Certus MEMS INS improves efficiency of LimnTech Scientific road-marking solution

Road marking – essential, but slow and dangerous

Road marking is an essential element of our typical daily travel lives. Bright, visible markings not only make finding our way and understanding the route ahead easier, but are essential in making roads safer for motorists and pedestrians alike. We may take road marking for granted, however, with constant increases in road networks, regular grinding and repaving of road surfaces and the need to repaint worn and faded line-work makes the road marking segment a major operation in many countries.

The most common means of road marking is a very manual process. Manual marking typically means using measures to obtain the necessary distances from kerbing and string lines to create the initial travel path for the painting vehicle. The painting vehicle then follows, with a driver and a paint operator in the back of the vehicle. The paint operator ostensibly follows the path visually, adjusting the paint gun carriage alignment with the markings and activating the spray guns as required. This process is slow and capable of somewhere between 0.8 to 1.5 km (0.5 to 1 mile) per hour.

The manual process requires a crew to place and remove safety marking cones and signage and other protection systems, perform measurements and create the line path markings. This means a lot of people moving ahead, around and behind the painting vehicle. To make matters worse, roads are generally not closed when marking is carried out and this places layout crews and paint operators at huge risk of injury through accidents. The sad reality of people being injured and killed while road marking spurred the design team at LimnTech Scientific to find and develop new ways that would take workers off the roads and make the whole road marking process safer and more efficient.

The project: Automate road marking and increase safety and efficiency

In 2010, the concept of an automated painting system was first drafted, with LimnTech Scientific formed in 2012 to bring the idea into reality. The challenges in designing a practical solution that would meet the brief of higher safety and efficiency were several fold. Nominally:

• An AI-enhanced detection system that can recognise existing line markings. This includes line start and stop, width and pattern data.
• A paint system that is mounted on an automated carriage.
• An accurate and reliable RTK compatible MEMS navigation system that provides positioning data and driver guidance.
• A control system to seamlessly coordinate each module and allow the vehicle operator to safely drive the vehicle.

With above requirements met, the LifeMark system was created. The LifeMark system uses an AI-enhanced machine vision camera or laser technology that is capable of determining line markings or remnants of markings in almost any condition. In conjunction with the detection system, a GNSS-based MEMS INS navigation system is used to stamp location data for roadway markings. Real-time kinematics (RTK) for location data is used to enhance accuracy down to <50 mm (2”). All road survey data is stored in the cloud for future use. After surveying, the driver of the painting vehicle uses the control panel to follow the route markings – the paint carriage and spray system automatically apply the paint at the correct locations, without requiring workers on the road. By storing the road marking locations, the work can be repeated without having to survey the road again beforehand. The road marking survey can be carried out at actual traffic speed (up to approximately 130 km/h (80 mph) and the painting at a pace of approximately 24 to 32 km/h (15 to 20 mph). The speed of this automated system represents massive savings in time and greatly increased safety, however, it requires a navigation system that can deliver reliable data for as long as possible.

The team at LimnTech Scientific and sister company, Guidemark have more than 900 years collective experience in line marking systems machinery design and manufacturing to draw on. It is a goal for the company to not only remain at the top of the industry but to lead it in terms of adopting the latest robotic and smart automation technologies that assist their clients in delivering safer roads, safer working environments more efficiently and cost effectively than ever before. To do this requires rugged, reliable equipment with very high levels of dependability in conditions that can affect GNSS.

The challenge: Increasing MEMS navigational accuracy in GNSS impaired environments

Accurate and reliable navigation in rural and urban environments often means dealing with dense tree coverage, overpasses, buildings and tunnels that can all frequently disrupt and deny GNSS reception. For customers, availability of the system is paramount as any time it is not available, additional resources are required. From the perspective of commercial viability, customers generally require a minimum 50% system availability. This places great emphasis on the navigation system being effective in adverse conditions for as long as possible. The deeper you can go into territory that can affect the navigation system and still maintain automated operation, the more efficient the overall solution is and the less time is spent reverting to manual processes.

Heavily forested areas can be a big challenge to satellite-based navigation for automated road marking

The first commercially viable version of the system used Spatial Dual GNSS INS, which provided good, consistent performance, particularly in more open-sky areas. However, as adoption of the system became more widespread, some of  the conditions under which the system was expected to work became increasingly difficult. In the heavily wooded New England area of the United States, where roads are often narrow and closely lined by tall trees as a case in point, the system designers wanted to provide better performance and system availability. This prompted the research and development team to look at improving accuracy and reliability of the GNSS MEMS navigation system in these very difficult environments.

The result: Greatly improved reliability in GNSS compromised areas

After launching the LifeMark product, the LimnTech Scientific team received positive market success due to the safety benefits, efficiency and cost reductions it offered. The demand for LifeMark is spreading across the United States and into areas that are traditionally very difficult for GNSS-based navigation systems to handle. In response, the LimnTech Scientific team needed to improve the navigation system so it could remain reliable in areas that had rendered the previous system inefficient. After investigating comparable navigation units from various manufacturers, the team settled on Certus as it provided notable improvements in maintaining reliable positioning data.

The sales team used various comparison data between the Certus and other navigation systems (see example image above) to demonstrate improvements to potential customers, and existing clients with the previous system. This was especially important to users in areas that have adverse conditions to deal with.

“In some cases, we have seen use of the system going from 40% to 70%. This provides great confidence in clients to use the tool more often.” commented Davies.

The LifeMark system had achieved its design brief of making road marking safer, more efficient and accurate. With the adoption of Advanced Navigation Certus MEMS INS, however, this efficiency is being markedly improved and extends across more difficult territory. For customers, the greater the distance that the system remains operable, the more savings are made in time, cost and hazard exposure. The net result for customers is greatly extended areas where automated road marking can be performed.

The end goal is to eliminate faded or non-existent road markings with accurate, bright and safer markings

The use of Certus MEMS INS has helped LimnTech Scientific improve the performance of their LifeMark solution, especially in penetrating further and more reliably into areas with variable GNSS reception quality. Upgrading to Certus from Spatial Dual has not only helped LimnTech Scientific avoid engineering overheads in upgrading hardware, but enabled them to increase the performance of the LifeMark solution whilst remaining competitive in terms of cost. A valuable additional benefit for existing customers is that they have a very cost-effective upgrade path.