1.2 Calculation of Data
The Incline Controller utilizes linear-actuators with built-in feedback potentiometers. Each actuator
contains an electric motor, which turns an ACME ball-screw through a gear transmission. The ACME ball-
screw is threaded into a rod which extends outside of the actuator assembly. The position of the rod is
sense by the resistive potentiometer. The potentiometer is incorporated into an electronic circuit whose
output is in direct proportion to the position of the rod. The Incline Controller employs an on-board
microcontroller with many faculties:
12-bit analog-to-digital (A/D) converter.
High-resolution 32MHz system oscillator.
32-bit floating-point arithmetic.
Up to 9th-order polynomials for feedback linearization.
Likewise, there are various other circuits which monitor the status of the linear-actuators that can halt their
operation automatically or at the user’s request.
1.2.0 Angle of Inclination
At the factory, the incline apparatus is setup on a flat and level surface. Utilizing the Columbus
Instruments’ Incline Sensor (electronic inclinometer with 0.01° resolution), the extremes of the range of
inclination and zero are discovered. These three data points are then linked to the exact positions of the
each linear-actuator’s feedback signal as measured by the A/D converter circuitry. Along with a
characteristic polynomial equation (based upon the geometry of the incline apparatus) the controller
calculates the necessary position of each linear-actuator to drive the incline apparatus to the desired angle
of inclination.
1.2.1 Rate of Change of the Angle of Inclination
The 32MHz system oscillator is used to derive a 1-millisecond clock signal. Based upon 16-bit fractional
math, the dwell-time (in fractional milliseconds) are calculated and allowed to elapse between steps (0.1°)
of the angle of inclination.
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