Making a LiDAR – Part 1

LiDAR Mechanical Aspects

By: David
Principal Consultant, Data Exploration

8th April 2019

3 minute read

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LiDAR mechanical aspects


In concept, a LIDAR scanner is a rather simple way of capturing 3D scans of a physical environment, and in this series of 5 blogs I’ll take you through my various thought processes in building a working LIDAR prototype. In our LIDAR prototype, we will see if we can use a GARMIN laser range finder sensor to build a working LIDAR. We will spin the range finder on its azimuth, and after each complete revolution, we will nudge it slightly to point upwards at increasingly steeper angles. At the same time, we will continually capture the measured distance data to the target. When the scan is complete we will have a data set called a point cloud that represents the distance from the LIDAR to every point in the room and that’s just perfect for rendering on an Oculus Rift VR headset. But, before we get ahead of ourselves, we have a few mechanical problems to solve first.


If you’ve seen the press hype about 3D printed firearms you might be surprised to hear me express 3D printer disappointment, and In fact, you might have expected a 3D printer to be my perfect “drawing board to the physical word” prototyping tool. But, I’d say the reality is rather different. It’s hard to say if my scepticism comes from the PLA filament unravelling, the shrinkage leaving questionable tolerances, the poor finish, or the print times in excess of 12 hours. Either way, I’m unconvinced by the results of consumer and light industrial 3D printers. So, we’ll build our LIDAR parts old school with a manual lathe and mill. (There is just one niggling point and very important points that we will come to later where we use a 3D printer to enable everything!) I should also add that my industrial design colleagues producing beautiful flowing curved case works may have a very different opinion to myself. For them, 3D printing comes into its own.

We’ve also got an electrical wiring problem to solve, and that’s because we need to get power and data to our range finder without our wires getting twisted. We’ve got three obvious choices on how to do this; we can spin 360 degrees and then unwind the wires by spinning the other way, or we can build a complicated inductive power system with RF\optical to carry data (no wires to twist), or we can use a slip ring (a slip ring works just like the brushes on an electrical motor). The first solution is ugly and will slow the scan down with all the stopping and starting. The second solution sounds robust, but it’s a design exercise in itself that adds unnecessary burden to our budget. Ideally, we’d rather not have that for a prototype. The third solution is quick, very low cost, but will eventually fail as the slip ring brushes degrade. None the less, even a low-end slip ring is rated 5,000,000 revolutions, which is more than enough for our prototype.


Our slip ring will need to fit through the body of a rotating shaft, and it needs to be mounted with screws that clamp the slip ring flange onto the shaft. There isn’t anything we can do to change the slip ring dimensions, so follow it through and the shaft diameter comes in at around 22mm. We’ll need the shaft to fit through bearings, and we want the shaft to rotate. We’ll do that with a timing belt and timing gear around the shaft.

In concept, a LIDAR scanner is a rather simple way of making 3D scans of a physical environment. In our LIDAR prototype, we will see if we can use a GARMIN laser range finder sensor to build a working LIDAR. We will spin the range finder on its azimuth, and after each complete revolution, we will nudge it slightly to point upwards at increasingly steeper angles. At the same time, we will continually capture the measured distance data to the target. When the scan is complete we will have a data set called a point cloud that represents the distance from the LIDAR to every point in the room and that’s just perfect for rendering on an Oculus Rift VR headset. But, before we get ahead of ourselves, we have a few mechanical problems to solve first.

If you’ve seen the press hype about 3D printed firearms you might be surprised to hear me express 3D printer disappointment, and In fact, you might have expected a 3D printer to be my perfect “drawing board to the physical word” prototyping tool. But, I’d say the reality is rather different. It’s hard to say if my scepticism comes from the PLA filament unravelling, the shrinkage leaving questionable tolerances, the poor finish, or the print times in excess of 12 hours. Either way, I’m unconvinced by the results of consumer and light industrial 3D printers. So, we’ll build our LIDAR parts old school with a manual lathe and mill. (There is just one niggling point and very important points that we will come to later where we use a 3D printer to enable everything!) I should also add that my industrial design colleagues producing beautiful flowing curved case works may have a very different opinion to myself. For them, 3D printing comes into its own.

We’ve also got an electrical wiring problem to solve, and that’s because we need to get power and data to our range finder without our wires getting twisted. We’ve got three obvious choices on how to do this; we can spin 360 degrees and then unwind the wires by spinning the other way, or we can build a complicated inductive power system with RF\optical to carry data (no wires to twist), or we can use a slip ring (a slip ring works just like the brushes on an electrical motor). The first solution is ugly and will slow the scan down with all the stopping and starting. The second solution sounds robust, but it’s a design exercise in itself that adds unnecessary burden to our budget. Ideally, we’d rather not have that for a prototype. The third solution is quick, very low cost, but will eventually fail as the slip ring brushes degrade. None the less, even a low-end slip ring is rated 5,000,000 revolutions, which is more than enough for our prototype.

Our slip ring will need to fit through the body of a rotating shaft, and it needs to be mounted with screws that clamp the slip ring flange onto the shaft. There isn’t anything we can do to change the slip ring dimensions, so follow it through and the shaft diameter comes in at around 22mm. We’ll need the shaft to fit through bearings, and we want the shaft to rotate. We’ll do that with a timing belt and timing gear around the shaft.

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