accelerometer and Gyroscope sensors
These sensors are included in the same category and are generally used for position, orientation, speed or to have information about acceleration.
Acoustic sensors
A cleaning robot may encounter difficult areas to clean. Acoustic sensors are used for the particular area where the robot must focus for cleaning the zone before leaving that area.
Laser scanner
Advanced technology like a laser scan was also integrated into this small cleaning machinery. These sensors are used to scan the entire house in order to determine optimized path for cleaning and to cover all rooms.
Camera
A video camera can be used for at least two main functionalities: to identify objects and people, or to capture images when the owner connects remotely using the Internet and to control the robot inside the house.
Ultraviolet light
Cleaning after a pet doesn’t always mean an effective cleaning and this is the case when ultraviolet light is used for floor disinfection.
Navigation
It is a hard decision for choosing the best path for cleaning due to a high impact over navigation precision. Complex algorithms working in order to select the right path for cleaning based on sensor information and different conditions depending on the chosen program.
Perhaps a good navigation is the biggest difference between robotic vacuum floor cleaner models. Engineers design many cleaning models including here cleaning programs based on circular or spiral patterns for a large covering, another popular model is the wall-following, and many more models including zigzagging, spot or crisscrossing in diagonals.
These little cleaner robots are different in many ways and come with different features. Multi-room navigation is a common feature, but the navigation mode is often very different. Advanced robotic cleaners have integrated a self-charging mode where the robot memorizes the location where it cleans, return to charging station to recharge the battery, and then return to continue cleaning.
Each new series of a robotic vacuum floor cleaner comes with improved or new navigation systems. iRobot Roomba vacuum cleaner series is perhaps the most popular name and with a wide range of robotic cleaners. A wide range of robots, a wide range of navigation systems. For example, one navigation system used by Roomba robots is AWARE system, which uses multiple sensors for taking environment data.
Other navigation system from Roomba series uses a set of battery-powered Virtual Wall Lighthouses for room-to-room navigation.
Another interesting indoor navigation system is Northstar, the navigation system installed on Mint Plus floor-cleaning robots. This system keeps in memory information about areas cleaned and areas still needed to clean. As well as a Roomba navigation system, Northstar uses small cubes placed around home and send signals like an indoor GPS.
Control
On-board control is a simple control system available in all models. Even a robot cleaner use button or a touch-pad control system, these have the role to give you a full control over the all robot features.
Another way to control the robot is wireless. Here, we can meet two ways to control: using a radio frequency technology like a TV remote, or using the Internet.
Using radio frequency the robot can be controlled from any room at a single touch of the button. In case of travelling, Internet applications allow users to control the robot for cleaning or to use the robot as a security tool.