Navigation & Safety Systems that drive Mobile Robots is the core feature of mobile robots that enables the robot to direct itself from the current position to the desired destination. Navigation of mobile robots has been traditionally understood as solving the problem proposed by these three questions:
- Where am I?
- What are the other places related to me?
- How do I get to other places from here?
These questions involve the determination of a collision-free path from one point to another while minimizing the total cost of the associated path. Depending on the nature of the environment, path planning can be divided into a static and dynamic environment. In a static environment, everything is static except mobile robot where obstacles change their place to time, it is also referred to as static path planning. And if obstacles change their place and orientation to time, then it is referred to as dynamic path planning. Mobile robot in a dynamic environment is finding the shortest possible path from an arbitrary starting point towards a defined goal which needs to be safe (obstacle avoidance) and smooth movement as well as possible.
Popular Mobile Robot Navigation Technologies
With the advent of the Internet of Things (IoT) & Industry 4.0 mobile robots have been used for many applications in various fields such as industry, space, defence, and other social sectors. They have been used for material handling, picking, special applications such as disinfectant robots, etc. Therefore, an intelligent mobile robot is required that could travel autonomously in various static and dynamic environments. Several techniques have been applied for mobile robot navigation and obstacle avoidance. Let’s understand some of them,
LIDAR Based Navigation –
There are several ways for sensors to map and track the environment and estimate mobile robot positioning.
LIDAR – Light Detection and Ranging technology is an essential ingredient in robotic autonomy and navigation. It allows mobile robots to extend outside controlled situations and pre-defined task functions in unpredictable and unfamiliar situations. Lidar sensors provide a constant stream of high-resolution, 3D information about the mobile surroundings, including locating the position of objects and people. Simultaneous Localization and Mapping (SLAM) technology enables the indoor capabilities of a robot with the Lidar data. The benefits provided by SLAM technology include “easy navigation without reliance on external technologies and real-time formation of 3D maps with reduced cost and power requirement”.
Vision-Based Navigation –
Vision system of the robot allows the mobile robot to see its environment as a human sees and interpret the information. Vision-based navigation technique uses a computer algorithm and data from optical sensors calculate the optimal path. The algorithm translates the visual information into concentration surroundings data so that the location of mobile robot can be identified & from there it chooses an optimal path to accomplish its goal. After that, the driving system of the mobile robot will be activated to reach its destination.
Why vision for navigation?
The conventional robot navigation systems, using traditional sensors like ultrasonic, IR, GPS, laser sensors or magnetic tape-based navigation etc, suffer several drawbacks related to either physical limitations of the sensors or being significantly expensive. Vision sensing has emerged as a popular alternative where cameras reduce the overall cost and are flexible.
The impact of mobile robots within warehouses and factories is set to accelerate over the next five years. According to research and advisory firm LogisticsIQ, the warehouse automation market will be more than double from $13 billion in 2018 to $27 billion by 2025. With more robots expected in the workplace issues around safety and security will become more important for those working alongside them. According to Lewandowski, “Safety is fundamental”, so to take care of these safety concerns mobile robots are loaded with a 2-level sensory system, 3D cameras, and many other safety protocols. Let’s delve a bit deeper into each of them.
How safety sensors work?
Many of the mobile systems are based on the LIDAR (light datection and ranging) technology so, from a safety standpoint, the point of entry is to make sure you have what is recognized as a capable safety system to detect objects and people and to react appropriately. This also allows the robot to assess appropriate risk behaviour models, which is essential for managing safety in robot-human collaboration.
Mobile robots working outside can depend on geolocation capabilities, such as GPS alongside detecting technologies including LIDAR, to figure out where they are and where they are going to. That isn’t commonly conceivable inside. Mobile robots working inside utilize simultaneous localization and mapping (SLAM) technology that uses LIDAR’s information to build a map of the robot’s environment and find the robot inside that map.
Mobile robots safer than conventional or manual vehicles, as they are equipped with components that help them to become more autonomous, find the correct path while in motion, make them more capable to detect and diagnose faults and understand the surrounding environment.
Let’s take a brief look at what these components are and how do they work:
- 3D Depth Camera: One of the main safety components is the Camera to visualize every time a mobile robot passes through some object.
- Ultrasonic Sensors & Mechanical bumpers: Apart from LIDAR and depth camera, other sensors like ultrasonic and mechanical bumper (physical contact sensor) have been used in mobile robots. To avoid Collison with unexpected obstacles, these sensors help for detecting and mapping.
- Warning and Alarm Lights: Waring lights give audible warning signals to mobile robots, when the mobile robot is approaching a turn, the warning lights function as directional signals to alert personnel in the area of the mobile robot’s intention to branch right or left.
- Audible Warning/Alarm Signals: If any distinct tones such as songs, the noise will occur during the operation of mobile robots – alarm warning tone will get activate.
- Emergency Stop Buttons: When mobile robots enter an emergency stop state, emergency stop buttons automatically become active and stop the robot to move.
Equipped with the above mentioned critical components and systems, mobile robots are constantly evolving into human-friendly and making the machine-human interaction an everyday reality.