Product category:
Position, speed and torque measurement
News Release from: Autonnic Research | Subject: RoboMower
Edited by the Processingtalk Editorial
Team on 13 April 2007
RoboMower gets its magnetic direction
right
Fluxgate based magnetic field sensors are at the heart of the guidance systems used for the robotic lawnmower called RoboMower: the grass stripes must be parallel to within one degree
RoboMower, the world-leading brand of self-guided lawnmower, relies on an Autonnic AR35 floating core fluxgate at the heart of its guidance system The fluxgate output provides the continuous directional information used to maintain the mower travel direction and course within the marked boundary of the lawn
This article was originally published on Processingtalk on 15 Jun 2004 at 8.00am (UK)
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Manufacturer Friendly Robotics requires especially tight control over straight-line performance to minimise wandering to within one degree.
Controlling absolute direction of travel allows a little more tolerance.
Friendly Robotics considered several different technologies for the guidance system before opting for fluxgates.
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"We went for fluxgates because they give us the accuracy and, with a gimballed system, they provide a solution that is cost-effective because it is relatively straightforward to implement," explains Shai Abramson, Vice President, Research and Development.
Inherent compensation for the dip angle of the earth's field is essential and Friendly preferred the liquid gimbal provided by the floating core to mechanically gimballed alternatives.
"When we originally approached Autonnic they were most co-operative in customising the design to match our specification," says Abramson.
The AR35, tilt-compensated fluxgate used is common to that in the OEM compass module offered by the Autonnic Subsystems Division, Fluxgate World.
This is designed for a number of applications including robotic guidance.
The Fluxgate World 'bare-board' compass modules offer product manufacturers a fully-interfaced sensor for the earth's magnetic field.
They include full analogue and digital embedded controller hardware to provide heading data with a 0.1 resolution and 0.2 degree accuracy and can include auto-calibration.
Whilst the floating core magnetometer provides full 2-axis tilt-compensation providing constant output by resolving only the horizontal component of the earth's magnetic field, where this is not required, costs can be reduced by opting for a fixed core sensor.
Three versions of the Autonnic range of floating core magnetometers cater for tilt angle ranges of +/-20 , +/-35 and +/-45 respectively; normally undamped they can also be supplied with varying degrees of viscous damping.
With its focus on the design, development, manufacture and sales of Home Robotics, Friendly Robotics has established a world market lead.
"It has taken time to overcome the early market scepticism," Abramson accepts: "but worldwide sales are now showing impressive growth; as every new sale helps demonstrate the effectiveness of our technology and the performance of our machines, so demand grows exponentially," he enthuses.
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