CRAWLER VEHICLE AND CONTROL METHOD OF SAID VEHICLE

A crawler vehicle has a frame; a working tool hinged at the back of the frame around a yaw axis; and actuation system, which is configured to act between the working tool and the frame; and a control device, which is configured to calculate a value of the steering radius of the crawler vehicle and to control the actuation system so as to selectively: enable the working tool to freely oscillate about the yaw axis when the calculated value of the steering radius is comprised within a reference interval; keep the position of the working tool blocked with respect to the frame when the calculated value of the steering radius is outside the reference interval.

PRIORITY CLAIM

This application claims the benefit of and priority to Italian Patent Application No. 102021000027110, filed on Oct. 21, 2021, the entire contents of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a crawler vehicle, in particular used for the preparation of ski runs.

Generally speaking, a crawler vehicle comprises a frame; a pair of motorized tracks; and a working tool coupled to the frame at the back thereof. In case the crawler vehicle is used for the preparation of ski runs, the working tool comprises a tiller assembly, which is dragged by the crawler vehicle on a snowpack of the ski run and comprises a rotary shaft provided with a plurality of teeth to process the snowpack.

BACKGROUND

A relatively ideal preparation of a ski run involves processing the snowpack by the tiller assembly carried by the crawler vehicle to eliminate possible unevenness of the snowpack and make the snowpack relatively aesthetically appreciable.

During the processing of the snowpack, to follow the conformation of the ski run as efficiently as possible, the crawler vehicle needs to make turns, which can have a relatively extremely variable radius. Therefore, known crawler vehicles comprise a connection between the frame and the working tool, which allows the working tool to rotate relative to the frame, so as to prevent the working tool from creating resistances along bends, thus determining a scarce snowpack finishing quality.

European Patent No. 1,405,782 discloses a control system to selectively control the angular position of the working tool connected to the crawler vehicle at the back thereof along bends. In particular, the control system described therein, in response to a steering command, automatically causes the rotation of the working tool around a yaw axis, so that the working tool follows the same trajectory as the crawler vehicle to make it easier for it to steer. However, the control system of European Patent No. 1,405,782 is particularly complicated to be used and installed on a known crawler vehicle and is scarcely reliable, especially in case the crawler vehicle is used for the preparation of a ski run with on a slope.

SUMMARY

An object of the disclosure is to provide a crawler vehicle, in particular for the preparation of ski runs, which reduces certain of the drawbacks of certain of the prior art.

In particular, an object of the disclosure is to provide a crawler vehicle provided with a working tool, which can be used in a relatively simple and reliable fashion for the preparation of ski runs on a slope, so as to ensure a relatively ideal quality of the processed snowpack.

According to the disclosure, there is provided a crawler vehicle, in particular for the preparation of ski runs; the crawler vehicle comprising:a frame extending along a first longitudinal axis;a first and a second motorized track;at least one speed sensor to detect a speed difference between the first track and the second track;a tilt sensor (in certain embodiments) configured to detect a tilt signal indicative of the inclination of the crawler vehicle;a working tool, which extends transversely and symmetrically with respect to a second longitudinal axis and is hinged at the rear of the frame about a yaw axis;an actuation system, which is configured to act between the working tool and the frame; and a control device, which is in communication with said at least one speed sensor and, in certain embodiments, with the tilt sensor and comprises a memory configured to store a reference interval for a steering radius of the crawler vehicle, the control device is configured to:calculate a value of the steering radius of the crawler vehicle, in order to, in certain embodiments, vary the stored reference interval in real time as a function of the detected tilt signal, andcontrol the actuation system so as to selectively perform at least one of:enabling the working tool to freely oscillate about the yaw axis when the calculated value of the steering radius is comprised within the reference interval;keeping the position of the working tool blocked with respect to the frame when the calculated value of the steering radius is outside the reference interval, so that, in certain embodiments, the second longitudinal axis of the working tool is aligned with the first longitudinal axis of the frame.

It should be appreciated that the position of the working tool with respect to the frame can selectively be blocked/released in an automatic, relatively simple and reliable manner, with no need for an intervention of the driver of the crawler vehicle. Furthermore, due to the relative simplicity and reliability of the control device, said control device can be installed on known crawler vehicles.

In more detail, in case the crawler vehicle is used for the preparation of a ski run on a slope and proceeds along a straight trajectory, keeping the position of the working tool blocked, the working tool can be prevented from falling to the side because of its own weight, thus jeopardizing the quality of the processing of the snowpack.

On the contrary, in case the crawler vehicle is used for the preparation of a substantially flat ski run and/or proceeds along a curved trajectory, the free oscillation of the working tool around the frame enables the working tool to follow the same trajectory as the one covered by the crawler vehicle, this avoiding the lateral dragging of the working tool on the snowpack.

A further object of the disclosure is to provide a method to control a crawler vehicle, which reduces certain of the drawbacks of certain of the prior art.

According to the disclosure, there is provided a method to control a crawler vehicle comprising a frame extending along a first longitudinal axis, a first motorized track, a second motorized track, a working tool that extends transversely and symmetrically with respect to a second longitudinal axis and hinged at a rear of the frame about a yaw axis, and an actuation system configured to act between the working tool and the frame, the method comprising:detecting a speed difference between the first motorized track and the second motorized track;detecting a tilt signal indicative of an inclination of the crawler vehicle;storing a reference interval for a steering radius of the crawler vehicle;calculating a value for the steering radius;varying, in real time and based on the detected tilt signal, the stored reference interval; andcontrolling the actuation system to selectively perform at least one of:enabling a free oscillation of the working tool about the yaw axis when the calculated value of the steering radius is within the reference interval; andkeeping the position of the working tool blocked, with respect to the frame and to align the second longitudinal axis of the working tool with the first longitudinal axis of the frame, when the calculated value of the steering radius is outside the reference interval.

DETAILED DESCRIPTION

With reference toFIG.1, number1defines, as a whole, a crawler vehicle, in particular used for the preparation of ski runs.

The crawler vehicle1comprises a frame2extending along a longitudinal axis A1; a track3and a track4, which are both motorized; a speed sensor5and a speed sensor6, each associated with a respective track3,4to detect a speed signal indicative of the speed of said track3,4; a tilt sensor7configured to detect a tilt signal indicative of the inclination of the crawler vehicle1; a working tool8, which extends transversely and symmetrically with respect to a longitudinal axis A2and is hinged at the rear of the frame2around a yaw axis A3; and an actuation system9, which is configured to act between the working tool8and the frame2.

In particular, the speed sensors5and6are configured to detect a speed difference between the track3and the track4.

According to a non-limiting embodiment of the disclosure, each speed sensor5,6is a pressure sensor configured to detect the pressure of a fluid supplied to a respective drive wheel, which determines the movement of a respective track3and4.

In particular, the tilt sensor7is configured to detect a pitch of the crawler vehicle1around an axis perpendicular to the longitudinal axis A1and to the yaw axis A3and to detect a roll of the crawler vehicle1around the longitudinal axis A1.

According to a non-limiting embodiment of the disclosure, the tilt sensor7is a gyroscope.

Furthermore, the crawler vehicle1comprises a shovel10mounted at the front on the frame2; a cabin11mounted on the frame2; and a command unit12, which is arranged inside the cabin11, can be operated by an operator of the crawler vehicle1and is configured to impart a steering command.

In the example described and shown herein, the command unit12comprises a joystick13.

The actuation system9comprises a pair of actuators14configured to act in an opposite manner. In particular, each actuator14is a pneumatic cylinder hinged, at an end, to the frame2and, at the other hand, to the working tool8.

In particular, the working tool8comprises an elongated arm18, which extends along the longitudinal axis A2and is hinged, at an end, to the frame2around the yaw axis A3.

In the non-limiting embodiment of the disclosure described and shown herein, the working tool8comprises a tiller assembly15to process a snowpack of a ski run. In particular, the tiller assembly15comprises a rotary shaft (which is not shown in the figures), provided with a plurality of teeth (which are also not shown in the figures) to process the snowpack.

In the configuration shown inFIG.1, the crawler vehicle1is a snow groomer.

More in detail, the crawler vehicle1is used for the preparation of ski runs for Alpine skiing and/or ski runs for cross-country skiing and/or ramps for ski jumping and/or half-pipes and/or snow-parks.

According to a further embodiment (not shown in the figures), the crawler vehicle1can be used in agricultural operations, such as, for example, the harvesting and/or the handling of agricultural products and/or the ensilage of fodder and/or the harvesting and/or the handling of bagasse. In this configuration, the working tool8is configured to process the agricultural products laid on the ground. Furthermore, according to a further embodiment (which is not shown in the figures), the crawler vehicle1comprises a mulcher arranged on the front side of the vehicle and can be used to mulch plants.

With reference toFIG.1, the crawler vehicle1comprises a control device16, which is in communication with the speed sensors5and6and with the tilt sensor7and comprises a memory17configured to store a reference interval for a steering radius of the crawler vehicle1.

The control device16is configured to calculate a value of the steering radius of the crawler vehicle1to, in certain embodiments, vary the stored reference interval in real time as a function of the detected tilt signal, and to control the actuation system9so as to selectively:enable the working tool8to freely oscillate about the yaw axis (A3) when the calculated value of the steering radius is comprised within the reference interval; andkeeping the position of the working tool8blocked with respect to the frame2when the calculated value of the steering radius is outside the reference interval, so that the longitudinal axis A2of the working tool8is aligned with the longitudinal axis A1of the frame2.

In particular, the command unit12is in communication with the control device16so as to transmit, to the control device16, a steering signal indicative of the imparted steering command.

With reference toFIG.2, the control device16is configured to calculate the value of the steering radius as a function of the speed signals detected by the speed sensors5and6and to control the actuation system9as a function of said speed signals.

Furthermore, the control device16is configured to vary the stored reference interval in real time as a function of the speed signals detected by the speed sensors4and5.

With reference toFIG.3, the control device16is configured to control the actuation system9so as to selectively bring the working tool8gradually back into alignment with the frame2when the value of the calculated steering radius does not fall within the reference interval.

The control device16is configured to align the longitudinal axis A2of the working tool8with the longitudinal axis A1of the frame2. In particular, the control device16is configured to calculate a theoretical steering trajectory as a function of the imparted steering command and of the detected speed signals and to control the actuation system9so as to selectively bring the working tool8back into alignment with the frame2following said calculated theoretical trajectory when the calculated value of the steering radius does not fall within the reference interval.

In more detail, the control device16is configured to calculate, as a function of the detected speed signals, a time delay interval, which elapses between the time instant in which the calculated value of the steering radius falls within the reference interval and the time instant of activation of the actuation system9to bring the working tool8back into alignment with the frame2. The control device16is configured to control the actuation system9with a delay equal to the calculated time delay interval.

In use and with reference toFIG.2, a reference interval for a steering radius of the crawler vehicle1is stored in the memory17(block19). In particular, said reference interval is defined for the purpose of preventing the activation of the actuation system9with every relatively small steering correction by a driver of the crawler vehicle1.

While the crawler vehicle1proceeds on a ski run to be processed, the speed sensors5and6detect the speed of the tracks3and4respectively (blocks20and21) and the tilt sensor7detects the inclination of the crawler vehicle1(block22). In particular, the inclination sensor7detects a pitch angle and a roll angle, each defined with respect to a Cartesian reference system having two axes belonging to an ideal horizontal plane.

The control device16calculates a moving speed (block23) of the crawler vehicle1and a steering radius value (block24) of the crawler vehicle1as a function of the detected speeds of the tracks3and4.

Subsequently, starting from the stored reference interval, the control device16calculates a variation in the reference interval (block25) as a function of the detected inclination of the crawler vehicle1and of the calculated speed of the crawler vehicle1.

By way of example, when the crawler vehicle1proceeds downhill along a ski run on a slope, the control device16reduces the reference interval with respect to the situation in which the crawler vehicle1moves along a substantially flat ski run, so as to prevent the working tool8from falling to the side because of its own weight.

On the contrary, as the moving speed of the crawler vehicle1increases, the control device16widens the reference interval in order to avoid excess stresses for the working tool8.

At this point, the control device16compares the calculated steering radius value with the reference interval (block26).

In case the calculated value of the steering radius is outside the reference interval, the control device16controls the actuators14so as to keep the position of the working tool8with respect to the frame2blocked (block27). In particular, the actuators14keep the longitudinal axis A2of the working tool8aligned with the the longitudinal axis A1of the frame2.

On the contrary, in case the calculated value of the steering radius is within the reference interval, the control device16controls the actuators14so as to enable or allow the working tool8to freely oscillate around the yaw axis A3(block28).

With reference toFIG.3, in case the calculated value of the steering radius is outside the reference interval, the control device16evaluates whether the longitudinal axis A2of the working tool8is aligned with the longitudinal axis A1of the frame2(block29).

If the longitudinal axis A2of the working tool8is aligned with the longitudinal axis A1of the frame2, the control device16controls the actuators14so as to keep the position of the working tool8with respect to the frame2blocked (block27).

If the longitudinal axis A2of the working tool8is not aligned with the longitudinal axis A1of the frame2, the control device16detects the steering command (block30) imparted by the command unit12.

Subsequently, the control device16calculates a theoretical steering trajectory (block31) and a time delay interval (block32) as a function of the speed signals detected by the speed sensors5and6and as a function of the detected steering command.

In particular, the time delay interval elapses between the time instant in which the calculated value of the steering radius falls within the reference interval and the time instant of activation of the actuation system9to bring the working tool8back into alignment with the frame2. Said time delay interval has the function of preventing the working tool8from going back into alignment with the frame2too quickly, thus determining a scarce quality of processing of the snowpack.

Once the time delay interval and the theoretical steering trajectory have been calculated, the control device16activates the actuators14so as to bring the working tool8back into alignment with the frame2(block33) following said theoretical trajectory calculated with a delay that is equal to the calculated time delay interval.

At this point, the control device16controls the actuators14so as to block the position of the working tool8with respect to the frame2(block27).

FIG.4shows the crawler vehicle1while driving along a bend with a steering radius R, which is comprised within the reference interval. In this operating configuration, the working tool8is free to oscillate around the yaw axis A3so as to follow the trajectory of the bend.

FIG.5shows the crawler vehicle1while moving along a given or designated trajectory having a plurality of segments T1, T2, T3and T4.

In particular, along the straight segment T1, the actuation system9keeps the position of the working tool8blocked with respective to the frame2. Under this circumstance, the longitudinal axis A2of the working tool8is aligned with the longitudinal axis A1of the frame2.

Along the curved segment T2, the value of the steering radius is within the reference interval and the control device16controls the actuation system9so as to enable the working tool8to freely oscillate around the yaw axis A3.

When shifting from the curved segment T2to the straight segment T3, the value of the steering radius is outside the reference interval. Under this circumstance, the control device16controls the actuation system9so as to gradually bring the working tool8back into alignment with the frame2. In particular, the control device16controls the actuation system9so as to bring the working tool8back into alignment with the frame2following a calculated theoretical trajectory and with a delay that is equal to a calculated time delay interval.

Once they are aligned, the actuation system9keeps the position of the working tool8blocked with respect to the frame2for the entire length of the straight segment T3.

Along the segment T4, the value of the steering radius goes back to falling within the reference interval and, as a consequence, the control device16controls the actuation system9so as to enable again the working tool8to freely oscillate around the yaw axis A3. In this way, the working tool8is capable of following the trajectory determined by the series of bends in succession of the segment T4.

Finally, the disclosure can evidently be subjected to variants, though without going beyond the scope of protection set forth in the appended claims. That is, the present disclosure also covers embodiments that are not described in the detailed description above as well as equivalent embodiments that are part of the scope of protection set forth in the claims. Accordingly, various changes and modifications to the presently disclosed embodiments will be apparent to those skilled in the art.