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EP-4296434-B1 - IMPROVED DETERMINATION OF AN EXCAVATOR SWING BOOM ANGLE BASED ON INTERMITTENT FIRST INTERIM SWING BOOM ANGLES

EP4296434B1EP 4296434 B1EP4296434 B1EP 4296434B1EP-4296434-B1

Inventors

  • KEAN, MICHAEL GOULET
  • KAUPPINEN, Tommi Juhani

Dates

Publication Date
20260506
Application Date
20220622

Claims (14)

  1. A system for determining a swing boom angle of an excavator (1), wherein the excavator (1) comprises: • a vehicle frame (2) comprising a cabin (3), • a swing boom (4) arranged on the vehicle frame (2) and configured to be rotated relative to the vehicle frame (2) about a vertical rotation axis (5) that an actual swing boom position defines a swing boom angle, characterized in that the system comprises: • a first measuring sensor (10) configured to be mounted on: • the vehicle frame (2), or • the swing boom (4), wherein the first measuring sensor (10) is configured to determine a first interim swing boom angle of the swing boom (4) relative to the vehicle frame (2), the first interim swing boom angle being one of a discrete amount of one or more intermittent first interim swing boom angles, each of the discrete amount of one or more intermittent first interim swing boom angles being spaced from each other by at least a value of one degree, • a second measuring sensor configured to be mounted on the swing boom (4) and to determine a second interim swing boom angle of the swing boom (4) relative to the vehicle frame (2), the second interim swing boom angle being from an high-resoluted unreferenced angle range, • a processing unit configured to • receive the first interim swing boom angle and the second interim swing boom angle, and • determine the swing boom angle by applying at least one of a filter and an algorithm to the first interim swing boom angle and the second interim swing boom angle.
  2. The system according to Claim 1, wherein the system further comprises a display unit configured to be arranged in the cabin (3), wherein the display unit is connected to the processing unit, the display unit being configured to provide a visualization of swing boom angle information to the operator based on the swing boom angle.
  3. The system according to Claim 1, further comprising a counterpart intended for detection by the first measuring sensor (10), wherein the counterpart • is configured to be mounted on the swing boom (4) and to move along with the swing movement of the swing boom (4) if the first measuring sensor (10) is mounted on the vehicle frame (2), or • is configured to be mounted on the vehicle frame (2) at a known position if the first measuring sensor (10) is mounted on the swing boom (4) to move along with the swing movement of the swing boom (4).
  4. The system according to Claims 1 and 3, wherein the first measuring sensor (10) is at least one hall effect sensor (14) and the counterpart is at least one magnet (15), in particular at least one permanent magnet or at least one electro magnet.
  5. The system according to Claims 1 and 3, wherein the first measuring sensor (10) is at least one induction sensor and the counterpart is at least one metal structure.
  6. The system according to Claims 1 and 3, wherein the first measuring sensor (10) is at least one light emitting and sensing system and the counterpart is at least one reflector, in particular at least one mirror.
  7. The system according to Claims 1 and 3, wherein the first measuring sensor (10) is at least one momentary switch and the counterpart is at least one metal structure, wherein the at least one metal structure physically contacts the at least one switch and triggers the at least one switch.
  8. The system according to Claims 1 and 3, wherein the first measuring sensor (10) is at least one visual sensor configured to detect colors and the counterpart is a color gradient.
  9. The system according to Claim 1, wherein the excavator (1) comprises a pneumatic or hydraulic cylinder (12), a first end of which is coupled to the vehicle frame (2) and a second end of which is coupled to the swing boom (4), the cylinder (12) being configured to extend and to rotate the swing boom (4) based on a level of extension.
  10. The system according to Claim 1, wherein the second measuring sensor is an inertial measurement unit (IMU), wherein the IMU comprises at least one accelerometer and at least one gyroscope.
  11. The system according to one of the preceding claims, wherein the system is configured to self-calibrate based on a self-calibration procedure including the steps: • placement of the excavator (1) on a slope, wherein the slope has at least five degrees, • determination of a gravitational acceleration of the swing boom (4) relative to the slope by the accelerometer of the second measuring sensor, • extension of the cylinder (12) to a maximum or a minimum level of extension, • movement of the swing boom (4) to a first position, wherein the first position corresponds to the maximum or the minimum extension level of the cylinder (12), • determination of the swing boom angle at the first position based on the gravitational acceleration of the swing boom (4) relative to the slope, • movement of the swing boom (4) to a second position, wherein the second position corresponds to the maximum or the minimum extension level of the cylinder (12) opposed to the extension level of the cylinder (12) at the first position, • determination of the swing boom angle at the second position based on the gravitational acceleration of the swing boom (4) relative to the slope, • movement of the swing boom (4) to a third position, wherein at the third position the first measuring sensor (10) determines an intermittent first interim swing boom angle relative to the vehicle frame (2), • determination of the swing boom angle at the third position based on the gravitational acceleration of the swing boom (4) relative to the slope, • determination of a range of motion of the swing boom (4) and the position of the first measuring sensor (10) based on the determined swing boom angles at the first, the second and the third position.
  12. The system according to one of claims 1 to 10, wherein the system is configured to self-calibrate based on a self-calibration procedure including the steps: • movement of the swing boom (4) to a first position, wherein the first position corresponds to a maximum or a minimum extension level of the cylinder (12), • movement of the swing boom (4) to a second position, wherein the second position corresponds to the maximum or the minimum extension level of the cylinder (12) opposed to the extension level of the cylinder (12) at the first position, • movement of the swing boom (4) from the second position back to the first position, • recording of measurements from the first (10) and the second measuring sensors during the movement of the swing boom (4), • recording of measurement timings from the first measuring sensor (10) during the movement of the swing boom (4), • determination of a range of motion of the swing boom (4) and the position of the first measuring sensor (10) based on the recorded measurements from the second measuring sensor and the measurement timings from the first measuring sensor (10).
  13. The system according to one of the preceding claims, wherein the system further comprises a global position sensor configured to be mounted on the swing boom (4), wherein the global position sensor provides a position measurement of the swing boom (4) in a global reference frame.
  14. The system according to Claim 13, wherein Claim 13 refers back to one of claims 1 to 10, wherein the system is configured to self-calibrate based on a self-calibration procedure including the steps: • movement of the swing boom (4) to a first position, wherein the first position corresponds to a maximum or a minimum extension level of the cylinder (12), • determination of an exact first position of the swing boom (4) at the first position with the global position sensor, • movement of the swing boom (4) to a second position, wherein the second position corresponds to the maximum or the minimum extension level of the cylinder (12) opposed to the extension level of the cylinder (12) at the first position, • determination of an exact second position of the swing boom (4) at the second position with the global position sensor, • movement of the swing boom (4) to a third position, wherein at the third position the first measuring sensor (10) determines an intermittent first interim swing boom angle relative to the vehicle frame (2), • determination of an exact third position of the swing boom (4) at the third position with the global position sensor, • calculation of a rotation axis position based on the determined exact first, second and third positions expressed in a global reference frame, • calculation of a first swing boom angle defined by the first and second position, • calculation of a second swing boom angle defined by the first and third position, • calculation of a third swing boom angle defined by the third and second position, • determination of a position of at least one point on the vehicle frame (2) with the global position sensor, • conversion of the calculated first, second and third swing boom angles based on the position determinations with the global position sensor into swing boom angles relative to the vehicle frame (2), wherein the conversion is based on the calculated rotation axis position and the position of at least one point on the vehicle frame (2).

Description

FIELD OF THE INVENTION The present invention relates to a system for determining a swing boom angle of an excavator, wherein the excavator comprises a vehicle frame comprising a cabin and a swing boom arranged on the vehicle frame and configured to be rotated relative to the vehicle frame about a rotation axis that an actual swing boom position defines a swing boom angle. Such excavators are known from DK180402B1 and WO2021/028002A1 BACKGROUND OF THE INVENTION Large scale excavators are earth moving machines that consist of a lower part that rests on the ground and supports tracks or wheels to move the excavator, a rotating upper part mounted to the lower part by means of a large bearing with a vertical axis of rotation and a dig structure that is composed of several components attached to each other and the rotating upper part by means of linkage pins with horizontal axes of rotation that are parallel to each other. Miniature excavators are also capable of swinging the dig structure relative to the rotating upper part. There is a pin with a vertical rotation axis in between the dig structure and the rotating upper part. This type of construction is called a swing boom because the boom swings relative to the upper part resulting in a swing boom angle. Backhoes are earth moving machines that consist of a machine frame supported by wheels attached to a loader dig structure and an excavating dig structure. Both digging structures are composed of several components forming a serial kinematic chain ending in a digging implement. Systems exist to track the motion of these kinematic linkages. However, the excavating dig structure is attached to the vehicle frame with a joint that allows the entire dig structure to rotate about the vertical direction with respect to the vehicle frame. Typical sensing algorithms rely on integrating gyroscopes to measure displacements in position and measuring gravity with an accelerometer to stabilize the gyroscope integrations and detect the true orientation over long time frames. Over time the integration of the gyroscope measurement will drift due to uncorrected bias and sensor noise. The gravity measurement cannot be used to stabilize the swing boom rotation as the rotational axis is aligned or nearly aligned with gravity and thus the swing boom angle has no impact on how gravity is observed by the accelerometers. DK180402B1 discloses a wire sensor to measure the length of the cylinder used to actuate a swing boom movement on mini excavators with swing boom functionality. The wire sensor is a self-retracting spool of wire that has an angular encoder mounted to measure rotation of the spool relative to the housing. In this installation, the housing is mounted onto the main upper part of the excavator. The wire is extended and affixed to the swing boom structure. There is a one-to-one correspondence between the measurement of the angular encoder and the swing boom angle with respect to the upper part. US 7,650,252 B2 discloses a system and a method to sense the inclination of a machine element, such as a platform, and eliminate tangential and radial acceleration errors. The platform defines orthogonal X and Y axes, and is rotatable about a Z axis. An inclinometer, mounted on the platform at a location spaced from the axis of rotation by a distance r, provides inclinometer outputs indicating acceleration in the X and Y directions. A rate gyro on the platform senses the rotational speed of the platform. The rate gyro output is differentiated and multiplied by r to determined tangential acceleration at the inclinometer. A circuit resolves the tangential acceleration into X axis and Y axis components, which are used to correct the inclinometer outputs for errors that would otherwise result from tangential acceleration. There is a need to develop systems which determine accurately the swing boom angle of excavator without relying on integrating gyroscopes and stabilizing the gyroscope integrations by measuring gravity with an accelerometer. Further, systems are required which provide alternative approaches to track the swing boom angle and do not rely on a wire sensor. OBJECT OF THE INVENTION It is therefore an object of the invention to provide an improved system for determining a swing boom angle of an excavator. These objects are achieved by realizing at least part of the features of the independent claims. Features which further develop the invention in an alternative or advantageous manner are described in the dependent patent claims. SUMMARY OF THE INVENTION The present invention relates to a system for determining a swing boom angle of an excavator, wherein the excavator comprises a vehicle frame comprising a cabin and a swing boom arranged on the vehicle frame and configured to be rotated relative to the vehicle frame about a rotation axis that an actual swing boom position defines a swing boom angle. The system comprises a first measuring sensor configured to be mounted on the