Applications - Technology insights

Making Mobile Robots Smarter and Safer

Mobile robots are becoming more commonplace in industry. Most robots are reliant upon advanced anti-collision and navigation systems, which can often be computationally demanding, costly, and difficult to maneuver.
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This article explains how strategically positioned range sensors can provide an adaptable, compact, and inexpensive alternative, proving that it can be easy to utilize this technology.

Automation enhances the consistency, quality, productivity, and safety of industrial processes and since the early 1900s, the role of automation in industry has been increasing. Automation has changed from machines that performed easy and repetitive tasks to industrial robots that gather information and react to the environment around them. [1]

Reliable Navigation Systems are Essential for Safe, Efficient Mobile Robots

Industrial robots are no longer stationary. Now mobile, robots can be utilized in an entirely new set of applications. Tasks that have traditionally been performed by humans or human-operated vehicles are now being completed by robots, for example, the collection of goods and the transportation of goods around warehouses.[1],[2]

Industrial mobile robots must have the ability to navigate increasingly complex and constantly changing environments efficiently and safely.

They must be able to perceive obstacles in front of them and make instant decisions about how to avoid them to achieve this.

A pizza delivery colleague who regularly crashes or drives around the neighborhood aimlessly before delivering a cold pizza would not be desirable. Similarly, people want mobile robots to efficiently complete their tasks without collisions. [2]

Sensors Help Robots ‘See’ their Environment

Collision-based technology, where robots distinguish objects by bumping into them, is the easiest solution for robot navigation. The robot can then adjust its direction to miss the obstacle.

This low-tech solution may be appropriate for basic and compact robots, for example, robot vacuums, but is not likely to be the most effective choice for robotic forklifts traveling around expensive goods and people.[3-5]

Ultrasonic sensors emit sound waves and detect waves that return to the sensor after being reflected by the obstacles.

Ultrasonic sensors can communicate the presence of an obstacle to the robot, but the essence of ultrasonic sensors means that their operation is somewhat restricted and prone to error. Their update rates are slow and their maximum range is frequently short. [3-5]
mobile robotics

LiDAR Laser Scanners Provide Precise Positioning – At a Cost

LiDAR (Light Detection and Ranging) laser scanners provide a high-tech solution for robot anti-collision. They function on the Time-of-Flight principle, where light generated from the scanner reflects from obstacles in front of the robot and returns to the sensor.

The length of time that the light takes to travel from the source to the object and back to the detector is utilized to compute the distance between the object and the robot. [3],[5],[6]

Rotating LiDAR systems use a rotating mirror to divert the laser beams to analyze their complete environment. Laser scanners offer instant and accurate maps of a robot’s surroundings, allowing for precise anti-collision and obstacle avoidance even in changeable situations. However, laser scanners are often costly and deliver thousands of data points each second, creating an excess of data that requires extensive processing power to evaluate.

This implies an expensive system that utilizes a high amount of energy. [3],[5] Laser light can harm human eyes. Therefore, laser scanners must adhere to strict safety regulations.

Thoughtfully Placed ToF Distance Sensors Can Provide Coverage at a Fraction of the Price

It is possible to produce a “selective point cloud” using strategically placed distance sensors to bring a more compact and inexpensive solution compared to traditional environment-scanning ToF technology.

This can also be complementary to full environment-scanning and provide redundancy at a fraction of the price.

Mobile robots can observe their environment and perform anti-collision employing a few single-point distance sensors with the correct sensor configuration. This greatly reduces cost and simplifies the system compared to the modeling and interpretation of their entire 3D environment.
optical sensor array

Figure 1. Left: Anti-collision system using a laser scanner, right: example of object detection using Terabee sensor arrays.
follow me robot

Figure 2. Complimentary technology, overcoming bi-dimensional limitations.

TeraRanger Hub Evo - The Flexible Solution for Mobile Robot Navigation

Our most popular ToF sensor module, the TeraRanger Evo, employs infrared LED light that is safe to the human eye to measure distances. We have created the TeraRanger Hub Evo in response to the demand for flexibility when building custom sensor arrays.
optical sensor array

The hub is a small, octagonal board that enables users to connect up to eight TeraRanger Evo distance sensors and position them in any configuration required. The TeraRanger Hub Evo allows the customer to track several angles with a simplified system.

This competitive flexibility allows customers to select which axes and areas to observe around the robot. The system can also be modified to various applications. This adaptable approach makes prototyping quick and easy. [7],[8]

TeraRanger sensors utilize infrared LEDs that are safe to the human eye as a replacement to laser beams. This means that the sensors can be positioned in more strategic places than laser scanners, with no risk of damaging eyesight.

With the TeraRanger Hub Evo, robots can effectively move around warehouses and other industrial environments while avoiding impacts with people, pallets, and machinery.

This convenient solution decreases the power consumption, cost, weight, and size of the whole system. If the customer already has alternative technologies in place, the TeraRanger Hub Evo and Evo sensors can provide additional functionality and enhance safety at a small cost. [7],[8]

References and Further Reading

1. Industrial Automation and Robotics: An Introduction’ — Gupta AK, Arora SK, Riescher Westcott J, Mercury Learning & Information, 2016.
2. Introduction to Autonomous Mobile Robots’ — Siegwart R, Nourbakhsh IR, Scaramuzza D, MIT Press, 2011.
3. Sensors for Mobile Robot Systems’ — Kucsera P, AARMS, 2006.
4. Performance comparison of Infrared and Ultrasonic sensors for obstacles of different materials in vehicle/ robot navigation applications’ — Adarsh S, Kaleemuddin MS, Bosen D, Ramachandran KI, IOP Conf. Series: Materials Science and Engineering, 2016.
5. Electronic Sensing Technologies for Autonomous Ground Vehicles: A Review’ — Ilas C, Advanced Topics in Electrical Engineering, 2013.
6. Time-of-flight principle’
7. High-performance distance measurement sensor modules’
8. TeraRanger Hub Evo’

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