The LR4 interface board adds a USB port to an off-the-shelf, inexpensive laser distance measurement tool, allowing software to control the rangefinder and automate data collection.
For years scientists, engineers, and experimenters have wrestled with ultrasonic or IR distance sensors that give mediocre results. The LR4 makes possible high precision, true time-of-flight laser range finder technology in an affordable package.
Range: 0.1 to 50 meters
Accuracy: 3mm max / 2mm typical
Power Consumption: < 200mA (USB bus powered)
Measurement Rate: 0.4 to 2.5 Hz
When attached to a simple Fluke 414D laser measurement tool (available Fry's or Amazon.com for around $125), the LR4 forms a USB attached laser rangefinder ideal for industrial or robotics use.
Laser rangefinders are vastly superior to ultrasonic rangefinders, which suffer from problems caused by their wide beam pattern. Narrow objects often appear much wider than they are because of the 20 to 30 degree sense angle of ultrasonic. IR distance sensors aren’t even in the same league as the LR4. IR sensors, such as those based on the Sharp GP2D12, have limited range (around 3 feet), non-linear output, and are very imprecise.
When you order the LR4 you will receive a kit that includes the two flex cables that are needed to connect the LR4 to a Fluke 414D.
Here’s how it works
Purchase an LR4 online from Porcupine Labs.
Purchase a Fluke 414D (many online sources).
Open up the 414D and unplug the 414D’s LCD display and keypad.
Clip the 414D's battery wires and plug them into the LR4. (no soldering!)
Plug the LR4 in place of the LCD and keypad.
Now attach the LR4’s USB cable to a USB port and begin using your precision range finder.
This video demonstrates the assembly process.
This video shows off some of the features of the older LR3 and new LR4 using the demo software (available below). The video was made before we designed the LR4, but all of the features mentioned in the video apply to the LR4 because the LR4 is software compatible with our previous LR3 board.
The LR4 is a standard HID (Human Interface Device) class peripheral. This means that most operating systems have built in driver support for the LR4. For example, Microsoft Windows allows applications to read data directly from HID devices - no messy drivers to write.
The LR4 supports both continuous and one-shot measurement modes. While in continuous mode, the LR4 performs up to two distance measurements per second. Distance data and status information is returned in simple 8-byte packets.
The LR4 also supports a "keyboard emulation" mode which simulates key presses on a keyboard. This allows the LR4 to "type" distance measurements directly into standard application programs such as spreadsheets and word processors.
Fluke's new 414D laser distance meter has much better range (50m) over their previous comparable product, the 411D (30m). To accomplish this, Fluke has decreased the measurement rate. Under good conditions the 414D will produce a measurement every 400ms. If the range to the target gets above 15 or 20 meters, the measurement rate will decrease. Targets with poor reflectivity such as a dark or bumpy surface will also cause measurement rate to suffer. The slowest measurement rate that we have seen from the 414D is about 23 measurements per minute or about 0.4Hz.