Autonomous lawn mower competition encourages students to practice 'engineering'

　　Students at Western Reserve University designed an autonomous lawn mower that cuts grass by defining a mowing path and avoiding obstacles. The team combined sensors, control algorithms, system control, and image processing for engineering practice. In June 2010, the team won first place in the 7th Institute of Navigation (ION) Autonomous Lawn Mower Competition. Here's how they did it.

　　Students were asked to quickly assemble the engineering components needed for robot design within a semester. The robot's control system requires the connection of compatible components, including the combination of sensors and actuators, control algorithms, and advanced image processing. NI LabVIEW software provides students with a complete engineering practice development environment.


　　Hardware API


　　Using NI 9401 C Series digital I/O modules, the team used encoders to measure speed and position. By tightly integrating with the hardware, they were able to quickly acquire data from multiple sensors

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　　To determine the robot's state, the team used a mathematical function called Kalman filtering. They used the built-in mathematical functions in LabVIEW to perform inline analysis on the data measured by the sensors. [page]

　　Custom User Interface


　　To detect obstacles, students use NI Vision software to acquire, process, and display images from the camera. Using the user interface, students identify obstacles by color and visual texture.

　　Deployment Goal


　　The robot uses an embedded real-time processor and field programmable gate array (FPGA) for advanced control. A modular I/O system interfaces with sensors and actuators for real-time image processing.

　　Technical Approach


　　Students take advantage of FPGA technology to collect timing-critical data to control the robot. Compared with VHDL, LabVIEW graphical programming simplifies the complexity of embedded FPGA programming.

　　Design Method


　　To integrate existing code, students used the Call Library Function Node to merge algorithms developed in ANSI C into LabVIEW programs. Combining multiple programming methods in LabVIEW, students achieved code reuse and development optimization.