Five Reasons to Use Machine Control in Heavy Construction
Simply defined, machine control is a system that calculates the position of the tool on a piece of machinery – like the bucket of an excavator or the blade of a bulldozer – and, via a display, lets the machine operator know exactly what’s going on. It tells you how much earth has been taken out and if you have met the target depth needed for your road, for example. It’s a key part of a digitised construction site that’s making heavy construction work faster and safer. Here we give an overview of machine control and automation and outline five reasons why heavy construction can benefit from reality capture, whether you are an operator, an engineer, or a project owner.
Introducing the two types of machine control: guidance and automation
We generally split machine control into two categories. First, we have machine guidance. The system compares the position of the tool with the 3D design of the site and uses the difference between those values to tell the operator what’s going on. It’s then up to the operator to drive the machine to its required position and stop when the job is done. The 3D design normally comes in the form of triangulated surface models or digital terrain models (DTM), which are uploaded using a USB stick in the case of a single machine, or more conveniently for multiple machines, via Leica ConX, a cloud-based platform for sharing data that can be managed centrally.
Secondly, we have machine automation. Machine automation does the same calculations for the position but has an added interface that takes some of the work out of the operator’s hands. By using hydraulics or connecting to systems on the machine, machine automation can position the machine itself and meet the desired value, such as digging to the correct depth. This is generally found on dozers, graders, and paving solutions, where accuracy can be achieved much more easily than using a guidance-only system.
The trend in the industry is for guidance systems to become more and more automated. The excavator system especially has seen many developments over the past 12 months, including the semi-automatic excavator. We have drilling systems that can stop drilling automatically when the machine control tells the system that it’s hit the desired depth, and solutions for dozers and graders interface with the machines’ hydraulic system for an automated operation.
How it works: positioning data
Generally, machine control requires some instruments to position itself, and there are a few ways of doing this. Firstly, in simple cases, if you’re only concerned with height, for example, you can use a rotating laser. We refer to this as a 2D machine control system. Secondly, you can use a total station or laser scanner to acquire position and height, which is true 3D machine control. This is used for applications that require a high level of accuracy: like trimming and grading applications for roads and rail. Finally, the most common positioning type for machine control is GNSS, which will position the machine to 3D accuracy of roughly 30mm. In all these cases, the initial positioning is not done to the position of the tool itself, so there are other sensors installed to transfer the position from where the sensor sits on the back of the machine to the contact point of the tool.