Method for orienting an effector carrying an assembly tool relative to a surface

Abstract

A method and a device for orienting an effector relative to a surface by means of a device comprising an articulated arm, at least one tool which is designed to carry out an assembly step, at least three sensors and a controller. The method comprises the steps of determining by the controller the position of the sensors on the effector and rotating the articulated arm according to at least one dimension, so as to orient the tool carried by the effector according to an angle which is predetermined relative to the normal to the surface.

Claims

1-13. (canceled)

14. A method for orienting an effector relative to a surface by means of a device comprising an articulated arm, at least one tool which is configured to carry out an assembly step, at least three sensors and a controller, wherein the method comprises the following steps: determining, by the controller, a position and an orientation of the at least three sensors on the effector; rotating the articulated arm according to at least one dimension, so as to orient the tool carried by the effector according to an angle which is predetermined relative to the normal to the surface.

15. The method as claimed in the claim 14, wherein the at least three sensors also measure a distance between the surface and the effector.

16. The method as claimed in claim 14, wherein the rotating step is carried out simultaneously with a displacement of the effector relative to the surface.

17. The method as claimed in claim 14, wherein the step of determining the position of the sensors on the effector comprises the following steps: manually acquiring a first set of measurements carried out by each of the at least three sensors on two predetermined distinct positions of the effector, with the effector being positioned by an operator normal relative to the surface; calculating the position and the orientation of the at least three sensors from the first set of measurements.

18. The method as claimed in claim 14, wherein the step of determining the position of the sensors on the effector comprises the following steps: automatically acquiring a second set of measurements carried out by each of the at least three sensors on at least two distinct positions of the effector, with the effector carrying out at least one movement of rotation and a plurality of measurements being taken during the rotation of the effector; determining, by the controller, of the position and the orientation of the at least three sensors on the effector from the second set of measurements.

19. The method as claimed in claim 17, wherein the step of manually acquiring a first set of measurements comprises: positioning the effector on a first predetermined plane, which is perpendicular to the normal relative to the surface; measuring, for each of the at least three sensors, a predetermined physical item of data; positioning the effector on a second predetermined plane, which is perpendicular to the normal relative to the surface; measuring, for each of the at least three sensors, a predetermined physical item of data.

20. The method as claimed in claim 17, wherein the step of determination of the position of the sensors on the effector comprises the following steps: automatically acquiring a second set of measurements carried out by each of the at least three sensors on at least two distinct positions of the effector, with the effector carrying out at least one movement of rotation and a plurality of measurements being taken during the rotation of the effector; determining, by the controller, the position and the orientation of the at least three sensors on the effector from the second set of measurements, and wherein the determining the position of the at least three sensors on the effector in the step is carried out by application of a non-linear optimization algorithm from the first and second sets of measurements.

21. The method as claimed in claim 19, wherein the first predetermined plane is flush with the wall of the surface.

22. The method as claimed in claim 19, wherein a distance between the effector and the second predetermined plane is greater than a distance between the effector and the first predetermined plane.

23. The method as claimed in claim 14, wherein at least one of the at least three sensors is a laser sensor.

24. The method as claimed in claim 14, wherein at least one of the at least three sensors is an inductive sensor.

25. The method as claimed in claim 14, wherein at least one of the at least three sensors is a force sensor.

26. A device for implementation of the method as claimed in claim 14, comprising an effector comprising at least one tool which is configured to carry out an assembly step, an articulated arm, a plurality of sensors, and a controller comprising input modules and output modules, said effector being arranged on an end of the articulated arm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other particular advantages, objectives and characteristics of the invention will become apparent from the following non-limiting description of at least one particular embodiment of the method and device which are the subject of the present invention, with reference to the appended drawings in which:

[0050] FIG. 1 represents, in the form of a logic diagram, a particular embodiment of the method which is the subject of the invention, for orientation of an effector relative to a surface;

[0051] FIG. 2 represents, in the form of a diagram in cross-section, a particular embodiment of the device for implementation of the method which is the subject of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] The present description is provided on a non-limiting basis, each characteristic of an embodiment advantageously being able to be combined with any other characteristic of any other embodiment.

[0053] It should hereby be noted that the figures are not to scale.

[0054] FIG. 1 shows a method 10 for orientation of an effector 225 relative to a surface 100, by means of a device 20, illustrated in FIG. 2, comprising an articulated arm, at least one tool which is designed to carry out a step of assembly, at least three sensors 205, 210, 215 and a controller 220, which method comprises the following steps: [0055] determination 105, by the controller, of the position and the orientation of the sensors 205, 210, 215 on the effector 225; [0056] rotation 150 of the articulated arm according to at least one dimension, so as to orient the tool carried by the effector 225 according to an angle which is predetermined relative to the normal to the surface 100.

[0057] During the step 105, the position and the relative orientation of the sensors 205, 210, 215 present on the effector 225 relative to the surface 100 are determined. The step 105 makes it possible to position the effector 225, and thus the tool carried by the effector 225, according to an angle predetermined in the step 150, irrespective of the position of the sensors on the effector 225.

[0058] The step 105 comprises at least one measurement by each of the sensors 205, 210, 215 of at least one item of data representative of a physical value and a calculation, from the set of measurements acquired, of the position and the orientation of the sensors 205, 210, 215 on the effector 225.

[0059] In some embodiments, the step 105 comprises a so-called manual step 110 of acquisition of a first set of measurements. In some embodiments, the step 105 comprises a so-called automatic step 130 of acquisition of a second set of measurements. In some preferred embodiments, the step 105 comprises a so-called manual acquisition 110 and a so-called automatic acquisition 130.

[0060] The values measured can, for example, be the distance between the sensor and the surface 100, or a force applied by the surface 100 on the sensor. The value measured by the sensor is sent to the controller, which processes the information and carries out the calculation steps. In some embodiments, the connection between the sensors and the controller is sent in the form of an analog signal. In other embodiments, the signal sent by the sensors to the controller is a digital signal.

[0061] On the basis of the measurements acquired by the sensors, the controller determines the orientation of the assembly tool carried by the effector 225 relative to the surface 100. Then, the calculated orientation of the tool is compared by the controller with a predetermined target orientation necessary in order to carry out an assembly operation. The controller issues a command to the articulated arm, so that the articulated arm carries out a movement in order to orient the assembly tool according to an angle which is predetermined relative to the surface 100.

[0062] In some embodiments, which, in particular, are designed for drilling operations, the tool is positioned normal to the surface 100 in the step 150 of rotation of the articulated arm.

[0063] In some embodiments, the method according to the invention carries out a series of assembly operations in succession on a single part. In this embodiment, the so-called manual acquisition step 110 can be carried out a single time for a plurality of assembly operations. In this embodiment, the so-called automatic acquisition step 130 can be carried out before each assembly operation.

[0064] In some embodiments, the sensors 205, 210, 215 also measure the distance between the surface 100 and the effector 225.

[0065] In some embodiments, the step 150 of rotation is carried out simultaneously with a displacement of the effector 225 relative to the surface 100. This embodiment is particularly suitable for carrying out a continuous assembly operation such as welding.

[0066] In some embodiments, the step 105 of determination of the position of the sensors on the effector 225 comprises the following steps: [0067] acquisition 110 of a first set of measurements carried out by each of the sensors 205, 210, 215 on two predetermined distinct positions of the effector, with the effector being positioned by an operator normal relative to the surface 100; [0068] calculation 120 of the position and the orientation of the sensors 205, 210, 215 from the first set of measurements.

[0069] In some embodiments, the step 105 of determination of the position of the sensors on the effector 225 comprises the following steps: [0070] acquisition 130 of a second set of measurements carried out by each of the sensors 205, 210, 215 on at least two distinct positions of the effector 225, with the effector carrying out at least one movement of rotation, and a plurality of measurements being taken during the rotation of the effector; [0071] determination 140 by the controller of the position and the orientation of the sensors on the effector from the second set of measurements.

[0072] This embodiment is complementary to the step 120 of calculation of the position and of the orientation of the sensors 205, 210, 215 from the first set of measurements. The results obtained in the step 120 can be used to initialize the parameters for the purpose of a non-linear optimization carried out in the step 140.

[0073] In some embodiments, the step 110 of acquisition of a first set of measurements comprises the following steps: [0074] positioning 112 of the effector 225 on a first predetermined plane, perpendicular to the normal relative to the surface 100; [0075] measurement 114 for each of the sensors of a predetermined physical item of data; [0076] positioning 116 of the effector 225 on a second predetermined plane, perpendicular to the normal relative to the surface 100; [0077] measurement 118 for each of the sensors of a predetermined physical item of data.

[0078] In some embodiments, the determination of the position of the sensors on the effector 225 in the step 140 is carried out by application of a non-linear optimization algorithm from the first and second sets of measurements.

[0079] In some embodiments, the step 140 of non-linear optimization comprises a calculation step using a Levenberg-Marquardt algorithm

[0080] In some embodiments, the first plane is flush with the wall of the surface 100.

[0081] In some embodiments, the distance between the effector 225 and the second plane is greater than the distance between the effector 225 and the first plane.

[0082] In some embodiments, at least one sensor is a laser sensor. In the embodiments which implement a laser sensor, the physical value measured is the distance. The sensor projects a ray onto the surface 100, which in turn returns the ray of light. The sensor acquires the ray of light reflected, then, the travel time measured, or phase difference, between the emission and the reception, makes it possible to calculate the distance.

[0083] In some embodiments, at least one sensor is an inductive sensor.

[0084] Inductive sensors form part of the category of proximity sensors which are characterized by the absence of a link between the sensor and the object. The detection is thus carried out by means of a field which can be electric, magnetic or electromagnetic.

[0085] Proximity sensors exist in two modes, i.e., analog or binary. In the case of the binary mode, the signal is either high or low according to the distance. The analog mode makes it possible to have a signal which is dependent on the distance separating the sensor from the surface 100.

[0086] In some embodiments, at least one sensor is an inductive sensor with variable reluctance. Inductive sensors with variable reluctance are sensors constituted by a permanent magnet placed inside a coil. When a metal object is placed in the vicinity of the sensor, the magnetic reluctance of the circuit (capacity of the circuit to oppose the input of a magnetic field) varies, and permits the creation of a current in the coil.

[0087] In some embodiments, at least one sensor is an inductive sensor with Foucault currents. Inductive sensors with Foucault currents are sensors which produce an oscillating magnetic field at their end. When a metal object passes into this magnetic field, the latter is either attenuated or disrupted, depending on the nature of the metal. The magnetic field created at the end of the sensor is obtained from a coil subjected to a sinusoidal voltage with a low frequency of approximately a few kilohertz.

[0088] In some embodiments, at least one sensor is an inductive sensor of any other type.

[0089] In some embodiments, at least one sensor is a force sensor. The force sensor measures a force applied to an object and converts it into an electric signal.

[0090] FIG. 2 shows a particular embodiment of the device 20 for implementation of the method which is the subject of the invention, comprising an effector 225 comprising at least one tool which is designed to carry out an assembly step, an articulated arm 235, a plurality of sensors 205, 210, 215, and a controller 220 comprising input modules and output modules, the effector being added on to the end of the articulated arm 235.

[0091] The device 20 comprises at least three sensors 205, 210, 215. In some embodiments, the device 20 comprises a number of sensors which is more than three.

[0092] In some embodiments, the controller 220 of the system is complemented by a second controller (not represented) specific to the robot which carries the articulated arm 235. In this embodiment, the controller 220 of the system carries out all of the calculation steps on the basis of the data gathered by the sensors, then issues commands which it transmits in analog or digital form to the controller of the robot, which then makes the articulated arm 235 execute the movement.

[0093] In some embodiments, the signal which is emitted by at least one sensor 205, 210, 215 to the controller 220 during the acquisition of measurements is an analog signal. In some embodiments, the signal which is emitted by the controller 220 to the articulated arm 235 to order a movement is an analog signal.

[0094] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.