AUTONOMOUS BACKFILLING APPARATUS

Description

SUMMARY

The present invention is directed to a method. The method comprises uncovering a trench with a microtrencher and following the trench with a trench filling machine containing a fill material. At a first location on the trench filling machine, a path of the trench is detected and sent to a processor as a first signal. At a second location on the trench filling machine, a level of the fill material in the hopper is detected and a second signal is sent to the processor as a second signal. At a third location on the trench filling machine, a level of fill material in the trench is detected and sent to the processor as a third signal.

In response to the first, second and third signals, a speed and orientation of the trench filling machine may be adjusted.

In another aspect, the present invention is directed to a trench filling apparatus. The trench filling apparatus comprises a frame, a motive force member supporting the frame, and a fill material container supported by the frame. A hopper is supported by the frame and has an upward-facing opening and a surface engaging member. A slot is formed in the surface engaging member.

The apparatus also comprises a first, second and third sensor. The first sensor is disposed on a first side of the slot. The second sensor is disposed on a second side of the slot, and the third sensor is disposed above the upward-facing opening. A processor is configured to receive a first signal from the first sensor, a second signal from the second sensor, and a third signal from the third sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a hopper having various sensors for use with a trench filling apparatus.

FIG. 2 is a back side top perspective view of a machine including the hopper of FIG. 1.

FIG. 3 is a process flow chart related to the present invention.

DETAILED DESCRIPTION

A microtrenching machine uses a large wheel equipped with cutting teeth to generate narrow trenches in materials such as asphalt and concrete for product installation. Such a microtrenching machine is disclosed in U.S. Pat. No. 8,806,784, the contents of which are incorporated herein by reference. Backfilling these trenches is often tedious and requires ample skill. Autonomous machines, equipped with various types of sensors can follow trenches accurately and control the rate of backfill to prevent overfilling and maintain alignment. Such a backfilling machine is disclosed in U.S. Pat. No. 10,309,080, the contents of which are incorporated herein by reference.

Line following and distance measuring sensors operate using various means such as lasers or ultrasonic signals that measure the time of flight to determine distance and position. Others use means such as reflected infrared light to measure reflectivity to locate markers. This disclosure seeks to use this robust technology to automate a machine that follows trenches using sensors or other guidance instruments and backfill trenches to a given target. The backfill will be controlled using various sensors and controllers that start and stop the backfill flow according to desired outputs.

While the word “automation” or “automatic” is used herein, the sensor system described herein may also provide operator assistance. For example, a small LCD or LED array may provide a visual indicator based upon the signals received by various sensors, providing direction and assistance to an operator, rather than causing the machine to operate autonomously. Such a distinction is not a departure from the spirit of the invention.

When sensors are discussed herein, it should be understood that the sensors may be one or more of Light Detection and Ranging (LiDAR), ultrasonic sensors, infrared (IR) sensors, position sensors, touch sensors, or other known technologies.

It is preferred for a trench in a roadway surface to be filled to its top. However, a slight underfill, though it creates a surface irregularity, is preferable to a slight overfill, as any fill material that overflows a trench will need to be cleaned off. Further, grout material—often concrete—is susceptible to viscosity changes which will make flow of material out a hopper, such as the hopper 10 of FIGS. 1-2, somewhat unpredictable. Therefore, the sensors of the present invention must be utilized in a manner which allows unexpected outcomes to be detected, corrected, and for adjustments to be made with processes going forward.

With reference to FIGS. 1-2, a work machine 100 is shown. The work machine 100 comprises a material hopper 10 disposed below a material mixer 36. The mixer 36 is supported by ground engaging members such as wheels 30. A chassis 40 is attached to the mixer 36, and may provide power to various components of the machine 100 and provide a location for an operator to control the machine, such as control station 42.

The material hopper 10 has a ground-contacting surface 21 at its bottom. This surface 21 may act as a skid surface, such that the outlet of the hopper 10 may ride on, or just above, a ground surface.

A slot is formed in the surface 21, allowing material from the hopper 10 to flow into a trench formed in a ground surface. A tab 12 may extend from the hopper 10, beyond the surface of the ground into the trench. The tab 12 enables the slot in surface 21 to remain over the trench.

The material hopper 10 supports three sensors 22, 23, 24. The first sensor 22 is disposed in line with the slot within the surface 21. The first sensor 22 is placed ahead of the surface 21 in a direction of travel 50. The first sensor 22, which may comprise any of the types of sensors mentioned above (or a combination thereof), will provide two main functions. First, the first sensor 22 may, using a calibration line perpendicular to the trench, determine whether the machine 100 is properly aligned. If the machine 100 is not properly aligned, a steering correction may be provided. Second, a depth of the trench may be detected. Changes in the depth of the trench may necessitate changes in the flowrate out of the hopper 10.

The second sensor 23 is behind the hopper 10 in the direction of travel 50. Thus, the second sensor 23 can detect whether or not the trench is overfilled or underfilled. In the case of an underfilled trench, the machine 100 may be directed to slow or, when more fill is needed, reverse and dwell over the trench at the underfilled location.

In most situations the fill level of the trench may indicate the need for small fluctuations in the ground speed of the machine 100, as the speed should be matched to the volumetric flowrate needed to fill a trench from the hopper 10. The more slowly a machine 100 travels, the higher the level of fill in the trench that is overlaid by the material hopper 10, assuming constant flowrate from the hopper.

The third sensor 24 is disposed above the hopper 10 to prevent the hopper 10 from overfilling, or from running dry. When the sensor 24 detects that the level of material in the hopper 10 is too low, more material must enter the hopper. Fill material is mixed and stored at a mixer 36. The processor thus directs a gate 34 on the material mixer 36 to open, or to increase the area which is open. A linear actuator 35 controls the position of the gate 34. When the third sensor 24 detects that the hopper 10 is in danger of overfilling, it closes the gate 34 or reduces the open area.

In addition, sensor 24 may be capable of two additional functions. First, fine differences in the height of material in the hopper 10 may increase, or decrease, the rate at which the trench is filled due to the weight of material. The sensor 24 can detect and communicate this level to a processor, which may attempt to maintain a constant level of grout (or to increase or decrease the level as needed for project parameters).

Second, sensors on the machine 100 may detect that an end of the trench is approaching. In this situation, the third sensor 24 may be utilized to ensure that the trench is filled with no excess material remaining in the hopper 10. Excess material in the hopper 10 must be cleaned to avoid drying and clogging the hopper.

In operation all the sensors 22, 23, 24 work together with a processor to control functions of the machine 100. In general, the second sensor 23 will sense the depth of fill of the backfill in the trench, which will control the drive motors of ground engaging motive members (such as wheels 30 or, alternatively, tracks) of the machine 100. The first sensor 22 may develop an array of readings to find both edges of the trench and maintain center alignment while backfilling the trench. As discussed, it may also detect changes in depth to anticipate a change of speed. The third sensor 24 may develop a singular reading or an array of readings to measure the amount of backfilling material in the hopper 10. As discussed above, these functions may take automatically, or after signals are provided to an operator as a part of an operator assistance protocol.

With reference to FIG. 3, a flow chart is shown demonstrating this control logic. The process starts at 102. The machine 100 is aligned and sensors are calibrated at 104. At 106, the first sensor 22 determines if the machine 100 is aligned. If not, steering corrections are provided at 108 and wheels 30 (or other motive force members) are adjusted in accordance with the adjustment.

At 110, the second sensor 23 determines the level of fill in the trench. If too little, the machine may dwell and reverse at 112, allowing the trench to better fill. Likewise, if overfilled, the machine may speed up or lower the level of material within the hopper to reduce the fill level.

At 114, the third sensor 24 detects whether or not the hopper 10 is properly loaded. If not, the gate 34 is opened from mixer 36 to increase the hopper level at 116, or is closed (either fully or partially) to decrease the hopper level.

At 118, the process continues while the machine 100 is in operation and the hopper 10 is being used to fill in a trench.

The various features and alternative details of construction of the apparatuses described herein for the practice of the present technology will readily occur to the skilled artisan in view of the foregoing discussion, and it is to be understood that even though numerous characteristics and advantages of various embodiments of the present technology have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the technology, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present technology to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.