LiDAR and 3D Machine Control

Randy Noland, Editor of MachineControlOnline.com3D Machine Control is comprised of various sensors, which converge and define the system’s core capabilities. The sensors gather and communicate data to a control box (computer) that is loaded with application software. The software analyzes this data, presenting appropriate application-centric feedback to the operator via its software user interface. (See Anatomy of a 3D Dozer)

Traditionally, sensors used for 3D Machine Control and positioning include robotic total stations, GNSS receivers, sonic sensors, laser transmitters & receivers, axial sensors, inertial measurement units (IMU) and imaging systems. As sensor technology evolves and new technology emerges, so do 3D Machine Control systems.

Given this overview, it becomes easier to understand the importance of evaluating the potential role different technologies can serve in augmenting or replacing existing sensor technology further refining system capabilities. Lets take a look at LiDAR and the potential it brings to 3D Machine Control.

LiDAR is a Sensor
Point Cloud LiDAR (Light Detection and Ranging) as defined by Wikipedia “is an optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target. The prevalent method to determine distance to an object or surface is to use laser pulses. Like the similar radar technology, which uses radio waves, the range to an object is determined by measuring the time delay between transmission of a pulse and detection of the reflected signal.”  LiDAR is a powerful, data gathering tool. Current applications include geomatics, mobile mapping, GIS, archaeology, geography, geomorphology, geology, seismology, forestry, remote sensing and even music videos.http://machinecontrolonline.com/content/view/6875/

Given these uses, minus the music video application, it is not a surprise to consider LiDAR for construction site planning and heavy highway as-builts. Lets venture into the visionary space and discuss LiDAR as it could relate to grading applications and 3D machine control.

HDL 64E

Robust 3D Data Collection
There are several LiDAR sensors on the market. I will list references at the end of this article, but one in particular stimulates creative thought. The HDL-64E Laser Rangefinder manufactured by Velodyne, boasts an amazing set of specifications. The HDL-64E has the ability to quickly and accurately gather data at a rate of 1.333 million points per second!  That is incredible. The sensor head can rotate up to 900 RPM with a vertical window of 26.8 degrees. The range is from 50m for pavement and up to 120m for cars, foliage, etc. The resulting data provides a robust, 3D point cloud that is akin to seeing with the human eye. The human eye has the benefit of the brain to process what it sees.  Similarly, a computer and processing software serves this purpose for the LiDar point cloud. The computer power and software inhales the point cloud post processing the data. LiDAR can be hindered by dust but far less than imaging sensors and darkness is not an issue. As this technology evolves, it becomes more feasible to see this type of sensor as a machine control sensor. Consider this possibility.

 

Crystal Ball
Lets consider placing a sensor such as the HDL-64E on the roof of a dozer. By referencing a static object in the field of view, dozer blade movement, pitch, roll and yaw, could be accurately realized. Perhaps monitoring could be enhanced by a reflective target(s) placed on the blade to create additional contrast from other items in the field of view.

Another benefit would be less/no cables while eliminating components where damage is more likely. For example, GNSS receivers, antennas and axial sensors placed and cabled on the blade.

Other possible features could include “seeing” past the blade and monitoring the existing surface in real time. This has the potential to offer much more accurate measurements over GNSS and existing sensor technology. Truly a touch-less machine control system offering accurate, real time topo and grid updates. d the machine. The on board computer and software application would be doing some pretty heavy lifting with regards to data processing to realize real-time cut/fill relative to the design surface but with todays powerful, smaller computers, this is not a stretch.

Other Applications
Safety - Asset Avoidance
Autonomous Vehicles


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Reference Links and Additional Information.

LiDAR News - Gene Roe
Defense Advanced Research Projects Agency (DARPA)
The LiDAR Solution - Lighting the way to more accurate surface geometries for grading and staking - Jeff Winke
Mapping the world in 3D - Brent Schwarz
Radiohead - House of Cards - music video produced with LiDar only, no cameras

Additional LiDAR/Scanner Manufacturers

Leica

Topcon

Trimble

Riegl Laser Measurement Systems

Faro

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