Robust digital controller for skid-steer machine
AssigneeAGCO International GmbH
InventorBenjamin Fernando Fernandez Guzmann
Life of this patent
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Abstract
An autonomous skid-steer machine includes a chassis, a plurality of ground engaging elements supporting the chassis on a ground surface and one or more computing devices for controlling movement of the machine. The one or more computing devices are configured to generate a control signal for controlling operation of at least some of the plurality of ground engaging elements, the control signal being generated according to a control algorithm incorporating tuning parameters, and to automatically determine the tuning parameters in real time during operation of the machine such that the control algorithm is always optimized for a current speed of the machine. The tuning parameters are found using the machine's current speed, a natural frequency value and a damping value.
Claims13
An autonomous skid-steer machine for performing agricultural operations, the machine comprising—
- a chassis;
- a plurality of ground engaging elements supporting the chassis on a ground surface;
- one or more computing devices for controlling movement of the machine, the one or more computing devices configured to—
- generate a control signal for controlling operation of at least some of the plurality of ground engaging elements to cause the machine to move in a forward direction and to turn the machine, the control signal being generated according to a control algorithm incorporating tuning parameters, and
- automatically determine the tuning parameters in real time during operation of the machine such that the control algorithm is always optimized for a current speed of the machine, wherein the tuning parameters are found using the machine's current speed, a natural frequency value (ω0) and a damping value (ζ),
- wherein the natural frequency value (ω0) determines reactiveness of the machine as it responds to navigational errors,
- wherein the damping value (ζ) determines overshoot of the machine as it responds to navigational errors,
- wherein the natural frequency value (ω0) and the damping value (ζ) are determined specifically for the characteristics of the autonomous skid-steer machine and using one or more sensitivity functions, the one or more sensitivity functions including—
- a first sensitivity function (Syp) corresponding to a relationship between an output of the system y(t) and disturbances in the system p(t),
- a second sensitivity function (Sup) corresponding to a relationship between a steering input u(t) and the disturbances in the system p(t),
- a third sensitivity function (Syb) corresponding to a relationship between an output of the system y(t) and system noise b(t), and
- a fourth sensitivity function (Syv) corresponding to a relationship between the output of the system y(t) and disturbances on a plant input v(t).
Dependencies are inferred from the claim text.