TORQUE RESPONSIVE CONTROL FOR ACTIVE CASTER MOTORS FOR RIDE-ON MAINTENANCE APPARATUS

Presented is a selective active caster steering apparatus for a maintenance apparatus having a first drive unit and a second drive unit. The selective active caster steering apparatus may comprise a caster wheel frame defining a caster swivel axis and a caster spin axis; a caster wheel operationally engaged with the caster wheel frame such that the caster wheel is adapted to be steered about the caster swivel axis; and a first caster steering unit adapted to selectably apply an amount of active torque to the caster wheel about the caster swivel axis as indicated by a first formula. The first formula may determine the amount of active torque to output as a first function of one or more measured parameters.

FIELD OF DISCLOSURE

The disclosed subject matter pertains to apparatuses and methods for steering a powered maintenance apparatus.

BACKGROUND

Powered maintenance apparatuses come in a variety of forms. One form of powered maintenance apparatus is powered outdoor maintenance equipment such as, and without limitation, equipment for mowing or a lawn maintenance device. It is not unusual for a powered maintenance apparatus to be of a form steerable by a user riding on the apparatus such as, and without limitation, a riding mower.

Steerable powered maintenance apparatuses sometimes use caster wheels to facilitate steerable engagement with a surface on which it operates or performs, such as a lawn or other outdoor area. A caster wheel typically is oriented about its steer axis by the forces and moments resulting from being driven and being connected to the steer axis by some caster trail. While a conventional caster does orient itself passively, under some circumstances it may be desirable to actively orient the caster wheel by application of a steering torque. It remains desirable to develop methods and apparatus to selectably and automatically apply torque to actively orient the caster wheel of an associated maintenance apparatus based on detectable parameters.

SUMMARY

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosure. This summary is not an extensive overview of the disclosure. It is not intended to identify key/critical elements or to delineate the scope of the disclosure. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

A first set of embodiments of the present subject matter may provide for a selective active caster steering apparatus for a maintenance apparatus having a first drive unit and a second drive unit. The selective active caster steering apparatus may comprise a caster wheel frame defining a caster swivel axis and a caster spin axis; a caster wheel operationally engaged with the caster wheel frame such that the caster wheel is adapted to be steered about the caster swivel axis; and a first caster steering unit adapted to selectably apply an amount of active torque to the caster wheel about the caster swivel axis as indicated by a first formula. The first formula may determines the amount of active torque to output as a first function of one or more measured parameters. The one or more measured parameters may include: a) a measurement at an input to the first drive unit of a mechanical performance parameter; b) a measurement at an input to the second drive unit of a mechanical performance parameter; c) a measurement at an output from the first drive unit of a mechanical performance parameter; d) a measurement at an output from the second drive unit of a mechanical performance parameter; e) differences in measurements at respective inputs of a first drive unit and a second drive unit of a mechanical performance parameter; f) differences in measurements at respective outputs of a first drive unit and a second drive unit of a mechanical performance parameter; g) mechanical power measurement at a powered implement of the maintenance apparatus; h) a measured torque upon the maintenance apparatus; i) time; or a combination thereof.

In some particular configurations of the first set of embodiments referenced above, the first drive unit is a first hydraulic drive motor; the second drive unit is a second hydraulic drive motor; or the first caster steering unit comprises a first hydraulic caster motor; the first function is continuously differentiable over each of the one or more measured parameters; the first function is linear, quadratic, cubic, or some other polynomial; the active torque is linearly proportional to a torque differential, where the torque differential is a difference in measurements of torque at respective outputs of a first drive unit and a second drive unit; the first function is a function of torque differential, where the torque differential is a difference in measurements of torque at respective outputs of a first drive unit and a second drive unit, angular velocity of a shaft of the first hydraulic motor, and angular velocity of a shaft of the second hydraulic motor; or some combination thereof.

A second set of embodiments of the present subject matter may provide for a powered maintenance apparatus, comprising: a first drive unit having a first drive shaft, and adapted to produce a first mechanical output; a second drive unit having a second drive shaft, and adapted to produce a second mechanical output; one or more sensors operatively engaged with the maintenance apparatus, each of the one or more sensors being adapted measure a parameter and to output data indicative of the parameter measured; a controller; and a selective active caster steering apparatus operationally engaged with the powered maintenance apparatus. The selective active caster steering apparatus may comprise a caster wheel frame defining a caster swivel axis and a caster spin axis, a caster wheel operationally engaged with the caster wheel frame such that the caster wheel can be steered about the caster swivel axis, and a first caster steering unit adapted to selectably apply the amount of active torque indicated by the first signal to the caster wheel about the caster swivel axis. In the second set of embodiments the controller may be adapted to process a first formula based on data from the one or more sensors; calculate the result of the first formula, wherein the first formula is usable to determine a first signal indicative of an amount of active torque to be applied to the caster wheel about the caster swivel axis as a first function of one or more parameters measured by the one or more sensors; and send the first signal. The one or more measured parameters may include: a) a measurement at an input to the first drive unit of a mechanical performance parameter; b) a measurement at an input to the second drive unit of a mechanical performance parameter; c) a measurement at an output from the first drive unit of a mechanical performance parameter; d) a measurement at an output from the second drive unit of a mechanical performance parameter; e) differences in measurements at respective inputs of a first drive unit and a second drive unit of a mechanical performance parameter; f) differences in measurements at respective outputs of a first drive unit and a second drive unit of a mechanical performance parameter; g) mechanical power measurement at a powered implement of the maintenance apparatus; h) a measured torque upon the maintenance apparatus; i) time; or a combination thereof.

In some particular configurations of the second set of embodiments referenced above, the first drive unit is a first hydraulic drive motor; the second drive unit is a second hydraulic drive motor; the first caster steering unit comprises a first hydraulic caster motor; the first function is continuously differentiable over each of the one or more measured parameters; the first function is linear, quadratic, cubic, or some other polynomial; the active torque is linearly proportional to a torque differential, where the torque differential is a difference in measurements of torque at respective outputs of a first drive unit and a second drive unit; the first function is a function of torque differential, where the torque differential is a difference in measurements of torque at respective outputs of a first drive unit and a second drive unit, angular velocity of a shaft of the first hydraulic motor, and angular velocity of a shaft of the second hydraulic motor; the first function is linear, quadratic, cubic, or some other polynomial; or some combination thereof.

A third set of embodiments of the present subject matter may provide for a method of providing steering force in a powered maintenance apparatus. That latter method may comprise providing a powered maintenance apparatus; measuring a parameter with each of the one or more sensors; outputting data indicative of the parameter from each of the one or more sensors to the controller; using the controller to calculate the first signal based on the parameter from each of the one or more sensors; sending the first signal to the first caster steering unit; and using the first caster steering unit to output the amount of active torque indicated by the first signal to the caster wheel about the caster swivel axis to provide steering force to the powered maintenance apparatus.

The latter powered maintenance apparatus may comprise: a first drive unit having a first drive shaft, and adapted to produce a first mechanical output; a second drive unit having a second drive shaft, and adapted to produce a second mechanical output; one or more sensors operatively engaged with the maintenance apparatus, each of the one or more sensors being adapted measure a parameter and to output data indicative of the parameter measured; a controller; and a selective active caster steering apparatus operationally engaged with the powered maintenance apparatus. The selective active caster steering apparatus may comprise a caster wheel frame defining a caster swivel axis and a caster spin axis, a caster wheel operationally engaged with the caster wheel frame such that the caster wheel can be steered about the caster swivel axis, and a first caster steering unit adapted to selectably apply the amount of active torque indicated by the first signal to the caster wheel about the caster swivel axis. In the third set of embodiments the controller may be adapted to process a first formula based on data from the one or more sensors; calculate the result of the first formula, wherein the first formula is usable to determine a first signal indicative of an amount of active torque to be applied to the caster wheel about the caster swivel axis as a first function of one or more parameters measured by the one or more sensors; and send the first signal. The one or more measured parameters may include: a) a measurement at an input to the first drive unit of a mechanical performance parameter; b) a measurement at an input to the second drive unit of a mechanical performance parameter; c) a measurement at an output from the first drive unit of a mechanical performance parameter; d) a measurement at an output from the second drive unit of a mechanical performance parameter; e) differences in measurements at respective inputs of a first drive unit and a second drive unit of a mechanical performance parameter; f) differences in measurements at respective outputs of a first drive unit and a second drive unit of a mechanical performance parameter; g) mechanical power measurement at a powered implement of the maintenance apparatus; h) a measured torque upon the maintenance apparatus; i) time; or a combination thereof.

In some particular configurations of the third set of embodiments referenced above, the first function is continuously differentiable over each of the one or more measured parameters.

To accomplish the foregoing and related ends, certain illustrative aspects of the disclosure are described herein in connection with the following description and the drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the disclosure can be employed and the subject disclosure is not intended to include all such aspects and their equivalents. Other advantages and features of the disclosure will become apparent from the following detailed description of the disclosure when considered in conjunction with the drawings.

It should be noted that the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of the figures may have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference numbers are generally used to refer to corresponding or similar features in the different embodiments, except where clear from context that same reference numbers refer to disparate features. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.

DETAILED DESCRIPTION

The following terms are used throughout the description, the definitions of which are provided herein to assist in understanding various aspects of the subject disclosure.

As used in this application, the terms “outdoor power equipment”, “outdoor power equipment machine”, “power equipment”, “maintenance machine” and “power equipment machine” are used interchangeably and are intended to refer to any of robotic, partially robotic ride-on, manually operated ride-on, walk-behind, autonomous, semi-autonomous (e.g., user-assisted automation), remote control, or multi-function variants of any of the following: powered carts and wheel barrows, motorized or non-motorized trailers, lawn mowers, lawn and garden tractors, cars, trucks, go-karts, scooters, buggies, powered four-wheel riding devices, powered three-wheel riding devices, lawn trimmers, lawn edgers, lawn and leaf blowers or sweepers, hedge trimmers, pruners, loppers, chainsaws, rakes, pole saws, tillers, cultivators, aerators, log splitters, post hole diggers, trenchers, stump grinders, snow throwers (or any other snow or ice cleaning or clearing implements), lawn, wood and leaf shredders and chippers, lawn and/or leaf vacuums, pressure washers, lawn equipment, garden equipment, driveway sprayers and spreaders, and sports field marking equipment. Operator controlled vehicles can also be implemented in conjunction with various embodiments of the present disclosure directed to apparatuses and methods for selective active caster steering.

FIG.1illustrates a diagram of an example maintenance apparatus100according to one or more embodiments of the present disclosure. Without limitation, a maintenance apparatus100can be a standing operator device in which an operator can stand on a rear portion of maintenance apparatus100to access controls105of maintenance apparatus100including to drive, steer and otherwise control maintenance apparatus100. In some non-limiting embodiments, such as the non-limiting example ofFIG.1, maintenance apparatus100may be a powered maintenance apparatus driven by an engine, a motor, or otherwise as chosen with good engineering judgment and as described further below.

Maintenance apparatus100includes rear wheels120and front caster wheels110secured to a frame of maintenance apparatus100. Rear wheels120can be drive wheels, in one or more embodiments, that are powered by a power source (not depicted) that provides mechanical power to rear wheels120with some drive unit(s). The power source can be a combustion engine, in an embodiment, including a transmission system that distributes mechanical power from the combustion engine to rear wheels120. In other embodiments, the power source can supply power to one or more drive units that comprise one or more hydraulic motors that supply mechanical power to rear wheels120. As an example, a single hydraulic motor and a transmission system can distribute mechanical power to rear wheels120. In other embodiments a first drive unit is a first hydraulic motor adapted to supply mechanical power to a first rear wheel of the rear wheel120, and a second drive unit is a second hydraulic motor adapted to supply mechanical power to a second of the rear wheels120and to a second rear wheel of the rear wheels120. In still further embodiments, the power source can be one or more electric motors that supply mechanical power to rear wheels120. For instance, a single electric motor and a transmission system can distribute mechanical power to rear wheels120, or as an alternative, a first electric motor and a second electric motor can supply mechanical power to the first of the rear wheels120and to the second of the rear wheels120, respectively.

Front caster wheels110of maintenance apparatus100can be secured to the frame thereof at least in part by way of a caster swivel axis118. In the embodiment illustrated byFIG.1, caster swivel axis118permits rotation of a caster arm116and wheel112of front caster wheels110about an axis perpendicular to or substantially perpendicular to a surface upon which maintenance apparatus100is supported (see alsoFIG.11, infra). Additionally, caster arm116includes a spin axis114facilitating rotation of wheel112within caster arm116. In the embodiment illustrated byFIG.1, caster swivel axis118can be defined by a lubricated bearing, pin, rod, or the like, that affords minimal or reduced resistance to rotation, allowing caster arm116and wheel112to rotate in response to motion of maintenance apparatus100(e.g., seeFIG.5, infra).

With additional reference toFIG.6, in various embodiments, a caster steering unit1432, such as a motor (e.g., electric motor, hydraulic motor, or otherwise as chosen with good engineering judgment), can be connected to caster swivel axis118to apply an active torque on caster swivel axis118to, at least in part, effect directional control over wheel112(seeFIGS.6-11, infra). The active torque applied by the caster steering unit1432can be in addition to a friction torque applied to caster arm116in response to movement of maintenance apparatus100(seeFIG.11, infra), and can be in the same (vector) direction or in an opposite (vector) direction as the friction torque. The active torque can be applied by the caster steering unit1432upon being activated as described herebelow, such that when deactivated no active torque is applied to caster swivel axis118and when activated the active torque is applied to caster swivel axis118.

With additional reference toFIG.14, in some embodiments, the active torque applied to the caster wheel can be activated or deactivated, manually by an associated operator or user of maintenance apparatus100by way of controls105; or by an automated process; or by a combination thereof. In some aspects, the latter automated process may be conducted using a selective active caster steering apparatus1450. In a first exemplary and non-limiting embodiment a selective active caster steering apparatus1450for a maintenance apparatus100may automatically determine and apply an amount of active torque to the caster wheel112about the caster swivel axis118. In some non-limiting aspects, a selective active caster steering apparatus1450for a maintenance apparatus100having a first drive unit1412and a second drive unit1414, the selective active caster steering apparatus1450may comprise a first caster arm116defining a first caster swivel axis118and a first caster spin axis114. In this latter first exemplary embodiment, the selective active caster steering apparatus1450may further comprise a first caster wheel112operationally engaged with the first caster arm116such that the first caster wheel112is adapted to be steered about the first caster swivel axis118. In this latter first exemplary embodiment, the selective active caster steering apparatus1450may further comprise a first caster steering unit1432, such as and without limitation selective drive motor720, adapted to selectably apply an amount of active torque to the first caster wheel112about the first caster swivel axis118as indicated by a first formula. In this latter first exemplary embodiment, the first formula may determine the amount of active torque to output as a first function of one or more measured parameters. In this latter first exemplary embodiment, the one or more measured parameters may include: a) a measurement at an input to the first drive unit1412of a mechanical performance parameter; b) a measurement at an input to the second drive unit1414of a mechanical performance parameter; c) a measurement at an output from the first drive unit1412of a mechanical performance parameter; d) a measurement at an output from the second drive unit1414of a mechanical performance parameter; e) differences in measurements at respective inputs of a first drive unit1412and a second drive unit1414of a mechanical performance parameter; f) differences in measurements at respective outputs of a first drive unit1412and a second drive unit1414of a mechanical performance parameter; g) mechanical power measurement at a powered implement1422of the maintenance apparatus100; h) a measured torque upon the maintenance apparatus100; i) time; or some combination of two or more of the latter measured parameters. These latter mechanical performance parameters may include one or more of any of the following: force, torque, energy, work, power, action, position, velocity, acceleration, jerk, angular position, angular velocity, angular acceleration, angular jerk, temperature, pressure, heat, mass, or mass flow rate.

In some aspects of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the first drive unit1412may be a first hydraulic drive motor1413. In some aspects of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the second drive unit1414may be a second hydraulic drive motor1415. In some aspects of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the first caster steering unit1432comprises a first hydraulic caster motor1434.

In some aspects of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the first function is a function with one or more measured parameters being the independent variables of the first function. In some aspects of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the first function is continuously differentiable over each of the one or more measured parameters that are the independent variables of the first function. Herein and unless otherwise noted, “continuously differentiable” has the conventional mathematical definition: a function g(x) is continuously differentiable if the derivative g′(x) exists and is itself a continuous function. It should be understood that the relevant domain of x in the latter definition is the relevant measureable range of the relevant measured parameter that is the independent variable x. In some aspects of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the first function is a linear equation, a quadratic equation, a cubic equation, or some other polynomial equation. It should be understood that it also contemplated that the first function may include other equations and terms such as those that are logarithmic, geometric, or include other exponents.

In some aspects of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the first function is a function h(p1, p2)=k(p1−p2), where k is a constant of proportionality, p1is the measurement of torque at the first drive unit1412, and p2is the measurement of torque at the second drive unit1414. It should be understood that the latter non-limiting exemplary function h determines an amount of active torque to the first caster wheel112about the first caster swivel axis118and that h is linearly proportional to the torque differential, where the torque differential is the difference in measurements of torque at the first drive unit1412and the second drive unit1414.

In another aspect of the first exemplary and non-limiting embodiment of a selective active caster steering apparatus1450, the first function is a function h(p1, p2, p3, p4) wherein p1is the measurement of torque at the first drive unit1412, p2is the measurement of torque at the second drive unit1414, P3is the measurement of angular velocity of a shaft of the first hydraulic motor1412, and P4is the measurement of angular velocity of a shaft of the second hydraulic motor. As in the prior example above, the measurement of torque at the first drive unit1412, p2is the measurement of torque at the second drive unit1414may be used to calculate the torque differential as part of the first function.

It should be understood that in the above examples the measurements of torque may be measured at either the input or the output of the respective drives as chosen with good engineering judgment. It should further be understood that constant k may be predetermined or may be an input determined simultaneously. In one non-limiting aspect constant k is determined beforehand, or calculated beforehand or simultaneously as the output of a second function.

Further to the above, and with reference to the Figures and particularly toFIGS.1,2,3,13, and14, provided is a first exemplary and non-limiting embodiment of a powered maintenance apparatus100comprising: a first drive unit1412having a first drive shaft1417, the first drive unit being adapted to produce a first mechanical output by way of the first drive shaft1417as shaft work; a second drive unit1414having a second drive shaft1418, and adapted to produce a second mechanical output by way of the second drive shaft1418as shaft work; one or more sensors130operatively engaged with the maintenance apparatus, each of the one or more sensors130being adapted measure a parameter and to output data indicative of the parameter measured; a controller1304, and a selective active caster steering apparatus operationally engaged with the powered maintenance apparatus. The controller1304may be adapted to process a first formula based on data from the one or more sensors, calculate the result of the first formula, and to send a first signal based thereon. The latter first formula is usable to determine the latter first signal indicative of an amount of active torque to be applied to the caster wheel about the caster swivel axis as a first function of one or more parameters measured by the one or more sensors. Further to the above and without limitation the first drive unit1412may be an engine, an electric motor, a hydraulic motor, or other unit chosen with good engineering judgment and capable of producing the desired first mechanical output. Similarly, the second drive unit1414may be an engine, an electric motor, a hydraulic motor, or other unit chosen with good engineering judgment and capable of producing the desired second mechanical output. The above referenced sensors130may comprise an accelerometer, a gyroscopic transducer, a timer, a clock, a strain gauge, a pressure transducer, a flow gauge, a mass flow transducer, a thermometer, a calorimeter, a voltage transducer, a magnetic field transducer, or otherwise as chosen with good engineering judgment. Similar to that noted above with respect to the selective active caster steering apparatus1450, the one or more parameters measured by the one or more sensors may comprise: a) a measurement at an input to the first drive unit1412of a mechanical performance parameter; b) a measurement at an input to the second drive unit1414of a mechanical performance parameter; c) a measurement at an output from the first drive unit1412of a mechanical performance parameter; d) a measurement at an output from the second drive unit1414of a mechanical performance parameter; e) differences in measurements at respective inputs of a first drive unit1412and a second drive unit1414of a mechanical performance parameter; f) differences in measurements at respective outputs of a first drive unit1412and a second drive unit1414of a mechanical performance parameter; g) mechanical power measurement at a powered implement1422of the maintenance apparatus100; h) a measured torque upon the maintenance apparatus100; i) time; or some combination of two or more of the latter measured parameters. Here again, these latter mechanical performance parameters may include one or more of any of the following: force, torque, energy, work, power, action, position, velocity, acceleration, jerk, angular position, angular velocity, angular acceleration, angular jerk, temperature, pressure, heat, mass, or mass flow rate. Similar to that noted above, the selective active caster steering apparatus1450may have: a caster arm defining the caster swivel axis and a caster spin axis; the caster wheel may be operationally engaged with the caster arm such that the caster wheel can be steered about the caster swivel axis; and a first caster steering unit adapted to selectably apply the amount of active torque indicated by the first signal to the caster wheel about the caster swivel axis.

In some aspects of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the first drive unit1412may be a first hydraulic drive motor1413. In some aspects of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the second drive unit1414may be a second hydraulic drive motor1415. In some aspects of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the first caster steering unit1432comprises a first hydraulic caster motor1434.

In some aspects of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the first function is a function with one or more measured parameters being the independent variables of the first function. In some aspects of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the first function is continuously differentiable over each of the one or more measured parameters that are the independent variables of the first function. As above, here, “continuously differentiable” has the conventional mathematical definition: a function g(x) is continuously differentiable if the derivative g′(x) exists and is itself a continuous function. It should be understood that the relevant domain of x in the latter definition is the relevant measureable range of the relevant measured parameter that is the independent variable x. In some aspects of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the first function is a linear equation, a quadratic equation, a cubic equation, or some other polynomial equation. Here again, it should be understood that it also contemplated that the first function may include other equations and terms such as those that are logarithmic, geometric, or include other exponents.

Similar to that above, in some aspects of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the first function is a function h(p1, p2)=k(p1−p2) where k is a constant of proportionality, p1is the measurement of torque at the first drive unit1412, and p2is the measurement of torque at the second drive unit1414. It should be understood that the latter non-limiting exemplary function h determines an amount of active torque to the first caster wheel112about the first caster swivel axis118and that h is linearly proportional to the torque differential, where the torque differential is the difference in measurements of torque at the first drive unit1412and the second drive unit1414.

Similar to that above, in another aspect of the first exemplary and non-limiting embodiment of a powered maintenance apparatus100, the first function is a function h(p1, p2, p3, p4) wherein p1is the measurement of torque at the first drive unit1412, p2is the measurement of torque at the second drive unit1414, p3is the measurement of angular velocity of a shaft of the first hydraulic motor1412, and p4is the measurement of angular velocity of a shaft of the second hydraulic motor. As in the prior example above, the measurement of torque at the first drive unit1412, p2is the measurement of torque at the second drive unit1414may be used to calculate the torque differential as part of the first function.

It should be understood that in the above examples the measurements of torque may be measured at either the input or the output of the respective drives as chosen with good engineering judgment. It should further be understood that constant k may be predetermined or may be an input determined simultaneously. In one non-limiting aspect constant k is determined beforehand, or calculated beforehand or simultaneously as the output of a second function.

Further to the above, and with reference to the Figures and particularly toFIGS.1,2,3,13, and14, provided is a first exemplary and non-limiting embodiment of a method of providing steering force in a powered maintenance apparatus100. The method comprises providing a powered maintenance apparatus100having: a first drive unit1412having a first drive shaft1417and adapted to produce a first mechanical output1416; a second drive unit1414having a second drive shaft1418, and adapted to produce a second mechanical output1419; one or more sensors130operatively engaged with the maintenance apparatus100, each of the one or more sensors130being adapted to measure a parameter and to output data indicative of the parameter measured; a controller adapted to process a first formula based on data from the one or more sensors, calculate the result of the first formula, wherein the first formula is usable to determine a first signal indicative of an amount of active torque, and send the first signal; and a selective active caster steering apparatus operationally engaged with the powered maintenance apparatus. The method further comprises measuring a parameter with each of the one or more sensors; outputting data indicative of the parameter from each of the one or more sensors to the controller; using the controller to calculate a first signal based on the parameter from each of the one or more sensors; and sending the first signal to the first caster steering unit. In the latter exemplary method, the selective active caster steering apparatus150operationally engaged with the powered maintenance apparatus, has a caster arm defining a caster swivel axis and a caster spin axis; a caster wheel operationally engaged with the caster arm such that the caster wheel can be steered about the caster swivel axis; and a first caster steering unit adapted to selectably apply the amount of active torque indicated by the first signal to the caster wheel about the caster swivel axis. It should be understood then that in the latter exemplary method, the first signal indicative of an amount of active torque is indicative of an amount of active torque to be applied to the caster wheel about the caster swivel axis. In the latter exemplary method, the first formula is usable to determine the first signal as a first function of one or more parameters measured by the one or more sensors130. The one or more parameters may include: a) a measurement at an input to the first drive unit of a mechanical performance parameter; b) a measurement at an input to the second drive unit of a mechanical performance parameter; c) a measurement at an output from the first drive unit of a mechanical performance parameter; d) a measurement at an output from the second drive unit of a mechanical performance parameter; e) differences in measurements at respective inputs of a first drive unit and a second drive unit of a mechanical performance parameter; f) differences in measurements at respective outputs of a first drive unit and a second drive unit of a mechanical performance parameter; g) mechanical power measurement at a powered implement of the maintenance apparatus; h) a measured torque upon the maintenance apparatus; i) time; or a combination thereof. In accordance with the foregoing, the method may further comprise using the first caster steering unit to output the amount of active torque indicated by the first signal to the caster wheel about the caster swivel axis to provide steering force to the powered maintenance apparatus.

In some non-limiting embodiments of the above method, the first function may be continuously differentiable over each of the one or more measured parameters.

In some non-limiting aspects of the above embodiments, the apparatus and/or method are such that the recited first drive unit1412is a first axial hydraulic motor1424comprising a first swashplate1425of the kind typical to such motors; and the recited second drive unit1414is a second axial hydraulic motor1426comprising a second swashplate1427of the kind typical to such motors. In such an embodiment, one or more sensors130may be operationally engaged with the first swashplate1425and the second swashplate1427to provide, respectively, a measurement at an output from the first drive unit1412of torque (which is a mechanical performance parameter) and a measurement at an output from the second drive unit1414of torque. These latter torque measurements, n1, n2, may be the input parameters to the first function where the first function is f(x)=k(n1−n2) and k is some constant. Alternatively, k may itself be calculated from a second function. In some aspects where k is calculated from a second function, k may be set to zero or a very small value if the second function is in a range consistent with one or both of the drive units,1412,1414or their associated drive wheels being in a slip condition, for example and without limitation, if a sensor were to detect a drive shaft angular acceleration above some threshold value. In other aspects where k is calculated from a second function, k may be set to zero or a very small value if sensors provide values of drive wheel rotation rates and vehicle motion that are different from those values projected for non-slip wheel performance by more than one or more threshold values.

With reference now toFIGS.1-13, additional details and non-limiting embodiments are set out below.

FIG.2depicts a diagram of an example lawn maintenance apparatus200according to further embodiments of the present disclosure. Lawn maintenance apparatus200illustrates a seated operator device in which an operator can drive, operate and control lawn maintenance apparatus200from a seated position. Lawn maintenance apparatus200comprises a front caster wheel(s)210and rear wheels220. Caster wheel(s)210can rotate freely about a rotation axis at a connection to a frame of lawn maintenance apparatus200. In addition, rear wheels220can be driven by one or more motors or engines secured to the frame of lawn maintenance apparatus200. Although not depicted (but seeFIGS.6-11, infra), lawn maintenance apparatus200can comprise one or more motors connected to front caster wheels in order to apply a torque on the rotation axis of the caster wheel(s)210and at least in part control direction of motion of lawn maintenance apparatus200from the front caster wheel(s)210. In an embodiment, the one or more motors can apply the torque on the rotation axis in response to a force upon a component of lawn maintenance apparatus200. To this end, a sensor230can optionally be provided to measure the force upon the component of lawn maintenance apparatus200to provide a measurement of the force to a controller (not depicted, but seeFIG.12AandFIG.12B, infra) operable to control the one or more motors.

FIG.3depicts a diagram of a lawn maintenance device300according to further embodiments of the present disclosure. Lawn maintenance device300provides another embodiment of a maintenance apparatus having a front-mount mow deck. Further, lawn maintenance device300is a seated operator apparatus enabling an operator to drive, operate and control lawn maintenance apparatus300from a seated position. Lawn maintenance apparatus300also includes a set of front caster wheels310secured to a frame supporting the front-mount mow deck. One or more drive wheels320are provided, as well as a rear wheel(s)330. Rear wheel(s)330can be a passive wheel(s) in some embodiments, or can be a steerable wheel in other embodiments. Similarly, drive wheels320can be constrained to move at the same speed (with steering controlled by rear wheel(s)330or front caster wheels310) or can operate at different speeds to effect directional control (and steering) of lawn maintenance device300.

FIG.4illustrates an example diagram of a caster wheel frame and axis400according to alternative embodiments of the present disclosure. Caster wheel frame and axis400is one illustrative mechanism by which disclosed caster wheels can be implemented and is not intended to be limiting. In the embodiment depicted byFIG.4, caster wheel frame and axis400includes a caster swivel axis418and a spin axis414. Caster swivel axis418includes a mounting rod426to secure caster wheel frame and axis400to a maintenance apparatus. Caster wheel frame and axis400can rotate about caster swivel axis418to facilitate rotation of caster wheel frame and axis400about the mounting rod426and a frame of the maintenance apparatus. A wheel mount430is provided about spin axis414to mount a wheel (not depicted) to caster wheel frame and axis400. The wheel can rotate on wheel mount430to spin about spin axis414. A distance between the spin axis414and caster swivel axis418can define a caster trail (not depicted, but seeFIG.5, infra). The caster trail facilitates a frictional force on a caster wheel about caster swivel axis418that reduces an angular displacement between a direction of motion and a rotation of caster swivel axis418, in one or more embodiments (e.g., seeFIGS.5and11, infra).

FIG.5depicts an example diagram of a caster wheel500according to further embodiments of the present disclosure. Caster wheel500comprises a wheel112secured to a caster arm116. The caster arm116secures the wheel112to a frame520of a maintenance apparatus520by way of a swivel mount526. Swivel mount526facilitates rotation of caster arm116about a caster swivel axis118, while caster arm116provides a mount for wheel112to spin about a spin axis114. A distance between caster swivel axis118and spin axis114defines a caster trail510of caster wheel500. In at least one alternative embodiment, however, a disclosed caster wheel can have zero caster trail, in which the spin axis114and caster swivel axis118are collinear or substantially collinear such that caster trail510is zero (or substantially zero).

Caster trail510can facilitate application of a rotational force on caster arm116in response to motion of wheel112. For instance, a force upon frame520(e.g., supplied by a power source and a drive wheel of a disclosed maintenance apparatus) is translated to caster arm116by way of swivel mount526and to wheel112at the mount to spin axis114. The force can in turn result in a rotational force proportional to a distance of caster trail510upon wheel112and caster arm116about caster swivel axis118. This rotational force is in a direction that minimizes angular displacement between a direction of the force upon frame520and an orientation of caster arm116about caster swivel axis118(seeFIG.11, infra). By minimizing the angular displacement, the rotational force reduces drag and promotes rotation of wheel112along a surface in response to the force upon frame520, mitigating or avoiding turfing of the surface.

FIG.6illustrates an image of an example caster wheel motor drive600according to further embodiments of the present disclosure. A caster wheel500is mechanically coupled to a selective drive motor and axis620facilitating rotation about a selective swivel/drive axis618. Selective drive motor and axis620can include a motor responsive to an electric control signal. The motor can be passive (e.g., inactivated) and provide no (driven) force upon caster wheel500about the selective swivel/drive axis618, when passive. In response to the electric control signal, the motor can activate to provide the force upon selective swivel/drive axis618to facilitate rotation of caster wheel500about the selective swivel/drive axis618. In an embodiment, the selective swivel/drive axis618of selective drive motor and axis620can have an axial friction opposing rotation of caster wheel500about selective swivel/drive axis618. The axial friction can be present even when the motor is passive (e.g., deactivated, receiving a default or minimal electric power, receiving no electric power, and so forth), in various embodiments. However, the rotation force proportional to caster trail510in response to movement of the maintenance apparatus can be effective to overcome the axial friction, in one or more embodiments. When activated, the motor of selective drive motor and axis620can have an output magnitude selected to overcome the axial friction of selective swivel/drive axis618and to orient the caster wheel500to a target direction, or to overcome the axial friction in addition to opposing a measured force upon a maintenance apparatus disclosed herein. In at least some embodiments, the drive axis of selective drive motor and axis620can be a lubricated rotational axis having negligible axial friction, and the output magnitude can be selected to orient the caster wheel500to the target direction, or the oppose the measured force without the magnitude selected to overcome the axial friction.

In some aspects of disclosed embodiments, selective drive motor and axis620can be operated in a low power mode to provide active dampening of rotation of caster wheel500about selective swivel/drive axis618. The lower power model can be selected to apply less rotational force than required to initiate rotation of caster wheel500about selective swivel/drive axis618in view of mass of caster wheel500, any rotational friction of selective swivel/drive axis618and force exerted on caster wheel500by the mass of a maintenance apparatus and frame that caster wheel500is secured to. Instead, the low power mode can be selected to apply a rotational force sufficient to mitigate rotation of caster wheel500about selective swivel/drive axis618in response to other forces (e.g., caster trail friction, gravitational force, and so on). In at least one aspect the magnitude of lower power rotational force can be adjustable by way of controls105(e.g., seeFIG.1, supra). In additional aspects, the low power mode can be implemented at a selective drive motor and axis620connected to a single caster wheel500, or to both selective drive motor and axis620connected to both caster wheels500, where suitable. In an alternative embodiment, selective drive motor and axis620or selective swivel/drive axis618can have an adjustable mechanical damper that is partly or wholly independent of power applied to selective drive motor and axis620. The mechanical damper can resist rotation of caster wheel500by mechanical friction in various implementations. Example mechanical friction can include: an adjustable friction on mechanical gears within selective swivel/drive axis618, an adjustable friction device adjacent to a rotational pin, rod, bearing, etc. of selective swivel/drive axis618that is configured to apply adjustable mechanical pressure to the rotational pin, rod, bearing, etc. to add adjustable friction thereto, or the like.

FIG.7depicts an image of a top view of an example caster wheel with motor drive700according to additional embodiments of the present disclosure. A caster wheel500is connected to a selective drive axis722and can be actively oriented about a caster swivel axis116by a selective drive motor720. In response to a signal provided over a motor control710, selective drive motor720can apply a rotational force to selective drive axis722to turn caster wheel500about caster swivel axis116. The signal can also include a direction indication for determining whether to apply the rotational force in a clockwise or counter-clockwise angular direction (looking down from a top of caster swivel axis116). In an embodiment, selective drive axis722can have an inherent axial friction opposing rotation of caster wheel500about caster swivel axis116, whereas in an alternative embodiment selective drive axis722can have negligible axial friction. The rotational force applied by selective drive axis722can be selected to overcome the axial friction, where present, in addition to turning caster wheel500about the caster swivel axis116.

FIG.8illustrates an image of an example caster wheel with motor drive800illustrating additional aspects of disclosed embodiments. Caster wheel with motor drive800depicts the caster wheel from an interior of a frame of a maintenance apparatus to which caster wheel with motor drive800is secured. A selective drive motor720is mounted to the frame having a mechanical torque output located at a selective drive axis722of the caster wheel with motor drive800. The caster wheel is secured to the selective drive axis722, causing the torque output provided to the selective drive axis722to apply a rotational force to the caster wheel. A motor control710is connected to selective drive motor720to cause the selective drive motor720to generate the torque output, and in one or more embodiments, to specify a direction and magnitude of the torque output.

FIG.9depicts a diagram of an example front suspension900of a maintenance apparatus, in additional aspects of the disclosed embodiments. The maintenance apparatus can be a lawn maintenance device, such as a lawn mower, a riding lawn mowing device, a walk-behind lawn mowing device, a remote-controlled lawn mowing device, a partially or fully autonomous and automated lawn mowing device, or the like, or a suitable combination thereof. Front suspension900can comprise a first suspension arm940and a second suspension arm942(referred to collectively as suspension arms940,942). A selective drive motor720is attached to one side of the second suspension arm942, and a like selective drive motor is attached to first suspension arm940. The selective drive motors720can be configured to output a torque(s) upon respective selective drive axis722of suspension arms940,942to effect rotation of caster wheels connected to suspension arms940,942. In various embodiments, a torque applied to the selective drive axis722of first suspension arm940by a first selective drive motor720can be selected to be the same or different magnitude (or direction) from a second torque applied to selective drive axis722of second suspension arm942by a second selective drive motor720.

A direction and magnitude of the torque(s) upon the respective selective drive axis722can be determined in response to a measurement of torque or force upon the maintenance apparatus. The measurement of torque can be acquired at a PTO clutch or PTO anti-rotation pin of the maintenance apparatus, in an embodiment. The measurement of torque can be a difference in instantaneous torque output by different motors driving respective drive wheels of the maintenance apparatus, in another embodiment. The measurement of force can be a difference in instantaneous power consumption of different motors driving respective drive wheels of the maintenance apparatus, in yet another embodiment. The measurement of torque or force can be a torque or force upon a caster wheel(s) at selective drive axis722by an optional sensor in drive axis930, in yet additional embodiments. In still other embodiments, another measurement of force known in the art or reasonably conveyed to one of ordinary skill in the art by way of the context provided herein, or any suitable combination of the foregoing can be provided.

FIG.9Aillustrates an embodiment of a maintenance apparatus900A with an example front suspension according to additional aspects of the present disclosure. Maintenance apparatus900A comprises a (single) selective drive motor920A secured to a front portion of maintenance apparatus900A. A shared front wheel axis arm926A provides steering control to a left front wheel912A and right front wheel914A in response to drive output from selective drive motor920A, by way of a motor-arm coupling922A. Shared front wheel axis arm926A is mechanically coupled to caster swivel axis918A of left front wheel912A and right front wheel914A by way of arm-swivel axis coupling932A. Accordingly, in response to activation of selective drive motor920A shared front wheel axis arm926A is manipulated to rotate left front wheel912A and right front wheel914A about respective caster swivel axis918A, to effect turning of front wheels912A and914A. Moreover, selective drive motor920A can be responsive to a steering mechanism, such as controls105ofFIG.1, supra. In other aspects, the steering mechanism can be a remote control steering, a drive-by-wire steering control, or an automated (or partially automated) steering control module of an automated steering control device (which can be implemented at least in part utilizing a computer1102ofFIG.11, infra, or like computer-implemented steering module).

FIG.9Billustrates a further embodiment of an example front wheel pivot frame900B for a maintenance apparatus according to additional embodiments of the present disclosure. Front wheel pivot frame900B includes pivot frame910B or pivot bar that provides a stable mechanical link between caster swivel axis918A connected to left front wheel912B and right front wheel914B. Pivot frame910B can be secured to the maintenance apparatus at least by a pivot joint920B (though one or more other joints may secure pivot frame910B to the maintenance apparatus in various embodiments). Pivot joint920B permits rotation of pivot frame910B relative to the maintenance apparatus about a rotation axis of pivot joint920B. This allows left front wheel912B and right front wheel914B a degree of movement depicted by wheel lift/drop922B (for left front wheel912B) and wheel lift/drop924B (for right front wheel924B) in opposing relative directions. For example, as pivot frame910B rotates counter-clockwise about pivot joint920B—as depicted—right front wheel914B lifts upward and left front wheel912B drops downward. For clockwise rotation about pivot joint920B, the reverse is true: right front wheel914B drops downward and left front wheel912B lifts upward. The relative up-down movement resulting from rotation of pivot frame910B about pivot joint920B can allow left front wheel912B and right front wheel914B some independence in tracking a surface upon which the maintenance apparatus is moving and maintaining ground contact (or increasing time of ground contact and decreasing time of non-contact) of left front wheel912B and right front wheel914B over uneven terrain. In various embodiments, pivot joint920B can facilitate rotation of a few degrees to several degrees clockwise and counterclockwise about an axis of pivot joint920B. In some embodiments, one or more bumpers (not depicted) can be mounted to a frame of the maintenance apparatus above or below respective ends of pivot frame910B to (physically) halt rotation of pivot frame910B further than the few to several degrees of clockwise or counterclockwise motion about pivot joint920B. In an embodiment, the few to several degrees of clockwise and counter-clockwise rotation can be zero to five degrees, zero to seven degrees, zero to ten degrees, or the like, or any suitable value or range there between.

FIG.10depicts an example caster wheel with selective drive motor1000according to still further aspects of embodiments disclosed herein.FIG.10illustrates a portion of a suspension arm942of a maintenance apparatus from an overhead perspective, including caster wheel and selective drive motor1000and a selective drive motor720secured to the suspension arm942. Selective drive motor720outputs a torque at a selective drive axis722in response to a signal from a motor control710. Additionally, a caster wheel1030is mounted to the selective drive axis722and is configured to rotate about an axis of rotation of selective drive axis722. In an aspect of the disclosed embodiment(s), caster wheel1030can rotate together with rotation of selective drive axis722itself. In another aspect, caster wheel1030rotates in part at a different rate from that of selective drive axis722, or rotates about selective drive axis722, which remains stationary. Also depicted is a selective drive axis rotational mechanism1022facilitating rotation of the caster wheel1030, and optionally facilitating rotation of selective drive axis722as well. Selective drive axis rotation mechanism1022can be a lubricated pin, bearing, or other suitable mechanical mechanism facilitating rotation about an axis having negligible friction, in an embodiment. In other embodiments, selective drive axis rotation mechanism1022can be an electromechanical device facilitating the driving of rotation of caster wheel1030about selective drive axis722, when selective drive motor720is activated, as well as allowing rotation of caster wheel1030about selective drive axis722in response to friction, gravity or other movement-related forces about selective drive axis722when selective drive motor720is deactivated. In some aspects of disclosed embodiments, selective drive axis722can have an axial friction that is non-negligible providing some resistance to rotation about selective drive axis722when selective drive motor720is deactivated.

FIG.11depicts an example diagram of a rotational force1100upon a caster wheel1030according to various disclosed embodiments. The rotational force1100illustrated inFIG.11pertains to a force in response to movement of caster wheel1030in response to a force applied by suspension arm940upon caster wheel1030, such as when a maintenance apparatus including suspension arm940is driven by a drive wheel(s), or other motive force. Additionally, the non-powered caster wheel rotational force1100ignores any force from selective drive motor720, and thus can be operable when selective drive motor720is deactivated. When activated, selective drive motor720can provide an applied rotation force (not depicted) on a selective swivel/drive axis618mechanically coupled to caster wheel1030in addition to the rotational force1100, or subtracting from the rotational force1100depending upon relative direction of the applied rotation force and rotational force1100.

The example illustrated byFIG.11shows caster wheel1030having a wheel orientation1124as compared with a forward direction1122of a maintenance apparatus. Forward direction1122is defined by (and in a direction of) a force applied by suspension arm940on selective swivel/drive axis618and caster wheel1030and can also be referred to as a zero angle with respect to wheel orientation1124of caster wheel1030. The force applied by suspension arm940causes motion and turning of caster wheel1030on a surface, which in turn results in a friction force1130having a component in a direction opposite the forward direction1122. The friction force1130causes a rotation force1132in response to the friction force1130, that is proportional to a length of a caster trail410of caster wheel1030and related to angular displacement1126. This rotation force1132is in a direction that minimizes angular displacement1126. With angular displacement1126as shown inFIG.11, rotation force1132is in a counter-clockwise direction (looking at the page ofFIG.11). If instead angular displacement1126is above the line illustrated by forward direction1122, rotation force1132will be in a clockwise direction (also minimizing angular displacement1126).

Note thatFIG.11does not illustrate an effect of axial friction of selective swivel/drive axis618on rotation force1132. Where selective swivel/drive axis618is a suitably lubricated pin, bearing or other rotational coupling, the effect of the axial friction can be negligible and ignored. In other embodiments, for instance where selective swivel/drive axis618is a mechanical or electro-mechanical powered axis, a significant axial friction can affect rotational forces at selective swivel/drive axis618, including rotation force1132responding to friction1130, an applied force provided by selective drive motor720upon selective swivel/drive axis618, a gravitational force on caster wheel1030and suspension arm940, an inertial force(s) on suspension arm940and caster wheel1030, and so forth. In one or more embodiments, the applied force provided by selective drive motor720can be configured to counteract, or to overcome, where suitable, rotation force1132on selective swivel/drive axis618in addition to other forces acting upon selective swivel/drive axis618, such as the axial friction, gravitational force, and so forth. In other embodiments, selective drive motor720can be configured to apply a force proportional to a sensor measurement (e.g., an optional sensor930in selective swivel/drive axis618, a sensor at a PTO clutch or PTO anti-rotation pin, a relative torque output at hydraulic motors of a maintenance apparatus, a relative power consumption at electric motors of a maintenance apparatus, and so forth) that is in part or in whole independent of rotation force1132and other forces upon selective swivel/drive axis618, where suitable.

FIGS.12A and12Billustrate embodiments of a caster wheel orientation sensor1200depicted in a side-view orientation inFIG.12Aand an overhead view orientation inFIG.12B. Caster wheel orientation sensor1200is embodied, by the example illustrated inFIGS.12A and12B, with a swivel axis orientation sensor1210and a sensor mount1215. It should be appreciated, however, that different shape, style, size and manner of mount1215can be utilized as suitable to secure swivel axis orientation sensor1210to selective swivel/drive axis618in a suitable position to achieve the function of detecting, measuring or monitoring rotational orientation of a caster arm116and caster wheel500of a disclosed maintenance apparatus. In the example illustrated byFIGS.12A and12B, caster wheel500and caster arm116can rotate within selective swivel/drive axis618by way of a swivel device (e.g., mounting rod426ofFIG.4, supra). Swivel axis orientation sensor can be configured to measure a rotational orientation of the swivel device in order to determine a rotational orientation of caster wheel500. As one example, a hall effect sensor included within swivel axis orientation sensor1210can measure rotational position of a fixed magnet mounted to a top surface of the swivel device (e.g., mounting rod426) to determine a rotational orientation of the swivel device. Sensor wiring1210can be provided to power swivel axis orientation sensor1210, and to transfer data from swivel axis orientation sensor1210to a controller, described herein. Data specifying the rotational orientation of the swivel device can be transferred to the controller which can infer a rotational orientation of the caster wheel500there from. Accordingly, swivel axis orientation sensor1210can facilitate determination of current rotational orientation of caster wheel500and enable turning instructions to be generated to turn caster arm116by selective drive motor720to accomplish turning caster arm116from the current rotational orientation to a subsequent rotational orientation. This can facilitate steering a disclosed apparatus by way of caster arm116and caster wheel500, in at least some disclosed embodiments, countering effects of torque or force upon the apparatus that affect orientation of caster arm116and caster wheel500in still other embodiments, or a combination of the foregoing in still further embodiments.

With reference now to the nonlimiting embodiment shown inFIG.13, a disclosed controller can be embodied within hardware, such as a single integrated circuit (IC) chip, multiple ICs, an application specific integrated circuit (ASIC), or the like. A suitable operating environment1300for implementing various aspects of the claimed subject matter includes a computer1302. Computer1302can embody a motor drive controller, in some embodiments, and can include only a subset of components identified herein as part of computer1302in some embodiments, whereas in other embodiments other components known to one of ordinary skill that are not depicted can nonetheless be included in computer1302. In alternative or additional embodiments, a control unit of a maintenance apparatus (which can be separate from the above motor drive controller, or combined with such controller) can be embodied in part by computer1302, or an analogous computing device known in the art, subsequently developed, or made known to one of ordinary skill in the art by way of the context provided herein.

The computer1302includes a processing unit1304, a system memory1310, a codec1314, and a system bus1308. The system bus1308couples system components including, but not limited to, the system memory1310to the processing unit1304. The processing unit1304can be any of various available processors. Dual microprocessors and other multiprocessor architectures also can be employed as the processing unit1304.

The system memory1310can include volatile memory1310A, non-volatile memory1310B, or both. Functions of a motor drive controller or apparatus control unit described in the present specification can be programmed to system memory1310, in various embodiments. The basic input/output system (BIOS), containing the basic routines to transfer information between elements within the computer1302, such as during start-up, is stored in non-volatile memory1310B. In addition, according to present innovations, codec1314may include at least one of an encoder or decoder, wherein the at least one of an encoder or decoder may consist of hardware, software, or a combination of hardware and software. Although, codec1314is depicted as a separate component, codec1314may be contained within non-volatile memory1310B. By way of illustration, and not limitation, non-volatile memory1310B can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or Flash memory. Non-volatile memory1310B can be embedded memory (e.g., physically integrated with computer1302or a mainboard thereof), or removable memory. Examples of suitable removable memory can include a secure digital (SD) card, a compact Flash (CF) card, a universal serial bus (USB) memory stick, or the like. Volatile memory1310A includes random access memory (RAM), which can act as external cache memory, and can also employ one or more memory architectures known in the art, in various embodiments. By way of illustration and not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), and enhanced SDRAM (ESDRAM), and so forth.

Computer1302may also include removable/non-removable, volatile/non-volatile computer storage medium.FIG.13illustrates, for example, disk storage1306. Disk storage1306includes, but is not limited to, devices such as a magnetic disk drive, solid state disk (SSD) floppy disk drive, tape drive, Flash memory card, memory stick, or the like. In addition, disk storage1306can include storage medium separately or in combination with other storage medium including, but not limited to, an optical disk drive such as a compact disk ROM device (CD-ROM) or derivative technology (e.g., CD-R Drive, CD-RW Drive, DVD-ROM, and so forth). To facilitate connection of the disk storage1306to the system bus1308, a removable or non-removable interface is typically used, such as interface1312. In one or more embodiments, disk storage1306can be limited to solid state non-volatile storage memory, providing motion and vibration resistance for a motor controller, control unit or the like operable in conjunction with a power equipment machine (e.g., maintenance apparatus100).

It is to be appreciated thatFIG.13describes software that can program computer1302to operate as an intermediary between an operator of a maintenance apparatus (e.g., maintenance apparatus100,200,300, etc.) or a component thereof (e.g., selective drive motor720), operate as an intermediary between the maintenance apparatus or component and an autonomous control system for operating the maintenance apparatus/component embodied within operating environment1300, in at least some embodiments. Such software can include an operating system1306A. Operating system1306A, which can be stored on disk storage1306, acts to control and allocate resources of the computer1302. Applications1306C take advantage of the management of resources by operating system1306A through program modules1306D, and program data1306B, such as a boot/shutdown transaction table and the like, stored either in system memory1310or on disk storage1306. It is to be appreciated that the claimed subject matter can be implemented with various operating systems or combinations of operating systems.

Input device(s)1342connects to the processing unit1304and facilitates operator interaction with operating environment1300through the system bus1308via interface port(s)1330. Input port(s)1340can include, for example, a serial port, a parallel port, a game port, a universal serial bus (USB), among others. Output device(s)1332can use some of the same type of ports as input device(s)1342. Thus, for example, a USB port may be used to provide input to computer1302and to output information from computer1302to an output device1332. Output adapter1330is provided to illustrate that there are some output devices, such as graphic display, speakers, and printers, among other output devices, which require special adapters. The output adapter1330can include, by way of illustration and not limitation, video and sound cards that provide a means of connection between the output device1332and the system bus1308. It should be noted that other devices or systems of devices provide both input and output capabilities such as remote computer(s)1324and memory storage1326.

Computer1302can operate in conjunction with one or more electronic devices described herein. For instance, computer1302can embody a control unit configured to receive and process data from optional sensor130and output a selected rotation force and direction to selective drive motor720. Additionally, computer1302can be configured to select a force at selective drive motor720that counters a force measured at optional sensor130(or measured at another sensor, such as a differential torque output sensor, a differential power consumption sensor, and so forth), or select a force to drive caster arm116and wheel112to a target direction or angle in response to a steering input of an operator, remote control or (semi-) autonomous control unit, as described in embodiments throughout the disclosure. Computer1202can couple with optional sensor130(or other sensor(s)) or selective drive motor720by way of a network interface1322(e.g., wired or wireless) in an embodiment.

Communication connection(s)1320refers to the hardware/software employed to connect the network interface1322to the system bus1308. While communication connection1320is shown for illustrative clarity inside computer1302, it can also be external to computer1302. The hardware/software necessary for connection to the network interface1322includes, for exemplary purposes only, internal and external technologies such as, modems including regular telephone grade modems, cable modems and DSL modems, ISDN adapters, and wired and wireless Ethernet cards, hubs, and routers.

It should be further understood that a part-time automatic active caster drive could be established by adding a take-off line at each of the first hydraulic drive motor1413and the second hydraulic drive motor1415to produce an output hydraulic from the drive motors to a hydraulic motor on the caster and thereby turn casters in a proportional response to the torque differential at the drive motors.

In regard to the various functions performed by the above described components, machines, apparatuses, devices, processes, control operations and the like, the terms (including a reference to a “means”) used to describe such components, etc., are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., a functional equivalent), even though not structurally equivalent to the disclosed structure, which performs the function in the herein illustrated exemplary aspects of the embodiments. In this regard, it will also be recognized that the embodiments include a system as well as mechanical structures, mechanical drives, electronic or electro-mechanical drive controllers, and electronic hardware configured to implement the functions, or a computer-readable medium having computer-executable instructions for performing the acts or events of the various processes or control operations described herein.

In other embodiments, combinations or sub-combinations of the above disclosed embodiments can be advantageously made. Moreover, embodiments described in a particular drawing or group of drawings should not be construed as being limited to those illustrations. Rather, any suitable combination or subset of elements from one drawing(s) can be applied to other embodiments in other drawings where suitable to one of ordinary skill in the art to accomplish objectives disclosed herein, objectives known in the art, or objectives and operation reasonably conveyed to one of ordinary skill in the art by way of the context provided in this specification. Where utilized, block diagrams of the disclosed embodiments or flow charts are grouped for ease of understanding. However, it should be understood that combinations of blocks, additions of new blocks, re-arrangement of blocks, and the like are contemplated in alternative embodiments of the present disclosure.