Crop feeler system and method

In some embodiments, a crop feeler system automatically executes a navigational task based on a proximity of a vehicle to an obstacle. The crop feeler system includes a hub attached to the vehicle. Inside the hub are two oscillating circuits each having an oscillating frequency. A member is coupled to the hub. Two inductive elements are positioned within the member so that, when the obstacle comes into contact with the member, at least one of the inductive elements moves closer to at least one of the oscillating circuits and alters the oscillating frequency of that oscillating circuit. A navigation sensor measures the oscillating frequency of the oscillating circuit, identifies a navigational task using the oscillating frequency of the oscillating circuit, and executes the navigational task.

TECHNICAL FIELD

Embodiments of the present invention relate generally to systems and methods for navigating a vehicle, and in particular, to detecting the proximity of the vehicle with respect to an object and automatically steering the vehicle based on the proximity of the vehicle with respect to the object.

BACKGROUND

Various vehicles are used during the farming process. For example, some farmers use tractors or combines to plant, spray, or harvest crops in a field. In many cases, farmers wish to avoid driving farming vehicles or farming instruments into crops or colliding with other obstacles or with the ground.

SUMMARY

Some embodiments of the present invention utilize a set of inductive elements, such as soft ferrite cores, placed within or on a flexible member, such as a wand. The flexible member is coupled to a hub on a vehicle. Inside the hub are two oscillating circuits that each include an inductor coil, which may be wrapped around a soft ferrite U-core. As the vehicle approaches a crop, the flexible member will contact the crop and flex towards the housing, bringing an inductive element in the flexible member closer to an oscillating circuit. This increases the overall inductance of the oscillating circuit and thereby changes the oscillating frequency of that oscillating circuit. A navigation sensor measures the oscillating frequency of each oscillating circuit, determines a navigational task based on the oscillating frequencies, and executes the navigational task.

DETAILED DESCRIPTION

In the embodiments shown inFIG. 1, a crop feeler system100includes a hub102and a member104. The hub102is attached to a vehicle (e.g., to the front end of the vehicle or to a boom attached to the vehicle). On or inside the hub102are oscillating circuits112,114, which include inductors116,118, respectively. The hub102also includes a navigation sensor119that includes a frequency analyzer120coupled to the oscillating circuits112,114. As shown inFIG. 1, a single member104is attached to the hub102at approximately a midpoint110of the member104. The member104may be a flexible member, such as a flexible wand, that tapers down towards its outer edges. The member104includes inductor elements130,132that are located on opposite sides134,136of the member104. As the vehicle encounters an object, for example, a crop133,135, the sides134,136of the member104will flex towards the hub102, bringing the inductor elements130,132closer to the oscillating circuits112,114and to the inductors116,118. This will increase inductance of the oscillating circuits112,114and thereby change the oscillating frequency of the oscillating circuits112,114. The navigation sensor119measures the changed frequency of the oscillating circuits112,114and uses those frequencies to determine the proximity of the vehicle to crop133,135and/or to determine navigational instructions to automatically steer the vehicle with respect to the crop133,135. The details of that system and process, as well as particulars regarding the hub100and the member102, according to various embodiments, are discussed below in more detail.

The hub102shown inFIG. 1has a curved front surface137and a back surface138. In some embodiments, the front surface137forms an angle139with the back surface138that ranges from 15° to 20°, though embodiments with larger and smaller angles139are also contemplated. The back surface138may be flat or otherwise shaped to facilitate coupling to the vehicle. Various shapes and configurations are also envisioned for the hub102. For example, hub102could be a hemisphere, a cylinder, a modified pyramid, a modified cone, or any section of any one of those geometric configurations. In some embodiments, the curved surface137is used to prevent additional stress points where the member104contacts the hub102. The hub102may be formed by injection molding.

The hub102includes oscillating circuits112,114located within the hub102, partially within the hub102, or external to the hub102(e.g., on or flush with the front surface137). In the embodiments shown inFIG. 1, the oscillating circuits112,114are placed in opposing regions of the hub102. For example, oscillating circuit112may be placed on a left side of the hub102and the oscillating circuit114may be placed on a right side of the hub102. In other embodiments, the oscillating circuits112,114may both be placed on the same side of the hub102. The hub102may include one, two, three, or more oscillating circuits. In some embodiments, the oscillating circuits112,114are placed so that there is approximately one-half inch of space between each oscillating circuit112,114and its corresponding inductor element130,132when no object or external force is pushing or pulling on the member102. In those embodiments, the one-half inch of space may vary by one-quarter of an inch or more.

The oscillating circuits112,114may take a variety of forms, such as, for example, Vacká{hacek over (r)} oscillators, Colpitts oscillators, Hartley oscillators, or any other stable oscillator known in the art. The oscillating circuits may be either series tuned circuits or parallel tuned circuits. In addition, the oscillating circuits may be formed with integrated circuits or with discrete circuit components.

In some embodiments, the oscillating circuits112,114oscillate at an oscillating frequency or at a range of oscillating frequencies. The frequency or range of frequencies at which the oscillating circuits oscillate may depend on, e.g., specific electronic components within the oscillating circuits (such as particular capacitors, inductors, etc.) as well as various components external to the oscillating circuits (such as connecting cables, nearby circuits, etc.) or other electro-magnetic influences contributed by various features of the hub, wand, vehicle, etc. In some embodiments, each oscillating circuit112,114may be insulated from other components of the crop feeler system100to reduce or eliminate electro-magnetic sources affecting the oscillating frequencies of the oscillating circuits112,114. For example, components of an oscillating circuit may be electrically insulated from other components by insulating materials, such as urethane-based materials. In addition, the oscillating circuits112,114may be located away from each other to minimize electro-magnetic interactions between the oscillating circuits112,114.

In the embodiments shown inFIG. 1, the oscillating circuits112,114each include an inductor116,118. In other embodiments, the oscillating circuits112,114do not include inductors116,118, but instead include other components that are responsive to changes in electro-magnetic characteristics of the system100. Within the hub102, as shown inFIG. 1, the inductor116is wrapped around a soft ferrite U-core140and the inductor118is wrapped around another soft ferrite U-core142. Those soft ferrite U-cores140,142may be formed of a manganese-zinc-based ferrite. In other embodiments, the inductors116,118may be wrapped around cores of varying compositions and varying geometric configurations. For example, the cores may be formed of a material (e.g., a ferrite material) with a high initial permeability. The materials for the cores may also be selected based on their response to various temperatures. The cores may also be rods or I-cores instead of U-cores. In some embodiments, the inductors116,118are each wrapped around cores of different compositions or are not wrapped around a core.

As also shown inFIG. 1, the member104includes an inductor element130, such as a manganese-zinc-based ferrite I-core. Because the member104is designed to contact obstacles, using ferrite cores is particularly useful because those cores will still operate with a relatively high degree of proficiency even after enduring repeated blows and/or physical cracking or breaking. In other embodiments, the inductor element130may be ferromagnetic cores of varying compositions and geometric configurations, similar to the cores140,142discussed above.

In the embodiments illustrated byFIG. 1, the member104includes inductor elements130,132placed in opposite sides of the member104. For example, inductor element130may be placed on the left half134of the member104and inductor element132may be placed on the right half136of the member104. In other embodiments, both the inductor element130and the inductor element132may be placed on the same side or portion of the member104. Additional inductor elements may be placed on either side of the member104. The inductor elements may be placed within the member104, on an outer surface of the member104, or within a recess so that an outer surface of an inductor element lies flush with the outer surface of the member104. According to some embodiments, the location and position of the inductor elements correspond to the locations of oscillating circuits in the hub102, such that each inductor element is associated with a single oscillating circuit, and vice versa. In other embodiments, more than one inductor element is associated with a single oscillating circuit and/or more than one oscillating circuit is associated with a single inductor element.

When the crop feeler system100encounters an obstacle133, such as a crop, the member104will contact the obstacle133, which causes the member to flex toward the hub102. For example, if the left side134of the member104contacts the obstacle133, it will flex towards the hub102along an arc150that intersects the oscillating circuit112. In this manner, the inductive element130is brought closer to the oscillating circuit112. Bringing the inductive element130closer to the oscillating circuit112will alter the frequency at which the oscillating circuit112oscillates. Likewise, if the right side136of the member104contacts an obstacle135, it will flex towards the hub along an arc152that intersects the oscillating circuit114, thus altering the frequency at which the oscillating circuit114oscillates. In those embodiments, the inductive elements130,132will increase the overall system inductance affecting the oscillating circuits112,114, causing the oscillating frequencies of those oscillating circuits112,114to decrease. In some embodiments, the member104is designed to contact a particular type of obstacle, e.g., corn stalks. In those embodiments, the member104is formed with a particular resiliency for that obstacle. Other members104with varying characteristics may be used to contact different types of obstacles (e.g., a more flexible member104would be used with soybean plants than with corn stalks).

In some embodiments, the hub102includes a navigation sensor119, which may include one or more processor-based components. In some embodiments, the navigation sensor119includes one or more frequency analyzers120, one or more directional adjusters160adapted to identify steering directions for the vehicle (e.g., actions needed to move the vehicle away from the object contacting the member104) based on the frequency of the oscillating circuit, and memory162that includes a set of calibration data used by the directional adjusters160. In some embodiments, the memory162stores a set of calibration data that may be generic calibration data or calibration data derived using the particular crop feeler system100in which the calibration data is stored. Components of the navigation sensor119may be included within the hub102or may be located outside of the hub102(e.g., incorporated into an external computer or server).

The navigation sensor119determines, executes, and/or transmits a navigational task based on the proximity of the vehicle to the obstacle. An exemplary navigational task is determining navigation directions for steering the vehicle and/or implementing those navigation directions. Another navigational task is determining the distance from the vehicle to the obstacle and displaying that distance to the vehicle's user. Other navigational tasks include calculating the distance from the vehicle to the obstacle, storing the distance in a database, wirelessly transmitting the distance to a remote server, and/or mapping crop locations. In some embodiments, the navigation sensor119measures the frequency of the oscillating circuits112,114and uses that data to determine specific navigational actions without specifically computing the distance from the vehicle to the obstacle.

In some embodiments, the navigation sensor119records a series of frequency measurements for one or more oscillating circuits based on a series of member displacements and uses that set of data to determine the general relationship between the vehicle and the obstacles (e.g., the crop). The navigation sensor119may then compute navigational directions. Thus, in these embodiments, individual measurements are not used in isolation but are instead used as part of an ensemble of measurements. For example, in some embodiments, the navigation sensor119determines member displacement (e.g., the distances one or more members or ends of members104have moved due to contact with an obstacle) by applying a series of frequency measurements to a displacement curve generated with calibration data. In other words, the navigation sensor119translates the series of frequency measurements into displacement indications using the displacement curve. In a specific example, the obstacles may be a pair of crop rows, with small distance discrepancies between individual plants in the row (e.g., because each plant grows slightly differently, because some plants may be planted slightly off-center, or because of a small gap in a crop row). Using an ensemble technique allows the navigation sensor119to determine the navigational action with respect to the general trajectory of the crop rows (e.g., aligning the vehicle with a midpoint between two rows), rather than requiring individual responses from contact with each plant in each row.

In some embodiments, the navigation sensor119may average frequency measurements for a particular oscillator as part of an ensemble technique. The navigation sensor119may also assign weight values to certain frequency measurements as part of an ensemble technique. For example, if a crop row has a small gap, the frequency measurements for the oscillating circuit assigned to that crop row will indicate that the member104was in the unflexed position while in that gap and in a flexed position otherwise. In that scenario, the navigation sensor119may be programmed to remove, ignore, or assign weight values to particular data points (e.g., outlying data points) to more accurately determine the navigation task with respect to the crop row as a whole. The navigation sensor may assign weight values either to frequency measurements before applying those frequency measurements to a displacement curve or to the displacement determinations after the frequency measurements have been applied to the displacement curve. For another example, the navigation sensor119may use only the maximum member displacement or minimum member displacement over a period of time to determine the navigational action. In some embodiments, the navigation sensor119may be coupled to two hubs assigned to the same crop rows. In those embodiments, the navigation sensor119may average the measurements from each hub. The particular method for determining the navigational action (e.g., selecting an ensemble technique) may be task specific.

The output of the navigation sensor (e.g., the directional adjuster160) may be transmitted to other system components using either wired or wireless protocols and/or may be transmitted for user consumption through other mechanisms (e.g., through audio signals). In some embodiments, the output of the directional adjusters160is conveyed to a vehicle control system164, which automatically steers the vehicle based on that output. In some embodiments, the frequency analyzer120, the directional adjusters160, and/or the vehicle control system164share a single processor, while in other embodiments those components each employ a dedicated processor. In some embodiment the vehicle control system164includes components within the hub102while in other embodiments the vehicle control system164is external to the hub102. WhileFIG. 1depicts components as located inside the hub102, in other embodiments some or all of those components are located outside the hub102. For example, if multiple hubs are located on a vehicle, the crop feeler system may employ a single navigation sensor119centrally located outside of the hubs and/or may employ a single directional adjuster160centrally located outside of the hubs with frequency analyzers120placed within each hub.

In some embodiments, the vehicle includes multiple hubs102placed on both sides of the vehicle. For example, two or more hubs102may be placed on either side of a tractor boom. The location of one or more hubs102on the each side of a boom may correspond to a separation between rows of crops. In some embodiments, the hubs102are fixed to the vehicle at predetermined distances, while in other embodiments the hubs102are selectively fixed to the vehicle and can slide along the vehicle (e.g., along the boom) to a determined position. In some embodiments, the hubs102are placed so that the center of each hub102aligns with a midline between two rows of crops. As the vehicle progresses down the field, if the vehicle veers off its intended course (e.g., slightly to the left), the left side134of the member104will contact the left crop row. The navigation sensor119detects the deviation through the changed oscillating frequencies and automatically adjusts the course of the vehicle. In other embodiments, the navigation sensor119computes how far the vehicle has deviated from a preset course based on measurements from one or more hubs and conveys that information to a user. In some embodiments, each end134,136of the member104contacts a crop row, and the navigation sensor119compares the oscillating frequencies to determine whether the vehicle has deviated from its intended course.

In some embodiments, the navigation sensor119includes an override feature that allows a user to reset or re-zero the navigation sensor119. Specifically, the determinations made by the navigation sensor119may drift over time, for example, because of temperature changes that affect the oscillating frequencies. The override feature allows a user to navigate the vehicle to the midline between two crop rows and instruct the navigation sensor119to treat the current set of oscillating frequencies as indicative of the correct position with respect to the crop rows.

FIG. 2depicts embodiments in which inductor elements230,232are placed within separate members204,205. While the embodiments inFIG. 2illustrate the inductor elements230,232placed towards a distal end270,272of the members204,205, in other embodiments the inductor elements230,232may be placed toward a proximal end274,276of the members204,205. In some embodiments, the members204,205are flexible members that are rigidly fixed at the proximal end274,276to the hub202. For example, the members204,205, like the member104inFIG. 1, may be fixed to the hub202by clamps or by a set of bolts. In other embodiments, the members204,205are rigid members that are flexibly coupled to the hub202at the proximal end274,276. For example, the members204,205may each be coupled to the hub202using springs or a resilient adhesive. In yet other embodiments the members204,205may be either flexible or rigid and may be flexibly or rigidly fixed to the hub202. Like the embodiments discussed above, the members204,205move their inductive elements230,232toward oscillating circuits212,214in the hub202along arcs or curves250,252after contacting obstacles233,235. Thereafter, the navigation sensor219measures the oscillating frequencies altered by the moving inductive elements to identify and execute navigational tasks. The navigation sensor219may employ a frequency analyzer220, directional adjuster260, and/or memory262that stores calibration data for the system200, as well as a vehicle control system264.

The embodiments shown inFIG. 2also include inductors216and218that are wrapped around soft ferrite U-cores240and242, respectively.FIG. 2also shows that the inductor element230is located within the left half234of the member204, that the inductor element232is located within the right half236of the member205, and that the hub202includes a curved front surface238and a back surface239.

In the embodiments shown inFIG. 3, the crop feeler system300includes a member303that extends vertically from the hub302. Like the member204and/or205inFIG. 2, member303includes an inductive element331. The hub302includes an oscillating circuit313with an inductor317wrapped around a soft ferrite U-core341. In some embodiments, the member303is vertically aligned to control the height of the vehicle or the height of a component of the vehicle. For example, if the vehicle employs a sugar cane cutter or a plow, the user may be concerned about the height of the cutter or the plow relative to the crop or to the ground. For another example, the user may be concerned that a bottom portion of the vehicle or the hub may contact the ground. As the member303contacts an object (e.g., object333) or the ground385, the member303will flex towards the hub302and bring the inductive element331closer to the oscillating circuit313. This will alter the oscillating frequency of the oscillating circuit313. The navigation sensor319, which includes a frequency analyzer320, a directional adjuster360and/or a memory362, and which may be coupled to a vehicle control system364, measures the oscillating frequency and, in combination with the vehicle control system364, automatically adjusts the height of the vehicle (e.g., the cutter) to a desired level and/or executes other navigational tasks. WhileFIG. 3illustrates a single member303, it is contemplated that multiple downwardly-extending members303could be used and/or horizontal members (e.g., member104inFIG. 1) could be used in conjunction with one or more downwardly-extending members303.

In some embodiments, the response for each crop feeler system is generally consistent. However, in some embodiments the crop feeler system exhibits some non-linear properties. Thus, while in some embodiments a single set of calibration data could be used for multiple crop feeler systems, in other embodiments accurate results may be obtained if each crop feeler system has its own set of calibration data. Once created, the calibration data may be stored in the memory of the navigation sensor.

FIG. 4illustrates various steps that may be performed by the crop feeler system (e.g., crop feeler system100) according to some embodiments in order to create a particular set of calibration data for the crop feeler system. The crop feeler system may also perform additional steps not explicitly shown inFIG. 4or may perform less than all the steps shown inFIG. 4. As shown in step402, the oscillating frequency of an oscillating circuit is measured when the member is in an unflexed position (i.e., a default position when no external forces propel the member towards the hub). As shown in step404, data indicative of the oscillating frequency is stored in a calibration table (e.g., in memory162). As shown in step406, one side of the member (e.g., side134with inductive element130) is flexed to a specific flexing position (e.g., ⅓ of the distance between the hub102and the unflexed position of the member104) and the resulting frequency of the oscillating circuit is measured. That information is stored in a calibration table, as shown in step408. As shown in steps410through416, those steps are repeated as the member is brought through various flexing positions up to the full flexed position (i.e., where the member104contacts the hub102). As shown in step418, data points for flex positions between measured flex positions may be estimated using interpolation, averaging, or other techniques. In some embodiments, the calibration table is normalized to account for the frequency of the oscillating circuit when the member104is in the unflexed position. In other words, in those embodiments the calibration table indicates the frequency change as the member104flexes through various positions.

The steps shown inFIG. 4illustrate data points taken at particular intervals (i.e., ⅓) along the flexing path. Other embodiments may use shorter or longer intervals (e.g., every 5 degrees). Some embodiments may use irregular intervals. In some embodiments, more data points may be taken around particular flex points or regions of flex points. For example, more data points may be taken around the ⅓ flex position than the full flex position in anticipation that calibration data will be used more frequently for flex positions around that ⅓ mark. Still other flex positions may be chosen for additional data because of non-linear effects in the system. In addition,FIG. 4describes steps with respect to a particular oscillating circuit and a particular side of the member (with a particular inductive element). In some embodiments those steps are repeated for each oscillating circuit and its corresponding member side/inductive element. In some embodiments, the steps ofFIG. 4for two or more oscillating circuits are performed concurrently.

FIG. 5illustrates steps that the crop feeler system (e.g., crop feeler system100) may perform to identify and execute a navigational task, according to some embodiments. As shown in step502, the navigation sensor measures the frequency of the oscillating circuits. If the navigation sensor uses a calibration table in which the entries are normalized (e.g., if the entries are altered to account for the oscillating frequencies when the member is in the unflexed position), the frequency measurements may likewise be normalized. As shown in steps504and506, the navigation sensor then identifies an entry (or entries) in the calibration table similar to the measured frequencies and determines a flex position using that entry (or those entries). For example, the measured frequency may be within a predetermined range of a calibration entry (e.g., within 2% of the frequency in the calibration entry), such that the navigation sensor may simply use the flexed position data associated with that calibration entry. If the measured frequency is outside of the predetermined range, then the navigation sensor may use the closest two calibration entries to determine the flex position by taking a simple average of the two calibration entries, using a weighted average system to account for the relative location of the measured frequency with respect to the calibration entries, or may use other interpolation techniques to identify a flex position.

In some embodiments, the navigation sensor is configured to account for temperature variations. For example, the navigation sensor measures the frequency of the oscillating circuits when the member is in the unflexed position and compares those measurements with the corresponding entries in the calibration table. Any differences between those measurements will be largely from changes in temperature of the ferrite cores. The navigation sensor then adjusts the entries in the calibration table based on those differences. In some embodiments, the navigation sensor performs this adjustment multiple times during a measurement session, for example, each time a user indicates the member is in an unflexed position or, if the hubs are located on a boom or on a head of the vehicle, each time the boom or head is lifted.

As shown in step508inFIG. 5, the system identifies a navigational task. In some embodiments the navigational task may be predefined by a user. For example, the navigation sensor may be set to compute the distance from the obstacle to the vehicle and transmit that information to a user interface. In other embodiments, the navigational task may include determining navigational instructions that depend on the flex position. For example, if the member is in a ⅓ flex position, the navigation sensor determines that the navigational task is to steer around the obstacle. If the member is in a full flex position, however, then the navigation sensor determines that the navigational task is to immediately stop the vehicle. In some embodiments, the navigational task depends on the flex positions of both sides of the member. For example, if the left side of the member is in a ⅓ flexed position and the right side is in an unflexed position (either at one moment or over an ensemble of measurements), the navigational instructions determined by the navigation sensor may direct the vehicle to veer to the right. If the left side of the member is in a ⅔ flexed position (either at one moment or over an ensemble of measurements), then the navigational instructions may direct the vehicle to take veer to the right to a greater degree. The navigational instructions may direct the vehicle to change various parameters, such as speed, direction, degree of turn, and/or vehicle-specific parameters. Those instructions are transmitted to the vehicle control system, where the instructions are executed. Executing the navigational instructions may occur automatically or in response to user implementation and/or oversight.