Abstract: A mobile transmitter transmits a transmission signal from a vehicle to beacons. An estimator determines elapsed times for corresponding propagation paths between the vehicle and the beacons. Each propagation path includes at least one of a first propagation duration of a transmission signal and a second propagation duration of a return signal. A compensator compensates for noise or measurement error associated with a corresponding propagation path by invoking a linear fit scheme. The linear fit scheme applies a generally linear fit over fixed intervals of noisy measurements such that the noisy position measurements generally conform to a linear portion of a path plan of a vehicle. A data processor estimates a position of a vehicle at a confluence or intersection of the position curves or temporal curves based on elapsed times for the propagation paths.

Abstract: A method and system for determining the position of a vehicle comprises a transmitter or transceiver for transmitting a transmission signal from a vehicle to beacons associated with the work area. A data processor determines an elapsed time including at least one of a first propagation duration and a second propagation duration. The first propagation duration refers to a propagation time of the transmission signal from the vehicle to the particular beacon; the second propagation duration refers to a propagation time of a return signal from the particular beacon to the vehicle. A compensator compensates for the following associated with the transmitter and the particular beacon: bias delay, noise, and measurement error. A data processor processes the elapsed times into corresponding position curves or temporal curves to estimate a position of a vehicle at a confluence or intersection of the position curves or temporal curves.

Abstract: A time estimator determines a first aggregate elapsed time between the transmission of the first transmission signal to a first beacon and receipt of a return signal, a second aggregate elapsed time between the transmission of the first transmission signal to a second beacon and receipt of a return signal, and a third aggregate elapsed time between the transmission of the first transmission signal to a third beacon and receipt of a return signal. A bias compensator compensates for bias delay associated with at least one of the first transmitter, the first beacon, the second beacon and the third beacon. A converter converts the first aggregate elapsed time, the second aggregate elapsed time, and the third aggregate elapsed time into position curves. A data processor estimates a position of the vehicle at a confluence or intersection of the position curves.

Abstract: A transmitter at a lead vehicle transmits a first transmission signal toward a first beacon and a second beacon associated with a following vehicle. A data processor or estimator determines a first propagation time associated with the first transmission and the first beacon and a second propagation time associated with the first transmission and the second beacon. A vehicle controller controls a heading of the following vehicle to maintain a first distance substantially equal to a second distance (i.e., first propagation time substantially equal to a second propagation time) or a first distance that deviates from the second distance by a predetermined maximum amount.

Abstract: A first location determining receiver determines a first location estimate of a vehicle. The first location determining receiver is associated with satellite beacons. A second location determining receiver determines a second location estimate of a vehicle. The second location determining receiver is exclusively associated with terrestrial beacons. A selector selects the first location estimate of the vehicle as a preferential location in accordance with an initialization scheme for the vehicle in a work area. A filtering module applies a first weight to a first location and a second weight to the second location to derive a weighted estimate as the preferential location upon satisfactory completion of the initialization scheme.

Abstract: A mobile transmitter transmits a transmission signal from a vehicle to beacons. An estimator determines elapsed times for corresponding propagation paths between the vehicle and the beacons. Each propagation path includes at least one of a first propagation duration of a transmission signal and a second propagation duration of a return signal. A compensator compensates for noise or measurement error associated with a corresponding propagation path by invoking a linear fit scheme. The linear fit scheme applies a generally linear fit over fixed intervals of noisy measurements such that the noisy position measurements generally conform to a linear portion of a path plan of a vehicle. A data processor estimates a position of a vehicle at a confluence or intersection of the position curves or temporal curves based on elapsed times for the propagation paths.

Abstract: A frame of a mower supports wheel assemblies, a propulsion unit, and a mowing deck. Each wheel assembly is associated with a corresponding wheel, a corresponding electrical steering motor, and a corresponding electrical drive motor. A controller controls a direction of orientation of the corresponding wheel via the corresponding electrical steering motor. Further, the controller controls the application of electrical energy to the corresponding drive motor consistent with maneuverable movement of the mower. The propulsion unit is capable of rotating at least one cutting blade. A mowing deck houses the at least one cutting blade. The mowing deck has indentations to provide a spatial zone for the plurality of wheel assemblies.

Abstract: A method for configuring a local positioning system comprises orienting a survey antenna coextensively with a primary beacon associated with a work area. A transmitter or transceiver transmits a first transmission signal from the survey antenna. A receiver or transceiver receives the first transmission at one or more secondary beacons associated with the work area. A data processor determines first elapsed times from the transmission time of the first transmission signal to at least the arrival time at respective corresponding secondary beacons. Each of the first elapsed times falls within a filtering time window, or satisfies an edge timing criteria of the coded signal, or both to reduce multi-path error. The first elapsed times are converted into a first position in at least two spatial dimensions for the primary beacon.

Abstract: A frame of a mower supports wheel assemblies, a propulsion unit, and a mowing deck. Each wheel assembly is associated with a corresponding wheel, a corresponding electrical steering motor, and a corresponding electrical drive motor. A controller controls a direction of orientation of the corresponding wheel via the corresponding electrical steering motor. Further, the controller controls the application of electrical energy to the corresponding drive motor consistent with maneuverable movement of the mower. The propulsion unit is capable of rotating at least one cutting blade. A mowing deck houses the at least one cutting blade. The mowing deck has indentations to provide a spatial zone for the plurality of wheel assemblies.

Abstract: A method for operating a mower comprises defining a reference axis of rotation at a desired point along a path segment of the mower. A controller orients wheels of the mower generally tangentially to a circular region about the reference axis. A drive motor applies rotational mechanical energy to one or more of the wheels to rotate the mower by a desired angular amount about the reference axis.