High accuracy products and technologies to measure the distance or to detect objects are associated with laser technology. All of these technologies are used in robotic applications where errors should not exceed few millimeters in different conditions and environments.

Associated with futuristic technologies from science fiction movies and books, the laser technology increases its presence in robotics especially for autonomous robots like self-driving vehicles.

Used to measure the speed, acceleration and distance to objects, these laser sensors have a simple process of running. The operation mode includes a pulse of light in the range of the sensor and measure the time when the pulse is received back. Applying simple mathematical formula the distance is calculated.

The range of laser sensors varies from meters and up to hundreds of meters while some of these can keep the accuracy at high level.

Several projects use laser sensors including self-driving vehicles from DARPA competition that uses laser technology for navigation to sense the terrain and to detect the obstacles around vehicles.

In this article, I made an overview of laser sensors designed for robotic applications with accuracy in measurement.

Parallax

Based on Parallax’s Propeller microcontroller, the Parallax laser sensor is a good alternative for projects with limited budgets and with specifications that include a range between 15 and 122 centimeters. This sensor is the result of collaboration between Parallax and Grand Idea Studio company who design and built over time innovative electronic products that today are available on the market.

Inside, the laser sensor has a CMOS camera and a laser diode system capable to determine the distance using trigonometry between the sensor to the object. Into robotic applications the sensor could be integrated to measure the distance, for object detection, or for counting items.

Features:

• Range: 15-122 cm (6-48 in);
• Power consumption: 5 VDC, 150 mA;
• Accuracy: 3% average error, less than 5% peak error;
• Maximum detection range: 240 cm (8 ft);
• Sample rate: 1 Hz;
• Communication interface: serial, auto-detect 300-115.200 baud;
• Operating temperature: 0-50 degrees C (32-122 degrees F)

Hokuyo URG-04-LX-UG01

With a complex name, something like a password, Hokuyo releases on the market one of the most accurate and lightweight laser module with a scanning range between 2 and 560 cm. This sensor is designed to be used in mobile robotic applications where the requirements include a resolution of 1 millimeter and view angle of 240 degrees.

Features:

• Range: 2-560 cm (0,79-220 in);
• Angle of view: 240 degrees;
• Resolution: 1 mm distance, 0,36 degrees angular;
• Accuracy: 6-100 cm – 30 mm, 100-409 cm – 3%;
• Maximum detection range: 560 cm (220 in);
• Command system: SCIP 2.0;
• Power consumption: 5 VDC, 2,5 W;
• Communication interface: USB 2.0/1.1, mini-B connector;
• Weight: 160 g;
• Operating temperature: -10 – +50 degrees C (14-122 degrees F);

Hokuyo UBG-05LN

Compact design and heavy-duty applications are two main characteristics that describe broadly the UBG-05LN laser sensor. Scanning area is between 0.1 to 5 meters in length while in width the area is set to a maximum 4 meters. The sensor has a wide range of scanning with a scanning angle of 180 degrees. Measuring the distance from an object and calculating its steep angle the sensor could set the coordinates of the object detection in the environment.

UBG-05LN is used almost for robotic applications that require a long distance obstacle detection and for a good setup it has available 31 modes for area detection.

Features:

• Range: 0,1 to 5 m in length and 4 m wide;
• Angle of view: 180 degrees;
• Accuracy: less than 1 m – 20 mm, over 1 m – 2%;
• Repeatability: less than 1 m – 10 mm, over 1 m – 2%;
• Hysteresis: 6,25%;
• Maximum detection range: 5 meters (16,4 ft);
• Power consumption: 24 VDC and 150 mA (supports between 18 and 30 VDC);
• Weight: 180 g (260 g with cable);
• Operating temperature: -10 – +50 degrees C (14-122 degrees F);

Loke LMC-J-0040

LMC-J-0040 is primarily used for industrial robotic applications requiring a high accuracy and various possibilities to interface the output data. The analog output rate has a frequency of 10 Hz while the analog output is between 4 to 20 mA. For digital interfacing the sensor is equipped with RS 232 or RS 422.

One of the most important feature of this sensor is the measuring range with values between 35 meters and up to 150 meters. Depending on conditions LMC-J-0040 can have an accuracy between 2 and up to 3 millimeters.

Features:

• Range: 0,2-35 m (0,66-115 ft);
• Accuracy: 2-3 mm;
• Repeatability: 0,5 mm;
• Measure rate: 5-10 Hz;
• Maximum detection range: up to 150 m (492 ft) with special reflective surfaces;
• Power consumption: 10-30 VDC, 1,5 W;
• Communication interfaces: RS232/RS422 with selectable data output, 9600 baud, analog 4-20 mA;
• Housing protection rating: IP65;
• Weight: 850 g;
• Operating temperature: -10 – +50 degrees C (14-122 degrees F);

Loke LMC-J-0050

Precise and robust are the best chosen two words that describe this laser sensor. With millimeter accuracy and protection system the sensor is designed for industrial applications in places less friendly with humans. Without additional measurement equipment the sensor can detect the motion and the contour of the objects from its scanning range.
Features include Ethernet, WiFi, Bluetooth connectivity as well as analog interfaces and RS232/RS422 digital interface.

Features:

• Range: 0,2-30 m (0,66-115 ft);
• Accuracy: 2-3 mm;
• Repeatability: 0,5 mm;
• Measure rate: 5-10 Hz;
• Maximum detection range: up to 150 m (492 ft);
• Power consumption: 10-30 VDC, 1,5 W;
• Communication interfaces: RS232/RS422/RS485 with selectable data output, ProfiBus, SSI, analog 4-20 mA, Ethernet, WiFi, Bluetooth, CANopen, CAN 2.0;
• Housing protection rating: IP66;
• Weight: 4,3 kg;
• Operating temperature: -10 – +50 degrees C (14-122 degrees F);

Hokuyo UBG-04LX-F01

Hokuyo build advanced sensors and is evident that UBG-04LX-F01 is one of the most powerful laser sensors from company range. UBG-04LX-F01 was designed to be used especially for autonomous robots that requires an increased speed of measurement. Features include a scanning speed of 28 ms and a detection range between 2 to 560 centimeters. Like all laser sensors from Hokuyo, this one has the same characteristics like high resolution and a high accuracy.

Features:

• Range: 2 to 560 cm;
• Power source: 12VDC;
• Angular Resolution: 0.36°(360°/1,024 steps);
• Accuracy Nominal Range: 6 to 100 cm – 1 cm, 100 to 409 cm – 1% of distance;
• Scan Time: 28 ms/scan;
• Interfaces: USB 2.0, RS-232C (19.2k, 57.6k, 115.2k, 250k, 500k, 750kbps);
• Ambient temperature and humidity: -10 to +50 degrees C, less than 85% RH;
• Impact Resistance: 196 m/s2, 10 times in X, Y and Z direction;
• Weight: 260g;

Hokuyo UTM-30LN/30LX

The series of UTM laser sensors continues with UTM-30LN/30LX designed to scan and detect objects for up to 30 meters at a view angle of 270 degrees. This is one reason that the sensors are almost used for outdoor applications like autonomous vehicles. Like many other laser sensors from Hokuyo, UTM-30LN/30LX has implemented a high accuracy and repeatability in hard-working conditions.

Features:

• Range: 0.1 to 30 m (Max. 60m) and 270°;
• Power consumption: 12VDC, nominal 0.7 A, peak 1 A;
• Light source (for 30LX): Semiconductor laser diode(?=905nm);
• Accuracy: 0.1 to 10 m – 3 cm, 10 to 30m – 5 cm;
• Angular Resolution: 0.25° (360°/1,440 steps);
• Scan Time: 25 ms/scan;
• Sound level: Less than 25 dB;
• Connections: Power and output – 2m flying lead wire, USB – 2 m cable with type-A connector;
• Ambient temperature and humidity): -10 to +50 degrees C, less than 85%RH (without dew and frost);
• Impact Resistance: 196 m/s2, 10 times in X, Y and Z direction;

Acuity SRI500

With 3D capabilities, the SRI500 is one of the most popular laser sensors used in robotic applications that include mapping. More accurately, this is the best sensor that can be used for a self-driving car. Features include a distance for detection up to 152 meters in stationary or for mobile platforms. Combining vertical and horizontal information the sensor builds a 3D map of the environment.
Another great feature includes the possibility to be programmed for reversing the direction if it is used in a specific region many times.

Features:

• Maximum Range: 85% Reflectance Lambertian Surface 152 meters (500 feet);
• Minimum Range: 1.5 meters (5 feet);
• Scan Angles: Azimuth ± 300, Elevation ± 65;
• Scan Speed: Vertical: 500 lines/s max, Horizontal: 1000 degrees/s max;
• Range Accuracy: 2.4 cm;
• Laser Wavelength: 905 nm;
• Average Laser Power: < 1 mW;
• Laser Interlock: Vertical scan mirror encoder;
• Laser Spot Divergence: 2 millirad H × 0.5 millirad V;
• Optical Aperture: 2″ × 8.5″;
• Scan Motors: Long life brushless DC;
• Power: 50-500 W (scan pattern dependent) at 12-28 VDC;