Combined ultrawide band and inertial motion unit position detection and control

Abstract

A method including the steps of providing a plurality of ultrawide band ("UWB") components including a transmitter and / or a receiver at a first location, and at a second location, and communicating with a control on one of said first and second locations, sending radial frequency signals from at least one of the UWB components at one of the first and second locations to a second UWB components on the other of the first and second locations, and receiving a reflective signal at the at least one UWB component, and determining an UWB relative position of the first and second locations in at least two dimensions, determining the relative position of the first and second locations utilizing an inertial motion unit ("IMU"), sending the IMU determined position to the control and considering the ultrawide band determined relative position and the IMU determined relative position to reach a final position determination.

Description

COMBINED ULTRA WIDE BAND AND INERTIAL MOTION UNIT POSITION DETECTION AND CONTROLRELATED APPLICATION(S)

[0001] This application claims the benefit of United States Provisional Application No. 63 / 659,045, filed June 12, 2024, the entirety of which is incorporated by reference.BACKGROUND

[0002] This application relates to a method of utilizing ultrawide band radio signals in combination with inertial motion unit signals to detect relative position, and for controls utilizing the detected position.

[0003] Modern industrial systems are becoming increasingly complicated and require sophisticated controls. Within a single machine it becomes necessary to know the position of moving parts relative to other areas on the machine.

[0004] Further, machines are often operated in combination with each other. There have been inadequate controls to tie the operation of the related machines to each other.

[0005] Ultrawide band (“UWB”) detection systems are known. However, the potential has not been fully developed.

[0006] Inertial motion units (“IMU”) are also known. An inertial motion unit is an electronic device that measures and reports a body’s force, angular movement, orientation and location using a combination of accelerometers and gyroscopes. IMUs are typically used to maneuver modern vehicles. An IMU works by detecting linear acceleration using one or more accelerometers and rotational rate using one or more gyroscopes. They are utilized to calculate attitude, angular rates, linear velocity and position relative to a global reference frame.SUMMARY

[0007] In a featured embodiment, a method including the steps of providing a plurality of ultrawide band (“UWB”) components including a transmitter and / or a receiver at a first location, and including a transmitter and / or receiver at a second location, with at least one of the UWB components communicating with a control on one of said first and second locations, sending radial frequency signals from at least one of the UWB components at one ofthe first and second locations to a second UWB components on the other of the first and second locations, and receiving a reflective signal at the at least one UWB component, and determining an UWB relative position of the first and second locations in at least two dimensions, determining the relative position of the first and second locations utilizing an inertial motion unit (“IMU”), sending the IMU determined position to the control and considering the ultrawide band determined relative position and the IMU determined relative position to reach a final position determination.

[0008] In another embodiment according to the previous embodiment, the first and second locations are on a single machine with one of said locations moving relative to the other of said locations.

[0009] In another embodiment according to any of the previous embodiments, a tool on the single machine moves relative to a second portion of the single machine, and the tool and the second portion provide the first and second locations.

[0010] In another embodiment according to any of the previous embodiments, the relative position is in only two dimensions.

[0011] In another embodiment according to any of the previous embodiments, there is also an angular relationship between the first and second locations that is determined.

[0012] In another embodiment according to any of the previous embodiments, the relative position is determined in three dimensions.

[0013] In another embodiment according to any of the previous embodiments, the relative position includes an angular relationship between the first and second locations.

[0014] In another embodiment according to any of the previous embodiments, the locations are mounted on distinct machines, and the control is operable to coordinate operation between the two machines based upon on the determined relative position of the two locations.

[0015] In another embodiment according to any of the previous embodiments, the relative position is in only two dimensions.

[0016] In another embodiment according to any of the previous embodiments, there is also an angular relationship between the first and second locations that is determined.

[0017] In another embodiment according to any of the previous embodiments, the relative position is determined in three dimensions.

[0018] In another embodiment according to any of the previous embodiments, the relative position includes an angular relationship between the first and second locations.

[0019] In another embodiment according to any of the previous embodiments, one of the machine is a device carried by a user and the other of the machines is a vehicle being controlled to approach the user’s location.

[0020] In another embodiment according to any of the previous embodiments, the device is in a hat, and communicates with the vehicle.

[0021] In another embodiment according to any of the previous embodiments, the IMU includes accelerometer, magnetometers and gyros.

[0022] In another embodiment according to any of the previous embodiments, dependent on the absolute distance between the first and second location the relative weight afforded to the UWB determined relative position and the IMU determined relative position is varied.

[0023] In another embodiment according to any of the previous embodiments, if the absolute distance is relatively great, then the IMU determined relative position is given more weight.

[0024] In another embodiment according to any of the previous embodiments, if the relative position is relatively smaller than the UWB determined relative position is provided with more weight.

[0025] In another embodiment according to any of the previous embodiments, if the relative position of the first and second location is not changing, the UWB component is shutdown as an energy saving step.

[0026] In another embodiment according to any of the previous embodiments, the UWB signals are greater than or equal to 450 MHz.

[0027] These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A schematically shows a movement detection system along a single axis.

[0029] Figure IB schematically shows an inertial motion unit.

[0030] Figure 1C schematically shows the operation of a position sensor.

[0031] Figure 2A schematically shows position detection in a two-dimensional space.

[0032] Figure 2B schematically shows relative position sensing in a two- dimensional plane, and wherein the pose of the two components is detected.

[0033] Figure 2C shows a two-dimensional example.

[0034] Figure 3A schematically shows a system for detecting relative position in three dimensions.

[0035] Figure 3B schematically shows a system for detecting relative position in three dimensions and wherein the pose between the two components can be detected.

[0036] Figure 4A shows a first application for the position detection on a single machine.

[0037] Figure 4B shows an example similar to Figure 4A.

[0038] Figure 5 shows an application use and position detection for a safety device.

[0039] Figure 6 shows an application wherein a relative position between two machines is determined.

[0040] Figure 7 is a flowchart of a method according to this disclosure.DETAILED DESCRIPTION

[0041] Figure 1 A shows a single machine 20, which may be a tool having a moving tool component 26 which moves telescopically relative to a static base 24. A UWB transmitter / sensor 22 is associated with the static structure 24, as is a control 23. As shown, the tool has a UWB sensor 28, that may also be a transmitter.

[0042] UWB signals can be defined as being in a frequency range greater than or equal to 450 MHz, and in some applications greater than or equal to 500 MHz.

[0043] An inertial motion unit (“IMU”) 27 is shown on the moving element 26. IMU 27 also communicates with control 23. As the tool 26 moves, such as to the position 30 as shown in phantom, the two UWB components 22 and 28 communicate with each other such that the control 23 is provided with exact position information of the tool 26. The IMU 27 also determines position and control 23 uses the IMU and UWB signals to refind the position detection.

[0044] An inertial motion unit 27 is schematically illustrated in Figure IB. As shown, mounting frames 15 mount an IMU 27 to various parts as disclosed above, and below. There is a roll mount 16 between a first element 17 and the static structure 15. There is a pitch mount 18 between structure 17 and inner structure 19. There is an azimuth mount 11 between inner structure 19 and a static base 13. Accelerometers 25, magnetometers 29 and gyros 21 determine movement, etc, in three different axes. The structure and operation of IMU 27 may be as known. It is a unique use of determined position signals which is disclosed here.

[0045] As disclosed below, depending on whether one is determining position in a single dimension, two dimension, or three dimensions less complex or more complex IMUs 27 may be utilized.

[0046] As known, and as shown schematically in Figure 1C, the receiver transmitter 22 may send a signal to the receiver / transmitter 28 which is then reflected back. Simple mathematical relationships may then be utilized to determine a distance between the UWB components 22 and 28, and hence between the tool 26 and the static base 24. Similarly, IMU 27 also communicates with control 23.

[0047] IMU in electronics design commonly refers to MEMS (Micro - Electro - Mechanical System) IMU. 3 axis MEMS IMU commonly refers to 3 axis (x,y,z) accelerometer. 6 axis MEMS IMU refers to 3 axis accelerometer + 3 axis (pitch, yaw, roll) gyroscope. 9 axis MEMS IMU refers to 3 axis accelerometer + 3 axis gyroscope + 3 axis magnetometer. This disclosure uses 6 axis IMU for ID positioning application and need 9 axis IMU for 2D / 3D positioning application.

[0048] Figure 2A extends the concept to determining the relative position between parts 40 and 42 in a two-dimensional plane. As shown, part 42 has a UWB transmitter / receiver 44 communicating with a control 45. The part 40 may have a control 41 communicating with UWB transmitters / receivers 46, 48 and 50. The UWB component 44 communicates to each of the components 46, 48 and 50 and their relative position is determined. Since the components 46, 48 and 50 are at known positions on the part 40, the sensing between the UWB components 44 and each of 46, 48 and 50 provide accurate relative position information to the control 45. IMU 43 also communicates position information to control 45.

[0049] The two parts here could be on the same vehicle, with one of the two parts being a moving tool, in which case a dedicated control need not be associated with that part. On the other hand, this would also extend to two distinct machines being the parts 40 and 42.

[0050] Figure 2B shows an application wherein the relative position between parts 40 and 51 is determined within two-dimensional planes. However, the “pose” or angular orientation (angle A) between two parts 40 and 51 may also be determined. Here, part 40 is provided with a control 41 and UWB transmitters / sensors 46, 48 and 50. The part 51 is provided with two UWB transmi tters / recei vers 52 and 53, each communicating with a control 54. By knowing the relative position between the two UWB components 52 and 53 and then each of the UWB transmitters / receivers 46, 48 and 50, the control 54 (or 41 or both), can determine not only the position within the two-dimensional plane, but also the “pose.” IMU 55 also communicates position to control 54.

[0051] 2D / 3D positioning is similar to ID application but consider from ID, we integrate acceleration a in ID space, but in 2D / 3D, we need to integrate acceleration a in 2D / 3D space. Here is an example in 2D application as shown in Figure 2C.

[0052] A small machine is moved from A to B. First, UWB position is contained as it moved as explained above. Second, acceleration is obtained to compute the IMU position, similar with the ID based on the reading from accelerometer and gyro. But the problem here is the gyro is not directly providing the angle theta 0, which can be read from the gyro angle velocity, and one then integrates the angle velocity to get theta 0. Angle velocity always has small error and if integrated for a long time, it will accumulate the error and will cause theta 0 drifting. Connecting this is critical for accurate calculate position, since if your direction is wrong, your determined position is wrong. A magnetometer provides an absolute reference to north, so, it is needed to correct the theta 0 drifting. The theta 0 drifting is not a problem in ID, because in ID, if boom is not moved (B not moved), the gravity is highly related with theta 0, so, one can use the gravity direction as absolute reference to correct the theta 0 drifting. While in the 2D / 3D application, the gravity direction does not have any relation to theta 0. Second, one cannot just use the magnetometer to read theta 0 directly. The response of magnetometer is much slower than the gyro. If the vehicle is rotating or turning too fast, it will cause problems if one just uses the magnetometer.

[0053] Figure 3A shows a system wherein relative positions can be sensed in three dimensions. One part 55 is provided with the UWB transmitter / receiver 56 communicating with the control 57. Part 58 is shown at a distinct vertical elevation relative to part 55. The control 64 on the part 58 communicates with four UWB transmitters / receivers 59, 60, 61 and 62. UWB transmitter / receiver 62 is shown in phantom to make clear that the four components 59, 60, 61 and 62 cannot all be in the same plane. By determining the relative position between the transmitter / receiver 56 and each of the transmitters / receivers 59, 60, 61 and 62 control 57 can determine the relative position between the parts 55 and 58. IMU 63 also communicates position information to control 54.

[0054] Figure 3B shows detection within a three dimensional space, but also determining pose, angle B. The part 58 is similar to that shown in Figure 3A, however, the other part 66 is now provided with two UWB transmitters / receivers 68 and 70 which communicate with the control 72. IMU 69 also communicates position information to control 72.

[0055] While the plural transmitters / receivers are shown separately, it should be understood that a single chip with plural antennas can provide plural ones of the above transmitters / receivers.

[0056] Determining relative position with UWB radio signals is generally known. However, Applicant has determined a number of unique applications which provide valuable benefits. The above UWB transmitters / receiver arrangement can be used for any of the following applications.

[0057] The controls as disclosed above, determine location using both IMU determined location and UWB determined location. This allows more accurate position determination.

[0058] In a one dimensional application one measures a position of a moving element. The distance determined by the UWB position and also by the IMU accelerators and gyros are used. By integrating the acceleration one can get the distance estimate from the IMU. By combining the IMU distance and the UWB distance one can correct each determination and make a final distance reading that is more accurate and stable. By utilizing both determined positions, several benefits are provided. First, the position determination is more accurate, and a second is that the system is more power efficient.

[0059] By using the UWB with the IMU one can make the position measurement more accurate and power efficient. This is because UWB is a RF technology, so by its nature, the RF signal is affected by the changing of surrounding environment, for example, people walking by, or tall buildings. It is also easily affected by other RF devices like Wifi, Bluetooth or even another UWB device. So, in real life, even a pair of anchors and tags keeping static and not moving, the distance reading will be noisy and jumping. The UWB technology is commonly rated with 10cm error. That means if the anchor and the tag are 100 cm away from each other and keep static, not moving, the distance reading will still jump between 90cm to 110cm.

[0060] One can apply a filter to deal with this condition. Applying a heavier filter will make the reading more stable and closer to 100cm, but will result in a slow response (the reading correspond to the tag movement lag) when the tag begins to move again.

[0061] To improve the response, one can increase the UWB sampling rate which also means increasing the power consumption and higher sampling rates is wasteful when the tag is not moving.

[0062] So, the ideal condition is where one slows down the sampling rate when the tag is static and increase the sampling rate when the tag is moving.

[0063] This will not have ideal conditions if the tag is static or moving between 90cm to 110cm with the UWB reading alone.

[0064] However, with the IMU, first we have a clear idea if the tag is moving or static with the gyro and accelerometer reading. With this information, we can dynamically adjust the sampling rate to ensure both stable reading and save power.

[0065] Second, the IMU has its own estimated IMU distance, we can put different weight for the IMU distance and UWB distance under different condition to get more accurate result.

[0066] For example, if the real distance between tag and anchor is 100cm, the IMU distance reading is 95cm, the UWB distance reading is 120cm, and we also read from the antenna that the UWB signal is weak.

[0067] Then the algorithm will know to trust the IMU distance and give it with more weight, for example 80%. So, the final distance will be 80%* IMU distance + 20%* UWB distance = 0.8*95+0.2*120 = 100cm which is coincidently the actual distance.

[0068] Another example is when the distance is far, we will assume the UWB will be less accurate and rely on the IMU distance and put more weight on it.

[0069] The IMU as utilized may be nine axis. In a nine axis IMU there are three axis accelerometers, three axis gyros, and three axis magnetometers. One dimensional applications only need six axis (three axis accelerometers and three axis gyros). 2D and 3D applications will require all nine axes.

[0070] In embodiments under this invention, the control may rely more on the IMU distance when the control and moving part are at a relatively greater distance. Thus, the IMU determined position could be given more weight relative to the UWB determined position. This will result in more accuracy. On the other hand, when the part is closer the UWB determined distance is more accurate, and provided with more weight.

[0071] There are power efficiency savings also. As an example, some components may be running on battery power and are very dependent upon power efficiency. The UWB components consume more power than the IMUs when sensing position. So when one combines the UWB and IMU determined positions, positioning can be more accurate. However, when the IMU determines that the relatively moving part is not moving or static, that means the position is not changing. The UWB can then be shut down to save power. If the IMU detects the part is again moving, then the control can restart or increase the frequency of the UWB components to get updated positions.

[0072] Figure 4 A shows an example 80 wherein there is a control 85, a UWB component 84 on a vehicle chassis 82. A moving boom 86 includes an end effector 88 that receives a UWB transmitter 90, and an IMU system 92 which both communicate with control 85.

[0073] An example is shown in Figure 4B. To determine how long the boom extends from A to B, we first have a UWB anchor installed in A and UWB Tag installed in B. One can directly measure a UWB distance result. Second, if one knows the acceleration along the AB direction, one can get a IMU distance result by integrating acceleration. However, due to gravity, the acceleration direction and amplitude read from the accelerometer is the combination of gravity and acceleration. So, one needs to know the angle theta 0 to help separate the gravity and acceleration. The gyroscope is used to get the theta 0. Now, both IMU distance result and UWB distance result are known, and they are used to correct each other fora final more accurate distance result. The IMU will be installed in both anchor A and tag B, but A is only rotating, and B rotates and moves. So, A is only used to get theta 9 to double check with the theta 9 obtained at B. They should be the same. The IMU on B will have all the IMU info to calculate IMU distance result.

[0074] Figure 5 shows yet another embodiment which is incorporated into a hard hat 102 such as worn on construction sites. Hard hat 102 is shown worn by an individual 100 near a vehicle 109 with a transmitter / receiver 110 and a control 112. In many applications, say mining applications, there are large vehicles being operated in a manner which would make it difficult to always see surrounding individuals 100. IMU 108 is also on the hard hat and communicates to control 1 12. By communicating between the transmitters / receivers 110 and 108 control 112, the control can identify an undesirably small distance. The control 112 may be programmed such as to auto stop operation of the vehicle 109 should there not be a minimum distance.

[0075] Figure 6 schematically shows a system 130 wherein the location of a first machine 132 is determined by a control 144 on a second machine 133. UWB components 136 and 134 are illustrated on machine 132, with UWB components 140 and 142 on the machine 133. An IMU 138 is positioned on the machine 132 and communicates to control 144.

[0076] A method according to this disclosure is illustrated in Figure 7. As step 120, a position of a component is determined using ultrawide band sensing.

[0077] At step 122 the position is determined using IMUs. At 123 the determined distance is considered for both 120 and 122.

[0078] At step 124 there may be further control such as to refine the determined distance based upon the two distances, and also weight one or the other based upon on the absolute distance. Moreover, the power control method as described above can also be utilized if appropriate.

[0079] In sum, this positioning system provides an interrelate control of a plurality of vehicles as described above. It can also be used for operator safety to ensure the distance away from the dangerous operating machine.

[0080] Compared with GPS RTK, which is another popular positioning technology, this is a cheaper way and can work indoor that GPS cannot.

[0081] The disclosure here provides very accurate position sensing, and allows interrelated control of a plurality of vehicles. As known, labor shortages and labor prices are becoming problematic to many industrial applications. By interrelating the operation of the systems as disclosed above, many vehicle may be operated without an operator. Moreover, by interrelating the sensing and the operation of the several components more efficient use of the machines can be realized.

Claims

CLAIMSWhat is claimed is:

1. A method comprising the steps of: providing a plurality of ultrawide band (“UWB”) components including a transmitter and / or a receiver at a first location, and including a transmitter and / or receiver at a second location, with at least one of the UWB components communicating with a control on one of said first and second locations; sending radial frequency signals from at least one of the UWB components at one of the first and second locations to a second UWB components on the other of the first and second locations, and receiving a reflective signal at the at least one UWB component, and determining an UWB relative position of the first and second locations in at least two dimensions; determining the relative position of the first and second locations utilizing an inertial motion unit (“IMU”), sending the IMU determined position to the control; and considering the ultrawide band determined relative position and the IMU determined relative position to reach a final position determination.

2. The method as set forth in claim 1, wherein said first and second locations are on a single machine with one of said locations moving relative to the other of said locations.

3. The method as set forth in claim 2, wherein a tool on the single machine moves relative to a second portion of the single machine, and the tool and the second portion provide the first and second locations.

4. The method as set forth in claim 2, wherein the relative position is in only two dimensions.

5. The method as set forth in claim 4, wherein there is also an angular relationship between the first and second locations that is determined.

6. The method as set forth in claim 2, wherein the relative position is determined in three dimensions.

7. The method as set forth in claim 6, wherein the relative position includes an angular relationship between the first and second locations.

8. The method as set forth in claim 1, wherein the locations are mounted on distinct machines, and the control is operable to coordinate operation between the two machines based upon on the determined relative position of the two locations.

9. The method as set forth in claim 8, wherein the relative position is in only two dimensions.

10. The method as set forth in claim 8, wherein there is also an angular relationship between the first and second locations that is determined.

11. The method as set forth in claim 8, wherein the relative position is determined in three dimensions.

12. The method as set forth in claim 8, wherein the relative position includes an angular relationship between the first and second locations.

13. The method as set forth in claim 8, wherein one of the machine is a device carried by a user and the other of the machines is a vehicle being controlled to approach the user’ s location.

14. The method as set forth in claim 13, wherein the device is in a hat, and communicates with the vehicle.

15. The method as set forth in claim 1, wherein the IMU includes accelerometer, magnetometers and gyros.

16. The method as set forth in claim 1 , wherein dependent on the absolute distance between the first and second location the relative weight afforded to the UWB determined relative position and the IMU determined relative position is varied.

17. The method as set forth in claim 16, wherein if the absolute distance is relatively great, then the IMU determined relative position is given more weight.

18. The method as set forth in claim 17, wherein if the relative position is relatively smaller than the UWB determined relative position is provided with more weight.

19. The method as set forth in claim 1 , wherein if the relative position of the first and second location is not changing, the UWB component is shutdown as an energy saving step.

20. The method as set forth in claim 1 , wherein the UWB signals are greater than or equal to 450 MHz.

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