BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top view of the automatic self-centering duct robot of the instant invention within a duct or conduit;
FIG. 2 is a schematic diagram of the control system of the automatic self-centering duct robot of the instant invention;
FIG. 3 is a top view of a second embodiment of the automatic self-centering duct robot of the instant invention; and
FIG. 4 is an isometric view of the self-centering duct robot of the instant invention within a duct.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to the drawings, FIGS. 1 through 4, there is shown the preferred embodiment of the automatic self-centering duct robot of the instant invention. The instant invention is shown and described below as a device to be used to clean and maintain HVAC ducts and conduits, but, without changing the spirit of the invention, the device could be used for a wide variety of other purposes.
Now referring to FIG. 1, a top view of the automatic self-centering duct robot of the instant invention within a duct is shown. For description purposes, the top of the figure is considered to be forward. The robot 2 includes a platform 4 which has four wheels, one affixed near each corner of the platform 4. A front drive wheel 6 is affixed to the left front of said platform 4 and a rear drive wheel 8 is affixed to the right rear of said platform 4. Both the front drive wheel 6 and the rear drive wheel 8 are powered by conventional electric motors (not shown). The other two wheels are not powered. The electric motors are capable of being turned at a variety of speeds and in either direction. As will be easily understood, by controlling the electric motors and the speed and direction of rotation of said front drive wheel 6 and said drive wheel 8, the robot 2 can be moved in any direction and even rotated without moving. Although the device is described as having powered wheels at the left front and the right rear, the device could be configured to work properly as long as any two wheels are independently controlled. Although the device is described as having wheels driven by electric motors, any of a number of other means of propulsion belts, tracks, legs, or fins could be used.
Still referring to FIG. 1, four distance sensors are affixed at the comers of said platform 4. Sensor 10 is located at the right front corner, sensor 12 is located at the left front corner, sensor 14 is located at the left rear corner, and sensor 16 is located at the right rear corner. The sensors are conventional infrared sensors, but any of a variety of other types of conventional sensors including cameras with sensors could be used. Said robot 2 is located within a duct or conduit and the right side of the duct is shown as right duct side 18 and the left side of the duct is shown as left duct side 20. With the longitudinal axis of said platform 4 parallel to right duct side 18 and left duct side 20 as shown, sensor 10 points forward and right at forty-five degrees to a centerline 22 through the center of the duct. Sensor 12 points forward and left at forty-five degrees to the centerline 22, sensor 14 points rearward and left at forty-five degrees to said centerline 22, and sensor 16 points rearward and right at forty-five degrees to said centerline 22. Thus, all these sensors are directed at forty-five degrees from the longitudinal axis of said platform 4 and ninety degrees to each other. In addition to the four sensors described above, there is a sensor 17 located on the top surface of said platform 4 which is directed upward. The sensor 17 measures the distance between the top surface of said platform 4 and the bottom surface of the top of the duct or conduit. By using said sensor 17 in combination with the other four sensors, any movable attachment to said robot 2 could be located and controlled in three dimensions.
Still referring to FIG. 1, the sensors paths are shown as path 24 for said sensor 10, path 26 for said sensor 12, path 28 for said sensor 14, and path 30 for said sensor 16. Sensor 10, for example, sends an infrared signal along path 24 which hits said right duct side 18 and returns. Said sensor 10 determines the time it takes for the signal to reach said right duct side 18 and return and, thus, is capable of determining the distance of said path 24. Similarly, the other sensors determine the distances of said paths 26, 28, and 30. As, for example, the length of path 24 is known and as a line from said sensor 10 and said right duct side 18 which is at a right angle to said right duct side 18 can be used to determine the distance of said robot 2 from said right duct side 18, the Pythagorean theorem may be used to easily determine the distance from said sensor 10 to said right duct side 18. In actual practice, said robot 2 can be moved forward along said centerline 22 by subtracting the distance of said path 24 from said path 26 and controlling the electric motors on said front drive wheel 6 and said rear drive wheel 8 such that the difference approaches zero. The simple formula: rate times time equal distance is used remembering that the distance traveled along, for example, said path 24 is double the actual distance between said sensor 10 and said right duct side 18 because said path 24 is actually from said sensor 10 to said right duct side 18 and back to said sensor 10. The same process may be used when said robot 2 is operated in reverse by subtracting the distance of said path 28 from said path 30. Of course other formulas and calculations could be used.
Referring now to FIG. 2, a schematic diagram of the control system of the automatic self-centering duct robot of the instant invention is shown. A conventional analog to digital converter 40 receives the signals from said sensors 10, 12, 14, 16, and 17 and converts the analog signals from the sensors into digital data. A conventional microcontroller 42 includes an error calculation function 44 and a motor controller function 46. The error calculation function 44 calculates either the difference between the distance measured by said sensors 10 and 12 for forward motion or the difference between the distance measured by said sensors 14 and 16 for rearward motion of said robot 2. The motor controller function 46 uses input from said error calculation function 44 to cause the difference between the distance between said robot 2 and said left duct side 20 and said right duct side 18 to approach zero by controlling the motor drivers 48. The motor drivers 48 control the speed of the electric motors driving said front drive wheel 6 and said rear drive wheel 8. The above described self-centering capability of said robot 2 may be activated by powering up the infrared sensors remotely or manually before said robot 2 is inserted into the duct. The input from said sensor 17 may be used in conjunction with the other four sensors to locate and control any movable attachment to said robot 2 in three dimensions.
Still referring to FIG. 2, the analog to digital converter 40 may be integrated into said microcontroller 42. In the preferred embodiment, a conventional proportional-integral-derivative controller (PID controller) is used. However, a simpler controller could be used, because the integral and derivative functions of a standard PID controller are not used for this application. Other, advanced, control systems such as Fuzzy logic, an artificial neural network, expert systems, or some combination of them could also be used. It will be understood that it would be relatively simple to program the instant invention such that said robot 2 travels along a line in either direction which is offset by a specified distance from said centerline 22. For example, if it were desired to offset by 10 centimeters to the left of said centerline 22, the error is calculated using this offset by adding it to the measurement from said sensor 12 and said sensor 14 measurement before subtracting. In summary, the system of the instant invention uses sensors to continuously calculate the distances to the nearest interior surface and corrects the position of said robot 2 within the duct.
Referring now to FIG. 3, a top view of a second embodiment of the automatic self-centering duct robot of the instant invention is shown. This embodiment is intended to show that the instant invention could be modified in a variety of ways and still function within the spirit of the invention. In this embodiment duct side 50 is on the right side of a second robot 56 and a duct side 52 is on the left side. Rather than being directed forward and to the right as described above for said sensor 10, a sensor 60 points rearward and to the right at a forty-five degree angle to the duct side 50 and a sensor 62 points forward and to the right. Sensor 64 and sensor 66 are directed toward a duct side 52 at right angles to the longitudinal axis of the second robot 56 from the forward end and the rearward end of said second robot 56 respectively. It would be relatively simple to use the Pythagorean theorem and a microcontroller as described above to determine the position of said robot 56 using the distance measured using sensor 64 and sensor 60 when moving forward and using sensor 62 and sensor 66 when moving rearward. Various other configurations of sensors could be used to achieve the same result. This figure also shows an offset path 70 which may be offset from the centerline of the duct on either side. As described above, it would be relatively simple to control either said robot 2 or said second robot 56 such that they traveled along such an offset path 70. This would be useful if, for example, there was an attachment to the robot and it was preferable to have the attachment travel down the centerline with the robot off to one side.
Referring now to FIG. 4, an isometric view of the self-centering duct robot of the instant invention within a duct is shown. The robot 72 is shown as being inside a rectangular duct 74. In this view there may be seen that the robot 72 is connected to a tether 76. The operating system (not shown, but described above) is connected to the other end of the tether 76 and the signals controlling the motors described above also travel through said tether 76. Said tether 76 may also be used to recover said robot 72 from within the rectangular duct 74. In this figure said robot 72 may represent either said robot 2 or said second robot 56 as described above. Depending upon operator input through said tether 76, may be used to operate said robot 72 either forward or backward through said rectangular duct 74 either along the centerline of said rectangular duct 74 or along some offset to the centerline. The speed of said robot 72 through said rectangular duct 74 may be either preset or operator controlled in the event that video feedback is supplied in the form of a forward facing and a rearward facing camera affixed to said robot 72. In addition, a variety of cleaning or maintenance tools could easily be affixed to said robot 72.
All elements of the automatic self-centering duct robot are made of stainless steel and delren except for those described below, but other material having similar strength and stiffness could be used. Said platform 4 is specifically manufactured for the instant invention, but all other elements including wheels, axles, sensors, motor drivers, and the microcontroller are all conventional and easily obtained from a variety of sources.
While preferred embodiments of this invention have been shown and described above, it will be apparent to those skilled in the art that various modifications may be made in these embodiments without departing from the spirit of the present invention.
Patent Application
20080012310
