Display of Stability Data for Safe Tractor Operation
D.J. Murphy and H.J. Sommer
Major Accomplishment FY2.1 - A second-generation overturn sensor using an Atmel AVR
microprocessor and MEMS accelerometer was refined. Total cost of electronic components was held to
under $50. One major effort in this task was to develop an exact thermal compensation method to prevent
signal drift by the MEMS accelerometer due to different ambient temperatures. All previous
implementations of these accelerometers have required expensive temperature controlled enclosures.
Major Accomplishment FY2.2 - The second-generation overturn sensor was interfaced to a standard
CAN bus architecture currently used in most automobiles. The CAN bus allows seamless communication
between a variety of sensors, actuators and controllers within vehicles and is just starting to appear on
new model agricultural tractors. This task will allow the overturn sensor system to be easily integrated
into electronics for new tractor designs.
Major Accomplishment FY2.3 - Commercial display units were evaluated based on cost, interface
requirements and ergonomic perception. Two units (a simple bi-color LED grid and a miniature color
LCD screen) were selected. The LED grid has been fully integrated with the second-generation overturn
sensor via the CAN bus for full size tractor overturn tests described below. Circuit designs for the LCD
unit have been developed.
Major Accomplishment FY2.4 - The second-generation overturn sensor, CAN bus interface and LED
grid display were tested and validated on July 16 and August 4 during side overturn tests at the PSU
Larson Agricultural Research Center. These tests used a full size remote umbilical controlled tractor with
a rear deck mower as shown in Figure 1. They are the first documented overturn tests purposefully
conducted with an attached implement. PSU staff are shown checking the overturn sensor and
downloading scientific data after the tractor has been judged to have come to rest in a stable but
overturned configuration.
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Figure 1 - Side Overturn Test with Rear Deck Mower Using Remote Umbilical Control Tractor
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