UPDATE: The company Scanse.io which produced the Scanse Sweep Scanner has ceased operations as of May, 2018. This article remains here for reference purposes.
The newly introduced Scanse Sweep Scanner is an inexpensive 2D LIDAR that is easy to interface with a NVIDIA Jetson Development Kit. Looky here:
LIDAR is much the talk in robot navigation, especially in the autonomous driving arena. It comes in three flavors. The first is usually called 1D, a single laser and receiver measuring the distance of a single point in front of the sensor.
The second is called 2D, and conceptually consists of a single laser/receiver sensor spinning in a circle. Mechanically this may mean that the sensor is mounted on an encoded motor, or a spinning optical device such as a mirror spins above a stationary sensor.
The third is 3D, which provides a surrounding view from all angles. This is usually what people think about when talking about LIDAR on autonomous vehicles. Such devices usually are implemented with a sensor placed underneath a spinning mirror. The mirror not only spins, but also moves in the Y-plane simultaneously. ‘Inexpensive’ professional versions start around $8000 USD and quickly escalate to over $100,000.
There have been many companies working towards bringing higher resolution LIDARs of different types, including fully solid state 3D versions, to market at a consumer price point over the last few years. As of this date, none are shipping.
The Scanse Sweep is a 2D LIDAR. A laser sensor is mounted on an encoded motor, which spins around providing a 2D view. The data is provided over a serial port. You can read the specs on the Scanse page.
The Sweep Scanner is currently around $350 USD, which makes it affordable in the world of LIDARs. At the same time, you will need to manage your expectations. This device running at maximum speed of 10 Hz and sample rate of 1000 samples per second are well below that of even the next competitor up the LIDAR wrung, the RP-LIDAR A2. For a comparison of the two, see: Comparing low-cost 2D scanning Lidars on DIY Robocars.
At the same time, you realize that just a couple of years ago there were no real entries at this price point. Many DIYers were taking apart Neato robot vacuum cleaners to cannabilize a less capable LIDAR unit, but that’s about it.
The actual Sweep Scanner is well thought out. Mounting the device is simple using 2.5M screws and there are two different ports at different orientations which may be used to interface the serial port to USB using a FTDI serial to USB converter. On RACECAR/J, the Scanse plugs into a USB hub which is in turn connected to the onboard Jetson.
As usual, JetsonHacks provide a repository on Github called installSweep which provides convenience scripts for installing both the SDK and the ROS wrapper. The SDK must be installed before the ROS Wrapper.
$ git clone https://github.com/jetsonhacks/installSweep
$ cd installSweep
The SDK will be installed in directory ~/sweep-sdk.
If you want the ROS wrapper installed, you need to have an initialized Catkin Workspace. Then:
$ cd ~/installSweep
$ ./installSweepROS.sh [catkin workspace name]
This will clone the repository, run rosdep to install missing dependencies, and then catkin_make the package. The name of the package is ‘sweep_ros’.
- The Scanse Sweep Scanner is connected to an AmazonBasics 7-Port, USB 3.0 Hub. The USB Hub is connected to a Jetson Development Kit.
- USB Autosuspend is turned off. USB Autosuspend usually powers down USB ports to conserve power.
For a freshman effort, the Sweep Scanner is surprisingly well done. The device itself is well though out, and the software support with basic libraries easily available via Github allows for easy integration into applications. The ROS wrapper is an added bonus. Whether the Sweep meets the performance goal for a given project needs to be thought about, but it is nice to have an low cost entry point into the LIDAR world.