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Robot that uses only Magnetic Field to Navigate

11 August 2011 No Comment

Researchers at Utsunomiya University have developed an autonomous mobile robot that uses only environmental magnetic fields to navigate outdoors with reliable accuracy. Professor Koichi Ozaki was kind enough to invite us for a demonstration on a 1 km course around the university campus.

Why navigation using magnetic fields? It is pretty difficult for autonomous robots to successfully navigate in outdoor environments. There are many factors to consider; weather, illumination, change in vegetation, these all change a robot’s perception of an environment. GPS is considered the most feasible method for acquiring positioning data. But GPS is also prone to errors such as signal delays and multipath phenomenon, where a GPS signal is reflected off large objects such as tall buildings before it reaches the receiver. As a means of providing additional methods for navigation the Utsunomiya University researchers started looking into using geomagnetic profiles.

Drawing inspiration from migratory birds’ use of magnetic fields to find their way home, the group modified their robot ERIE to a geomagnetic navigator. This robot consists of a control computer, a laser ranger finder (obstacle avoidance), a magnetic sensor, 2 driving wheels and 2 coasters to rear. Before the robot can navigate and area successfully the area’s magnetic field must first be mapped to a database. This is done by controlling the robot with a joystick while it records it’s current position along with a reading of that area’s magnetic field. Once the database is complete the robot will be able to find it’s around the mapped area all by itself (monitored by humans of course).

During the demo run I was impressed at how accurately the robot followed the course as it cruised around campus at 0.5 meters per second. There were a few check points along the way in the form of manhole covers. These served as easily recognizable landmarks to the robot because they have a stronger magnetic field than their surroundings. It also dealt really well with obstacles. We encounter a few pedestrians and many cyclists along the way. When the ERIE’s path as obstructed, it still was able to get back on course. Indoors proved challenging for the bot as it moved a lot more slowly swerving for wall to wall in corridors and sometimes stopping for a moment. This is because the fluctuating magnetic field of electrical wiring within the building affects the magnetic sensor. The robot was though still able to complete the course saying “Goal!” as it passed the finish line.

The researchers hope magnetic navigation can be used along side other methods as a means of making outdoor robotic navigation a lot more accurate and reliable. They plan to use ERIE as a means of transportation in the field of agriculture, possible combined which their strawberry picking robot.