Autonomous Backfilling Apparatus

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.

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 hopperof, 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, a work machineis shown. The work machinecomprises a material hopperdisposed below a material mixer. The mixeris supported by ground engaging members such as wheels. A chassisis attached to the mixer, and may provide power to various components of the machineand provide a location for an operator to control the machine, such as control station.

The material hopperhas a ground-contacting surfaceat its bottom. This surfacemay act as a skid surface, such that the outlet of the hoppermay ride on, or just above, a ground surface.

A slot is formed in the surface, allowing material from the hopperto flow into a trench formed in a ground surface. A tabmay extend from the hopper, beyond the surface of the ground into the trench. The tabenables the slot in surfaceto remain over the trench.

The material hoppersupports three sensors,,. The first sensoris disposed in line with the slot within the surface. The first sensoris placed ahead of the surfacein a direction of travel. The first sensor, which may comprise any of the types of sensors mentioned above (or a combination thereof), will provide two main functions. First, the first sensormay, using a calibration line perpendicular to the trench, determine whether the machineis properly aligned. If the machineis 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.

The second sensoris behind the hopperin the direction of travel. Thus, the second sensorcan detect whether or not the trench is overfilled or underfilled. In the case of an underfilled trench, the machinemay 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, as the speed should be matched to the volumetric flowrate needed to fill a trench from the hopper. The more slowly a machinetravels, the higher the level of fill in the trench that is overlaid by the material hopper, assuming constant flowrate from the hopper.

The third sensoris disposed above the hopperto prevent the hopperfrom overfilling, or from running dry. When the sensordetects that the level of material in the hopperis too low, more material must enter the hopper. Fill material is mixed and stored at a mixer. The processor thus directs a gateon the material mixerto open, or to increase the area which is open. A linear actuatorcontrols the position of the gate. When the third sensordetects that the hopperis in danger of overfilling, it closes the gateor reduces the open area.

In addition, sensormay be capable of two additional functions. First, fine differences in the height of material in the hoppermay increase, or decrease, the rate at which the trench is filled due to the weight of material. The sensorcan 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 machinemay detect that an end of the trench is approaching. In this situation, the third sensormay be utilized to ensure that the trench is filled with no excess material remaining in the hopper. Excess material in the hoppermust be cleaned to avoid drying and clogging the hopper.

In operation all the sensors,,work together with a processor to control functions of the machine. In general, the second sensorwill sense the depth of fill of the backfill in the trench, which will control the drive motors of ground engaging motive members (such as wheelsor, alternatively, tracks) of the machine. The first sensormay 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 sensormay develop a singular reading or an array of readings to measure the amount of backfilling material in the hopper. 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, a flow chart is shown demonstrating this control logic. The process starts at. The machineis aligned and sensors are calibrated at. At, the first sensordetermines if the machineis aligned. If not, steering corrections are provided atand wheels(or other motive force members) are adjusted in accordance with the adjustment.

At, the second sensordetermines the level of fill in the trench. If too little, the machine may dwell and reverse at, 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, the third sensordetects whether or not the hopperis properly loaded. If not, the gateis opened from mixerto increase the hopper level at, or is closed (either fully or partially) to decrease the hopper level.

At, the process continues while the machineis in operation and the hopperis 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.