Method for generating a control signal for a conveyor, conveyor control method and corresponding conveyor

Abstract

The invention relates to a method for generating a signal for controlling a conveyor with at least an advancing step (E1), a reversing step (E2), and a step (E') of changing direction. The control signal comprises trajectory portions corresponding to acceleration phases (A1, A2) and secondary so-called jerk phases (j). The generation method comprises steps for establishing initial parameters, for computing a period of time (tmin) from at least one initial parameter, and for computing at least one trajectory portion according to an associated trajectory portion equation. The invention further relates to a method for controlling a conveyor according to a generated control signal, and to a conveyor intended to be controlled.

Description

Method for generating a control signal for a conveyor, method for controlling the conveyor, and corresponding conveyor

[0001] The present invention relates to the field of conveyors, particularly inertia conveyors, for moving objects or parts of varying sizes and masses towards a collection point, for example. Such conveyors can, for instance, be used in object individualization machines with vision control, enabling automated sorting. The present invention relates in particular to a method for generating a control signal and a method for controlling such a conveyor.

[0002] In many industries, such as mechanical engineering (particularly watchmaking), electronics, food processing, and construction (building and public works), objects or materials of varying sizes are produced in large quantities. These must then be packaged into batches, for example, to be sent to distribution centers or to locations where they are used in the manufacture or production of more complex parts or components. Upon leaving the production unit, these parts are generally moved to another station for further processing. One example is the conveying of granular materials or powders (for example, in the food processing or construction industries). High-precision conveying allows for the accurate dosing of these powders by weight measurement.

[0003] Depending on the type of part to be transported, and more particularly depending on its shape or constituent material, certain transport devices such as belt conveyors or vibrating rail conveyors cannot be used.

[0004] Indeed, in the case of belt conveyors, the positioning of parts during their transport is not very precise, which can be detrimental to their conformity control, for example by a vision device placed on such a belt conveyor.

[0005] Furthermore, in the case of vibrating conveyors, such as those with blades and electromagnets, the positioning of parts during transport is also imprecise, and these parts can be damaged during transport due to vibrations and impacts between the parts or with the conveyor surface. Indeed, the parts are not in continuous contact with the conveyor surface and sometimes jump or detach from it. Therefore, such conveyors are unsuitable for transporting fragile parts, for example. To improve productivity, it is necessary to develop conveyors capable of transporting both fragile and non-fragile parts while ensuring precise positioning during transport.

[0006] Inertia conveyors are known to have a transporting element on which the parts to be transported are placed and move in a parallel, horizontal direction. The transporting element has reciprocating movements, such as a back-and-forth motion, to allow the parts to slide along it. Thus, the parts remain in constant contact with the transporting element during their movement, with good accuracy regarding their direction of travel. Such inertia conveyors are therefore suitable for transporting numerous parts, including fragile ones, such as glass.

[0007] It is known in particular from conveyors comprising a mechanical drive cam whose rotation makes it possible to generate the reciprocating, back-and-forth movement of the conveying element when it cooperates with such a cam.

[0008] However, this solution presents reproducibility problems. It has been observed that, particularly for small parts, the conveyor may not function correctly, or the conveying speed may be too slow. Furthermore, unwanted vibrations have been measured in all directions during operation.

[0009] It was also observed with this solution that the gap between certain parts, even those that were externally identical, could not be constant; the parts could move closer together or, conversely, move further apart from each other over time.

[0010] Furthermore, with this mechanical solution, the trajectory of the drive cam is entirely determined by the machining parameters and cannot be adjusted or reconfigured once the conveyor is installed. Moreover, designing a rotary conveyor based on a mechanical cam system can be very complex.

[0011] Another solution has been proposed in which an actuator of the conveying element is controlled by a square wave electrical signal and accelerates discontinuously. However, these discontinuities generate unwanted vibrations, particularly during acceleration transitions, affecting the conveyor's performance.

[0012] The invention aims to overcome, at least partially, one or more of the drawbacks of the prior art by providing a controlled / piloted conveyor that advances parts in a highly repeatable and stable manner, while minimizing unwanted vibrations. Another objective is to optimize the speed of the parts transported by the conveyor.

[0013] To this end, the invention relates to a method for generating a control signal for a parts transport conveyor, said conveyor comprising: a transporting element having a transport surface on which the parts to be transported are intended to be placed, and a drive device configured to drive the transporting element in an asymmetric reciprocating motion, the asymmetric reciprocating motion having a displacement in a direction of advancement and a displacement in a direction of recoil opposite to the direction of advancement, said method being configured to generate a control signal of at least one advancement step of the drive device at an advancement speed, of at least one recoil step of the drive device at a recoil speed, and of at least one change of direction step between the advancement step and the recoil step, during the change of direction step,The forward or reverse speed of the drive device varies until it reaches a zero reversing speed, at which point the direction of forward or reverse movement of the drive device changes.

[0014] According to the invention, the control signal comprises a predefined number of trajectory segments corresponding to at least two acceleration phases with non-zero and constant respective acceleration values ​​over an associated period, and at least one secondary phase, referred to as a "jerking" phase, with a non-zero period between two acceleration phases. The jerking value is the derivative of the acceleration with respect to time and is constant for all secondary phases. At least one change of direction step is initiated during at least one secondary phase, and the change in the direction of forward or backward movement occurs during an acceleration phase, the acceleration being non-zero and constant.The method for generating the control signal includes: at least one step to establish a predefined number of initial parameters from among at least one acceleration, at least one time datum, at least one velocity, and a jolt value; at least one step for calculating at least one period from at least one of the initial parameters; and at least one step for calculating at least one portion of the trajectory of the drive device according to an associated portion-of-trajectory equation for a time interval from among the period of at least one acceleration phase and the period of at least one secondary phase, the portion-of-trajectory equation being a function of time, the forward speed, and at least one parameter from among: at least one initial parameter including at least one acceleration, the jolt value, at least one period of an acceleration phase, at least one period between two acceleration phases.

[0015] The said generation process may further include one or more of the following characteristics described below, taken separately or in combination.

[0016] The control signal defines, for example, a first acceleration phase with a first constant positive acceleration over a first period.

[0017] The control signal defines, for example, a second acceleration phase with a second constant negative acceleration over a second period.

[0018] The control signal defines, for example, a third acceleration phase with a third constant positive acceleration over a third period.

[0019] The initial parameters may include at least one, or even all, of the following accelerations: the first positive acceleration, the second negative acceleration, and the third positive acceleration.

[0020] At least one portion of the trajectory can correspond to a time interval among the first period, the second period, the third period and the period of at least one secondary phase.

[0021] The second negative acceleration may present an absolute value that is maximal relative to the acceleration values ​​reached between two stages of change of direction.

[0022] The third positive acceleration can present an absolute value which is maximum relative to the acceleration values ​​reached between two stages of change of direction.

[0023] The first period can be an initial parameter.

[0024] The initial speed of the drive device can be an initial parameter.

[0025] During the advancement stage, the drive device may exhibit a positive initial velocity which increases according to the first positive acceleration and reaches a maximum velocity.

[0026] When maximum speed is reached, the first reversal phase can begin, with a decrease in the speed of the drive device and a decreasing acceleration until it reaches the second negative acceleration. The reversing phase can then begin.

[0027] During the recoil stage, the speed of the drive device can decrease according to the second negative acceleration and reach a minimum speed.

[0028] When the minimum speed is reached, a second reversal stage can begin, with an increase in the speed of the drive device and a progressively increasing acceleration until reaching the third positive acceleration. A new forward movement stage can then begin.

[0029] At least one period of a secondary phase between two acceleration phases can be calculated from at least two accelerations and the jerk value.

[0030] The said generation process may include a step of calculating the period of the secondary phase between said first and second acceleration phases according to the following formula: with a base corresponding to the first positive acceleration, -a min corresponding to the second negative acceleration, and j corresponding to the value of the jerk.

[0031] The said generation process may include a step of calculating the period of the secondary phase between said second and third acceleration phases according to the following formula: with a max corresponding to the third positive acceleration, -a min corresponding to the second negative acceleration, and j corresponding to the value of the jerk.

[0032] The said generation process may include a step of calculating the period of the secondary phase between the said third and first acceleration phases according to the following formula: with a max corresponding to the third positive acceleration, a base corresponding to the first positive acceleration, and j corresponding to the value of the jerk.

[0033] At least the second period can be calculated from at least two of the accelerations, the jerk value, the first period, the initial speed of the drive device and the periods of the secondary phases.

[0034] At least the third period can be calculated from at least two of the accelerations, the jerk value, the first period, the initial speed of the drive device and the periods of the secondary phases.

[0035] The third period may be a function of the second period.

[0036] The second period can be greater than or equal to zero.

[0037] The third period can be greater than or equal to zero.

[0038] The third period, for example, is shorter than the second period.

[0039] The said generation process may include a step of calculating the second period according to the following formula: , with: A corresponding to a first coefficient as a function of the acceleration during said second and third acceleration phases, B corresponding to a second coefficient as a function of the acceleration during said acceleration phases, of the first period, of the initial speed of the drive device and of the period of the secondary phases between the first and second acceleration phases and between the second and third acceleration phases, and Cpr corresponding to a third coefficient as a function of the acceleration during said acceleration phases, of the initial speed of the drive device, of the first period, of the periods of the secondary phases, and of the value of the jolt during the secondary phases.

[0040] The said generation process may include a step of calculating the third period according to the following formula: , with -a min corresponding to the second negative acceleration, a maxcorresponding to the third positive acceleration, t min corresponding to the second period, and T corresponding to a fourth coefficient that is a function of the acceleration during the said acceleration phases, the first period and the periods of the secondary phases.

[0041] The said generation process may include a step of calculating the first coefficient according to the following formula: , with -a min corresponding to the second negative acceleration, and a max corresponding to the third phase of positive acceleration.

[0042] The said generation process may include a step of calculating the second coefficient according to the following formula: with a base corresponding to the first positive acceleration, -a min corresponding to the second negative acceleration, a max corresponding to the third positive acceleration, t basecorresponding to the first period, τ1 corresponding to the period of the secondary phase between the said first and second acceleration phases, τ2 corresponding to the period of the secondary phase between the said second and third acceleration phases, v0 corresponding to the initial speed of the drive device, and j corresponding to the value of the jolt.

[0043] The said generation process may include a step of calculating the third coefficient according to the following formula: with a base corresponding to the first positive acceleration, -a min corresponding to the second negative acceleration, a max corresponding to the third positive acceleration, t basecorresponding to the first period, τ1 corresponding to the period of the secondary phase between said first and second acceleration phases, τ2 corresponding to the period of the secondary phase between said second and third acceleration phases, τ3 corresponding to the period of the secondary phase between said third and first acceleration phases, v0 corresponding to the initial speed of the drive device, j corresponding to the value of the jolt, C corresponding to a fifth coefficient depending on the acceleration during said acceleration phases, the first period and the periods of the secondary phases, the initial speed of the drive device and the value of the jolt, and T corresponding to the fourth coefficient.

[0044] The said generation process may include a step of calculating the fourth coefficient according to the following formula: with a base corresponding to the first positive acceleration, -amin corresponding to the second negative acceleration, a max corresponding to the third positive acceleration, t base corresponding to the first period, τ1 corresponding to the period of the secondary phase between the said first and second acceleration phases, τ2 corresponding to the period of the secondary phase between the said second and third acceleration phases, τ3 corresponding to the period of the secondary phase between the said third and first acceleration phases.

[0045] The said generation process may include a step of calculating the fifth coefficient according to the following formula: with a base corresponding to the first positive acceleration, -a min corresponding to the second negative acceleration, a max corresponding to the third positive acceleration, t basecorresponding to the first period, τ1 corresponding to the period of the secondary phase between the said first and second acceleration phases, τ2 corresponding to the period of the secondary phase between the said second and third acceleration phases, τ3 corresponding to the period of the secondary phase between the said third and first acceleration phases, v0 corresponding to the initial speed of the drive device, j corresponding to the value of the jolt.

[0046] According to one embodiment, six trajectory portions respectively associated with the first period, the second period, the third period and the period of each secondary phase between two acceleration phases, are calculated according to six equations of respective trajectory portions.

[0047] The said generation method may include at least one step of calculating a first portion of the trajectory of the drive device, corresponding to the first acceleration phase of the first period, according to a first equation of the associated trajectory portion:(1) : ,with v base the forward speed of the drive device during the forward movement stage, a base the first positive acceleration, t base the first period, t, the time.

[0048] The said generation method may include at least one step of calculating a second portion of the trajectory of the drive device, corresponding to the secondary phase between said first and second acceleration phases of period τ1, according to a second associated trajectory portion equation:(2) : with T1 a first duration corresponding to the first period, T2 a second duration corresponding to the sum of the first period and the period of the secondary phase between the first acceleration phase and the second acceleration phase, v base the forward speed of the drive device during the forward movement stage, a base the first positive acceleration, t the time.

[0049] The said generation method may include at least one step of calculating a third portion of the trajectory of the drive device, corresponding to the second acceleration phase of the second period, according to a third associated trajectory portion equation:(3) : with T2 the second duration, T3 a third duration corresponding to the sum of the second duration and the second period, v base the forward speed of the drive device during the forward movement stage, a base the first positive acceleration, -amin the second negative acceleration, t min the second period, τ1 the period between the first acceleration phase and the second acceleration phase, j the value of the jolt, t the time.

[0050] The said generation method may include at least one calculation step of a fourth portion of the trajectory of the drive device, corresponding to the secondary phase between said second and third acceleration phases of period τ2, according to a fourth associated trajectory portion equation:(4) : with T2 the second duration, T3 the third duration, T4 a fourth duration corresponding to the sum of the third duration and the period of the secondary phase between the second acceleration phase and the third acceleration phase, v base the forward speed of the drive device during the forward movement stage, a base the first positive acceleration, -a min the second negative acceleration, tmin the second period, τ1 the period between the first acceleration phase and the second acceleration phase, j the value of the jolt, t the time.

[0051] The said generation method may include at least one step of calculating a fifth portion of the trajectory of the drive device, corresponding to the third acceleration phase of the third period, according to a fifth associated trajectory portion equation:(5) with T2, the second duration, T4 the fourth duration, T5 a fifth duration corresponding to the sum of the fourth duration and the third period, v base the forward speed of the drive device during the forward movement stage, a base the first positive acceleration, -a min the second negative acceleration, t min the second period, a maxthe third positive acceleration, τ1 the period between the first acceleration phase and the second acceleration phase, τ2 the period between the second acceleration phase and the third acceleration phase, j the value of the jerk, t the time.

[0052] The said generation method may include at least one calculation step of a sixth portion of the trajectory of the drive device, corresponding to the secondary phase between the third acceleration phase and a new first acceleration phase of period τ3, according to a sixth associated trajectory portion equation:(6) : with T2 the second duration, T5 the fifth duration, T6 a period corresponding to the sum of the periods of the three acceleration phases and the three secondary phases, v base the forward speed of the drive device during the forward movement stage, a base the first positive acceleration, -a min the second negative acceleration, tmin the second period, a max the third positive acceleration, t max the third period, τ1 the period between the first acceleration phase and the second acceleration phase, τ2 the period between the second acceleration phase and the third acceleration phase, j the value of the jerk, t the time.

[0053] The control signal of the drive device may include a fundamental frequency having at least one substantially parabolic or parabolic portion.

[0054] The control signal of the drive device may include a fundamental frequency having at least one substantially cubic or cubic portion.

[0055] According to one embodiment, the fundamental frequency has at least three substantially parabolic portions and three substantially cubic alternating portions.

[0056] The drive device can follow a trajectory defined by a curve, such that the curve has on a cycle one step of advancement and one step of retreat successive, and has at least three parabolic portions and three alternating cubic portions, the parabolic portions corresponding to a movement with constant acceleration.

[0057] These acceleration phases correspond, for example, to the parabolic portions of the trajectory curve.

[0058] Secondary phases correspond, for example, to the cubic portions of the trajectory curve.

[0059] Said generation method may include a storage step in which at least one representative parameter of the control signal is stored in a conveyor control unit.

[0060] Said generation process may include a memorization step in which the generated control signal is stored in a conveyor control unit.

[0061] The invention also relates to a method of piloting a parts transport conveyor, said conveyor comprising a transporting element having a transport surface on which the parts to be transported are intended to be placed, and a drive device configured to drive the transporting element according to an asymmetric reciprocating motion, the asymmetric reciprocating motion having a displacement in a direction of advancement and a displacement in a direction of retreat opposite to the direction of advancement.The control method is configured to control, according to a control signal generated according to a control signal generation method as defined above: at least one advancement step of the drive device at an advancement speed, at least one recoil step of the drive device at a recoil speed, and at least one change of direction step between the advancement step and the recoil step, during the change of direction step, the advancement or recoil speed of the drive device varying until reaching a zero reversing speed at which the direction of advancement or recoil of the drive device changes.

[0062] The said piloting method may further include one or more of the following characteristics described below, taken separately or in combination.

[0063] The said control process may or may not include one or more steps of the process of generating a control signal as defined previously.

[0064] The said control method may include at least one preliminary step to extract the control signal or at least one parameter of the control signal stored in a memory of a conveyor control unit.

[0065] The invention further relates to a parts transport conveyor comprising: a transporting member having a transport surface on which the parts to be transported are intended to be placed, and a driven drive device, configured to drive the transporting member according to an asymmetric reciprocating motion, the asymmetric reciprocating motion having a displacement in a direction of advancement during at least one advance stage and a displacement in a direction of retreat opposite to the direction of advancement during at least one retreat stage, the drive device being configured to be driven according to a driving method as defined above.

[0066] The conveyor, controlled or driven by a command signal generated using the signal generation method described above, offers several advantages, including compactness, high part feed speed, and minimal parasitic vibrations. In fact, it is possible to achieve a much greater acceleration amplitude than with a mechanical cam-driven conveyor, and therefore very high part feed speeds.

[0067] Other advantages and features of the invention will become clearer upon reading the following description, given by way of illustrative and non-limiting example, and the accompanying drawings, among which:

[0068] represents one embodiment of a linear conveyor.

[0069] represents one embodiment of a rotary conveyor.

[0070] schematically represents an example of the trajectory curve of the conveyor drive device of laou 2.

[0071] schematically represents an example of the curve of the evolution of the speed of the drive device of the conveyor of laou 2.

[0072] schematically represents an example of the acceleration phase curve of the conveyor drive device of laou 2.

[0073] In these figures, identical elements bear the same reference numbers.

[0074] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments can also be combined or interchanged to provide other embodiments, without departing from the scope of the invention as defined by the claims.

[0075] In the description, certain elements can be indexed, such as "first element" or "second element." In this case, it is simply indexing to differentiate and name similar but not identical elements. This indexing does not imply any priority of one element over another, and such designations can easily be interchanged without departing from the scope of this description. Nor does this indexing imply any chronological order.

[0076] The speed of an element, for example the drive device, can be positive, zero, or negative. In the case of a negative speed, the direction of movement of the drive device is reversed compared to the direction of movement with a positive speed.

[0077] With reference to figures 1 and 2, the invention is in the field of inertia conveyors 1 for transporting one or more objects, such as granules or powder, or parts 3, or any other object, of varying sizes and masses, for example towards a collection point.

[0078] The parts 3 have a bearing surface designed to be in contact with the inertial conveyor 1. This bearing surface may be flat or nearly flat to ensure the stability of the part 3 on the inertial conveyor 1. The bearing surface may also be reduced to a line or even two points. The parts 3 may, among other things, have a general cylindrical or semi-cylindrical shape, such as vials, a general parallelepiped shape, or more complex shapes such as washers, seals, screws, and bolts.

[0079] Parts transport conveyor

[0080] In general, the inertia conveyor 1 is configured to transport the parts 3 in a direction of travel represented by the arrow F1.

[0081] In the example shown, conveyor 1 is linear. In this case, conveyor 1 transports parts 3 in a linear direction. In other words, parts 3 can be transported along a linear path.

[0082] Alternatively, in the example shown, conveyor 1 is rotary. In this case, it allows parts 3 to be transported in a direction of rotation. Parts 3 can then be transported along a trajectory that is at least partially circular or helical, with a radius and pitch that can be fixed or variable.

[0083] In order to transport the parts 3, the conveyor 1 includes a transport element 5 such as a platform, and a drive device 7 for this transport element 5.

[0084] The shape of the conveying element 5, such as a platform, can be adapted according to the type of conveyor 1. In the example of the, the platform defines a parallelepiped shape, while in the example of the, the platform has a disc shape. The direction of travel represented by arrow F1 is, for example, parallel to the long side of the parallelepiped shape of the platform () or, alternatively, rotating around the center of the disc ().

[0085] Regardless of the embodiment of the conveyor 1 in Figures 1 and 2, the transporting element 5 has a transport surface 51 on which the parts 3 to be transported are intended to be placed. By way of non-limiting example, the transport surface 51 may be made of a material having a coefficient of kinetic friction less than 0.20, and preferably between 0.08 and 0.15.

[0086] The drive device 7 allows the transport organ 5 to be driven according to an asymmetrical reciprocating movement, as represented by the double arrow F2.

[0087] The asymmetrical reciprocating motion can occur in a plane defined by a part 10 of a motor such as a servomotor 9, described hereafter with reference to the figure, the part 10 being translationally movable. In one alternative, the asymmetrical reciprocating motion can occur in a plane perpendicular or substantially perpendicular to a drive shaft 91 of a motor such as a rotary servomotor 9, described hereafter with reference to the figure. Alternatively, or in addition, the asymmetrical reciprocating motion can occur in a plane defined by the transport surface 51 when the latter is flat.

[0088] Referring also to the diagram, this is a back-and-forth movement with at least one forward step E1 and at least one backward step E2. During the forward step E1, the transport element 5 is moved in the direction of forward movement, corresponding to the direction of arrow F1 (Figures 1 and 2). During the backward step E2, the transport element 5 is moved in a backward direction opposite to the direction of forward movement.

[0089] The drive device 7 is configured to be controlled / piloted according to a control signal generated by a control signal generation process described later.

[0090] This is a training device 7 for which at least some parameters, allowing a trajectory curve to be obtained as a function of time, can be calculated as described below.

[0091] The asymmetrical movement of the drive device 7 can overcome static friction forces between the transport surface 51 and the mounting surface of the parts 3 to be transported, so that the parts 3 slide on the transporting member 5.

[0092] The asymmetrical movement of the drive device 7 follows an acceleration profile detailed later.

[0093] The drive device 7 can be a servo device. It may include, in particular, a motor, specifically a servomotor 9.

[0094] For example, servomotor 9 comprises a motor and control electronics. The control electronics include at least one drive, specifically a digital drive (not shown), and a software controller or PLC (not shown). The drive is configured to power and regulate the motor based on the positions received from the software controller or PLC.

[0095] The transport element 5 is fixed to the servomotor 9 and will follow the latter's movements. This can be a rigid mechanical fixing, for example by screwing.

[0096] According to the first embodiment shown schematically in the figure, with a linear conveyor 1, the drive device 7 comprises a linearly moving servomotor 9. In this case, the servomotor 9 can move along a translational direction.

[0097] The servomotor 9 includes, in particular, a moving part 10 and a fixed part. In a specific, non-limiting example, the fixed part may be a magnetic track 11. The magnetic track 11 defines, for example, a channel with two rows of magnets arranged on either side of the moving part 10 of the servomotor 9, parallel to the direction of translation. The servomotor 9, for example the moving part 10, includes windings, more precisely three windings, which generate a magnetic field when electrically energized. The magnets forming the magnetic track 11 can then interact with this magnetic field, so that the moving part 10 of the servomotor 9 can move.

[0098] Alternatively, the magnetic track can form the moving part intended to cooperate with the fixed windings.

[0099] Advantageously, the drive device 7 includes a guide system not shown, such as a system of rail slides, for holding the servomotor 9.

[0100] According to the second embodiment shown schematically on the diagram, with a rotating conveyor 1, the drive device 7 includes a rotaryly moving servomotor 9.

[0101] In this example, the rotary servomotor 9 has a drive shaft 91, and the magnets forming the magnetic track 11 can be carried by this drive shaft 91. The servomotor 9 also has windings 93 wound around the drive shaft 91 that carry the magnets. In this case, the windings 93 are fixed, and it is the magnets that are moved. Alternatively, the magnetic track could form the fixed part intended to cooperate with the moving windings in a manner similar to the example described above.

[0102] In either embodiment, the servomotor windings 9 are connected to the drive. The controller or software PLC communicates to the drive the successive positions that the motor must reach over time. For example, a new position is sent every millisecond.

[0103] As an alternative or in addition, it is possible to consider that the drive device 7 includes at least one piezoelectric element.

[0104] Furthermore, the conveyor 1 may include at least one side edge (not shown). It may be fixed to one side of the conveying element 5. It may be positioned perpendicular to the conveying surface 51.

[0105] According to a specific implementation example not shown, conveyor 1 may include an image acquisition system to take at least one image of each individual part 3 as it moves within a predefined measurement zone. An optical detector may be arranged to detect the arrival of a part 3 in the measurement zone in order to trigger image acquisition. An image processing system may be provided to process the images taken by the image acquisition system in order to determine, for example, whether the parts 3 conform or not, so that any non-conforming parts 3 can be removed.

[0106] piloting method

[0107] With reference to figures 1 to 3c, generally, in operation of conveyor 1, parts 3 are placed on the conveying member 5, and the drive device 7, more specifically the motor, is driven to drive the conveying member 5 according to the asymmetrical movement (arrow F2) with a successive forward step E1 and a recoil step E2.

[0108] To do this, the piloting process can pilot or control the conveyor 1 according to at least one control signal to control the advance, the retreat, the change of direction of the drive device 7.

[0109] The control signal can be generated by a process for generating at least one control signal, detailed later. The control signal comprises a predefined number of trajectory segments associated with trajectory segment equations (explained later). These trajectory segments correspond, in particular, to at least two acceleration phases, for example, three acceleration phases A1, A2, A3, and to at least one secondary phase, called a jerk phase, with a non-zero period τ1, τ2, τ3, between two acceleration phases A1, A2, or A2, A3, or A3, A1. The control signal also includes the trajectory segment equation(s).

[0110] The steps of such a process for generating a control signal (or several control signals) can be implemented during the control of conveyor 1.

[0111] Alternatively, the steps of the process for generating a control signal (or several control signals) can be implemented in advance, separately from the control process. In the latter case, the control signal, and / or one or more parameters representing the control signal, such as equations, can be stored in a memory of a control unit (not shown) of conveyor 1. The control process may include a preliminary step to access the memory and extract or read the control signal or one or more parameters representing the control signal, such as equations.

[0112] The method of controlling conveyor 1, according to the control signal generated during the control process or in advance and extracted for control, comprises the following steps.

[0113] Progress stage

[0114] Overall, during the advancement step E1, the drive device 7 exhibits an advancement speed v base which is positive and non-zero. The forward speed of the drive device 7 is greater than or equal to the speed of the parts 3.

[0115] More specifically, when the advancement step E1 is initiated, the drive device 7 has an initial positive velocity v0. The drive device 7 then evolves with the advancement velocity v base which increases () according to a first positive acceleration a base () in particular up to reaching a maximum speed v max It should be noted that the speed of advancement v base the training device 7 continues to increase even at the end of period t base presenting a first positive acceleration a base , as long as the acceleration is positive, which occurs approximately in the middle of the period t1 (see figures 3b, 3c).

[0116] The drive device 7 moves the transport organ 5 forward relatively "slowly". The drive device 7 accelerates only slightly. This is a first positive acceleration. base which is weak.

[0117] This corresponds to a first acceleration phase A1 exhibiting the first positive acceleration a base over a first period t base The first acceleration phase A1 corresponds to an adhesion phase of part 3 or parts 3 on conveyor 1. The part or each part 3 grips by friction on the transport surface 51 and is driven by the latter so that it advances along the arrow F1 during the advancement step E1.

[0118] First step in changing direction between forward and backward

[0119] When the drive device 7 reaches maximum speed v max, a first step of change of direction E' can begin, before the drive device 7 moves backward.

[0120] During this first change of direction stage E', the speed of the drive device 7 decreases according to an acceleration that diminishes until it reaches a second negative acceleration -a min It should be noted that the variation in acceleration (which decreases or increases depending on the change of direction) is therefore progressive and continuous, which also ensures the continuous nature over time of the control of the drive device.

[0121] When the decreasing speed of the drive device 7 reaches zero reversing speed, the acceleration of the drive device 7 corresponds to this second negative acceleration -a min which is not zero. The change of direction therefore occurs during the second acceleration phase A2, at acceleration -a minThe speed is non-zero and constant. The time interval during which the reversing speed is zero tends towards zero because the acceleration at that moment is not zero. In other words, at the reversing position with a reversing speed of zero, there is no stop. The advantage of the absence of a stop is the continuity of movement and the fact that there is no generation of extraneous noise that disrupts the transport of parts and impairs productivity. The inventors have found that a productivity gain of around 100%, or even up to 300% in some cases, can be achieved compared to known prior art conveyors.

[0122] Step back

[0123] The reversing stage E2 begins when the speed of the drive device 7 reaches the reversing speed which is zero.

[0124] During the recoil stage E2, the drive device 7 moves backward very rapidly. Meanwhile, the parts 3 lose traction and are carried in the direction of travel (arrow F1) by their inertia, thus continuing to move forward along arrow F1 (Figures 1, 2). The speed of the drive device 7 is negative and decreases according to the second negative acceleration -a min (figures 3b, 3c) and this speed of the drive device 7 reaches a minimum speed v min .

[0125] The second negative acceleration -a min can, in particular, be sufficiently large to overcome the static friction forces between the transport surface 51 and the mounting surface of the parts 3 to be transported, so that the parts 3 remain in contact with the transporting element 5 and slide on it. This negative acceleration -a min is constant over a second period t minThis corresponds to a second acceleration phase A2.

[0126] The acceleration of the drive device 7 presents, on the second period t min , an absolute value |a min | greater than or equal to the absolute value of the first positive acceleration |a base | during the first acceleration phase A1.

[0127] The second negative acceleration -a min must be of the highest possible absolute value so that the time during which the absolute value of the acceleration is greater than the adhesion threshold of the part with the support is as short as possible.

[0128] This absolute value |a min | is maximal, relative to the acceleration values ​​reached between two direction change steps E', E''. These include the acceleration values ​​reached between the instant when the speed of the drive device 7 reaches the maximum speed v maxtriggering the first change of direction step E' and the instant when the speed of the drive device 7 reaches the minimum speed v min triggering a second direction change step E'', as described below.

[0129] Second stage of changing direction between retreat and advancement

[0130] When the drive device 7 reaches the minimum speed (negative speed), a second change of direction step E'' can begin, before the drive device 7 moves forward again.

[0131] During this second change of direction stage E'', the drive device 7 accelerates again . The speed of the drive device 7 increases according to an acceleration that grows until it reaches a third positive acceleration a max. Here too, we note a continuous and progressive acceleration variation so as not to induce noise or disturbances that impair the efficiency of the drive device 7.

[0132] This third positive acceleration has max is constant over a third period t max This corresponds to a third acceleration phase A3.

[0133] When the increasing speed of the drive device 7 reaches zero reversing speed, the acceleration of the drive device 7 corresponds to this third positive acceleration a max which is non-zero. The change of direction therefore occurs during the third acceleration phase A3, at acceleration a maxnon-zero and constant. As mentioned previously, the time interval during which the reversing velocity is zero tends towards zero because the acceleration at that moment is not zero. In other words, at the reversing position with a reversing velocity of zero, there is no stop.

[0134] The acceleration of the drive device 7 presents, on the third period t max , an absolute value |a max | greater than or equal to the absolute value of the first positive acceleration |a base | during the first acceleration phase A1.

[0135] This absolute value |a max| is maximum relative to the acceleration values ​​reached between two direction change steps. This includes the acceleration values ​​reached between the instant when the speed of the drive device 7 reaches the minimum speed triggering the second direction change step and an instant when the speed of the drive device 7 reaches the maximum speed triggering a new first direction change step.

[0136] A new advancement stage E1 can begin when the speed of the drive device 7 reaches the zero reversing speed.

[0137] Secondary phases

[0138] The secondary phases known as jerk phases allow a link between the different acceleration phases A1, A2, A3, they ensure a continuity of the acceleration profile.

[0139] In particular, according to the embodiment described with reference to figures 3a to 3c, three acceleration phases A1, A2, A3 and three secondary jerk phases can alternate over a cycle.

[0140] The secondary jerk phases between two acceleration phases A1, A2, A3 have non-zero durations or periods τ1, τ2, τ3. The jerk value j is the derivative of the acceleration with respect to time. This jerk value j is constant for all secondary jerk phases.

[0141] The method for generating at least one control signal is described below.

[0142] Method for generating at least one control signal

[0143] As previously stated, the control signal includes a predefined number of trajectory portions associated with trajectory portion equations (explained later), the trajectory portions corresponding in particular to at least two acceleration phases, for example three acceleration phases A1, A2, A3, and to at least one secondary phase called a jerk with a non-zero period τ1, τ2, τ3 between two acceleration phases A1, A2, or A2, A3 or A3, A1.

[0144] The trajectory of the drive device 7 is defined by a trajectory curve C0, an example of which is shown schematically on the.

[0145] The trajectory can be calculated in advance (relative to the piloting process) and with precise characteristics. The motion profile is calculated analytically, as detailed below, in order to obtain the trajectory curve C0.

[0146] Curve C0 defines the evolution of positions P (for example, in millimeters or centimeters) of the drive device 7 over time t (for example, in seconds). On the graph, the scales for positions P and time t are given for illustrative purposes only and are not exhaustive.

[0147] The control signal may include a fundamental frequency having at least one substantially parabolic or parabolic portion or similar to a parabola, corresponding to a first portion C1 of the curve C0.

[0148] Alternatively or in addition, the control signal may include a fundamental frequency having at least one substantially cubic or cubic portion or similar to a cubic curve, corresponding to a second portion C2 of the curve C0.

[0149] According to a particular example, at least three parabolic or substantially parabolic portions and three alternating cubic or substantially cubic portions may be provided.

[0150] The control signal may occasionally deviate from a purely parabolic and / or cubic control.

[0151] Of course, a control signal with higher frequencies, including additional harmonic components of the fifth order and above, is conceivable. This will have no impact on the movement because the high frequencies will be filtered by the winding in the case of an electric motor, and by mechanical inertia in all cases. It should be noted that any harmonic components of the second, third, or fourth order, if their amplitude is low compared to the fundamental frequency, have little or no impact on the performance of conveyor 1. Similarly, an anharmonic component, meaning one of any frequency, may have no significant effect if its amplitude remains low.

[0152] In particular, referring to Figures 1 to 3b, one or more control signals are generated for at least one advancement step E1 of the drive device 7 at an advancement speed v base(positive speed), of at least one reverse step E2 of the drive device 7 at a reverse speed (negative speed), and of at least one change of direction step E' or E'', between the advance step E1 and the reverse step E2.

[0153] The acceleration phases A1, A2, A3 have different acceleration values. Each acceleration phase A1, A2, A3 has a specific acceleration value. base , -has min , has max respective which is constant over an associated period t base , t min , t max .

[0154] The first portions C1 of the curve C0 correspond to the acceleration phases A1, A2, A3, and therefore to a motion with constant acceleration. The second portions C2 of the curve C0 correspond to the secondary phases known as jerk phases.

[0155] The secondary jerk phases allow the C0 curve to be smoothed. The trajectory, defined by this C0 curve, is obtained by integrating twice the acceleration and jerk values ​​j, examples of which are given later.

[0156] Lamontre shows a curve representing the evolution of the speed V (for example, in millimeters per second) of the drive device 7 over time t (for example, in seconds). On the graph, the speed V and time t scales are given for illustrative purposes only and are not exhaustive.

[0157] During the direction change step E' or E'', the forward or reverse speed of the drive device 7 varies, passing through a zero reversing speed at which the direction of forward or reverse movement of the drive device 7 changes. When the zero reversing speed is reached, the drive device 7 exhibits an acceleration -a min , has max non-zero and constant over a period tmin , t max predefined. This acceleration -a min , has max presents a maximum absolute value over the period t min , t max predefined, relative to the acceleration values ​​reached between two change of direction steps E' and E''.

[0158] Lamontre shows a curve representing the evolution of the acceleration a (for example, in units of acceleration g) of the drive device 7 over time t (for example, in seconds). On the graph, the scales for acceleration a and time t are given for illustrative purposes only and are not exhaustive.

[0159] The definition of the trajectory (C0 curve of the) can be obtained from the acceleration curve ().

[0160] It is important to understand that when the drive device 7 has a speed, an acceleration is applied to reverse the speed and also the direction of movement of the drive device 7.

[0161] In the case of a positive velocity, the applied acceleration will first decrease the speed of movement until it passes through zero (reversal velocity), and it is at this point that the direction of movement changes. At this moment, the acceleration is non-zero (here, negative).

[0162] In the case of a negative velocity, the applied acceleration will initially increase the speed of movement, passing through zero (reversal velocity), and it is at this point that the direction of movement changes. At this moment, the acceleration is non-zero (here, positive).

[0163] Examples of equations for portions of the trajectory

[0164] The process of generating the control signal includes one or more steps to calculate the trajectory of the drive device 7 corresponding to the curve C0 of the.

[0165] The trajectory of the drive device 7 is periodic with a period of T6. The equation of the trajectory x(t) of the drive device 7 over time t can be defined in parts over the period T6. The period T6 corresponds to a cycle comprising the first A1, second A2, and third A3 acceleration phases, and the secondary alternating jerk (or jerk) phases. .

[0166] The trajectory of the drive device 7 over time t can be defined as a recurrence of the trajectory equation over the period T6. In other words, the trajectory equation can be calculated over this period T6 and then looped, the point at time zero t = 0 corresponding to the point at time t = T6.

[0167] Alternatively, at the end of period T6, instead of looping along the same trajectory, another trajectory can be calculated from another set of parameters.

[0168] During one or more sub-steps of the calculation, the periods t base , t min , t max The acceleration phases A1, A2, A3, and the periods τ1, τ2, τ3, as well as the secondary jerk phases, can be calculated. These are the periods associated with each portion C1, C2 of the trajectory (for example, the cubic and parabolic portions of the curve C0).

[0169] The trajectory (curve C0) can be based on one or more initial parameters or reference parameters, including at least one acceleration a base , -has min , has max , at least one time datum, at least one velocity, and the value of jerk or j,

[0170] Preferably, six initial parameters are defined: the three accelerations a base , -has min , has max , at least one time datum, such as the first period t baseof the first acceleration phase A1, at least one speed, such as the initial speed v0 of the drive device 7, and the value of jerk j.

[0171] One or more of these initial parameters can then be used to calculate periods t min , t max , τ1, τ2, τ3.

[0172] The method for generating the control signal therefore includes at least one step to establish or define the initial parameter(s). At least some of these initial parameters can be freely chosen and established empirically.

[0173] This can be one or more parameters, including: the first acceleration has base positive during the first acceleration phase A1, the second acceleration -a min negative during the second acceleration phase A2, the third acceleration a max positive during the third acceleration phase A3, the first period t baseof the first acceleration phase A1, the initial velocity v0 of the drive device 7, and the value of jerk j, or jerk value, that is to say the derivative of the acceleration with respect to time during the secondary phases.

[0174] We can choose one or more of these initial parameters, for example these six initial parameters, depending on the parts 3 which must move forward, be transported by the conveyor 1, in particular depending on their material, and / or their coefficient of friction, and / or their stability in motion.

[0175] It is important that the acceleration values ​​have base , -has min and a maxand jerk j, chosen for trajectory calculation, must be physically attainable by the motor, otherwise the trajectory will not be followed correctly and the parts 3 will not be transported optimally. One constraint is to ensure a continuous trajectory without outliers.

[0176] The first positive acceleration has base During the first positive acceleration phase A1, or adhesion phase, the speed is chosen according to a compromise. It must be high enough to optimize the speed reached by the transported part 3, but not so high as to prevent the part 3 from being insufficiently driven by the transporting element 5 during the forward movement step E1. This acceleration has baseis chosen to maximize the driving effect, the adhesion of the part(s) 3 to the transporting element 5. In other words, a limiting acceleration, beyond which there is no longer any adhesion and part 3 disengages, can possibly be determined, and the acceleration has base for example, it can be chosen to be lower than such a limiting acceleration.

[0177] As an illustrative and non-limiting example, the first positive acceleration has base During the first acceleration phase, A1 can be less than or equal to 0.5 g, corresponding in SI units to 4.905 ms -2 Of course, the invention is not limited to this example.

[0178] The first period t base can be chosen taking into account the effective possible stroke of the conveying element 5, which may, for example, be on the order of a few centimeters, so as not to exceed mechanical stops. The first period t baseThe duration of the first positive acceleration phase A1 can, for example, be on the order of 20 ms to 100 ms. Of course, the invention is not limited to this example.

[0179] As a non-limiting example, the second negative acceleration -a min It could be in the range of 3g to 5g, or in SI units, approximately 29.43 ms -2 at 49.05 ms -2 Of course, the invention is not limited to this example.

[0180] As a non-limiting example, the third positive acceleration has max It could be in the range of 3g to 5g, or in SI units, approximately 29.43 ms -2 at 49.05 ms -2 Of course, the invention is not limited to this example.

[0181] The initial speed v0 of the drive device 7 can, for example, be less than or on the order of 300ms -1 .

[0182] The value of jerk j is defined taking into account that conveyor 1 cannot go from a negative acceleration value to a positive acceleration value instantaneously; two too different acceleration values ​​cannot follow one another.

[0183] The jerk value j must be chosen sufficiently high to ensure a link between the acceleration values ​​of the different acceleration phases A1, A2, and A3, and to allow these chosen accelerations to be reached. The second portions C2 of the curve C0 connect the first portions C1. The higher the jerk value j, the less important the secondary phases become.

[0184] As a non-limiting example, the value of jerk j, or the derivative of the acceleration with respect to time during the secondary phases, can, for example, be around 10 million mm.s -3 Of course, the invention is not limited to this example.

[0185] The process for generating the control signal includes one or more steps for calculating other parameters or characteristics of the trajectory of the drive device 7, particularly based on the established initial parameters. Of course, the calculation can be applied to initial parameters with different values, for example, much larger ones, than the purely illustrative examples given.

[0186] In particular, once the first period t base fixed, the periods t min , t max The other two acceleration phases A2, A3 can be calculated more precisely from the equations developed subsequently.

[0187] Similarly, once the acceleration values ​​have base , -has min and a max Once the acceleration phases A1, A2, A3 and jerk j are determined, the periods τ1, τ2, τ3 of the secondary phases j can be calculated more precisely from the equations developed subsequently.

[0188] At least one period τ1, τ2, τ3 of a secondary phase can be calculated from at least two of the accelerations a base , -has min , has max and the jerk value or j-value.

[0189] The period τ1 of the secondary phase between the first acceleration phase A1 and the second acceleration phase A2 can be determined from the first positive acceleration a base during the first acceleration phase A1, of the second negative acceleration -a min during the second acceleration phase A2, and the value of jerk j corresponding to the derivative of the acceleration with respect to time during the secondary phases. The period τ1 is, for example, calculated according to the following formula:

[0190] The period τ2 of the secondary phase between the second acceleration phase A2 and the third acceleration phase A3 can be determined from the second negative acceleration -a min during the second acceleration phase A2 and the third positive acceleration a max during the third acceleration phase A3, and the value of jerk j corresponding to the derivative of the acceleration with respect to time during the secondary phases. The period τ2 is, for example, calculated according to the following formula:

[0191] The period τ3 of the secondary phase between the third acceleration phase A3 and the first acceleration phase A1 can be determined from the first positive acceleration a base during the first acceleration phase A1, of the third positive acceleration a maxduring the third acceleration phase A3, and the value of jerk j corresponding to the derivative of the acceleration with respect to time during the secondary phases. It is calculated, for example, according to the following formula:

[0192] Furthermore, at least one period t min , t max of an acceleration phase A2, A3 can be calculated from at least two of the accelerations a base , -has min , has max , the value of jerk or j, of the first period t base , the initial speed v0 of the drive device 7 and the periods τ1, τ2, τ3 of the secondary phases, in particular calculated as explained above.

[0193] The second period t min The second acceleration phase A2 can be calculated using the following formula: .

[0194] In this formula, A corresponds to a first coefficient, B corresponds to a second coefficient, and C prcorresponds to a third coefficient. These coefficients A, B, Cpr, are intermediate calculations allowing to simplify and lighten the writing of one or more of the formulas, without real physical meaning.

[0195] The first coefficient A is a function of the second acceleration -a min , negative, during the second acceleration phase A2 and the third positive acceleration a max during the third acceleration phase A3.

[0196] The first coefficient A can be calculated using the following formula: .

[0197] The second coefficient B, on the other hand, is a function of the first positive acceleration a base , of the second negative acceleration -a min , of the third positive acceleration a max , of the first period t baseof the first acceleration phase A1, of the initial velocity v0 of the drive device 7, of the period τ1 of the secondary phase between the first acceleration phase A1 and the second acceleration phase A2, of the period τ2 of the secondary phase between the second acceleration phase A2 and the third acceleration phase A3, and of the value of jerk j corresponding to the derivative of the acceleration with respect to time during the secondary phases.

[0198] The second coefficient B can be calculated using the following formula: .

[0199] Regarding the third coefficient C pr , it is a function of the first positive acceleration a base , of the second negative acceleration -a min , of the third positive acceleration a max , of the first period t base, periods τ1, τ2, τ3 of the secondary phases between the acceleration phases A1, A2, A3, of the initial velocity v0 of the drive device 7, and of the value of jerk j corresponding to the derivative of the acceleration with respect to time during the secondary phases.

[0200] The third coefficient C pr can be calculated using the following formula: .

[0201] In this formula for calculating the third coefficient C pr , T corresponds to a fourth coefficient and C corresponds to a fifth coefficient.

[0202] The fifth coefficient C is a function of the accelerations a base , -has min , has max during the three acceleration phases A1, A2, A3, of the first period t baseand periods τ1, τ2, τ3 of the secondary phases, of the initial velocity v0 of the drive device and of the value of jerk j corresponding to the derivative of the acceleration with respect to time during the secondary phases.

[0203] The fifth coefficient C can be calculated using the following formula: .

[0204] The fourth coefficient T is a function of the accelerations a base , -has min , has max during the three acceleration phases A1, A2, A3, of the first period t base and periods τ1, τ2, τ3 of the secondary phases. It can be calculated using the following formula: .

[0205] Furthermore, the third period t max can also be a function of the second period t min .

[0206] The third period t max, that is, the period of the third acceleration phase A3, can be determined from the second negative acceleration -a min , of the third positive acceleration a max , of the second period t min and the fourth coefficient T. The third period t max is calculated, for example, according to the following formula: .

[0207] The third period t max is generally less than the second period t min .

[0208] In particular, the values ​​of the second period t min and of the third period t max must be zero or positive. Otherwise, the parameter set would not allow a solution to be obtained.

[0209] The time values ​​ / periods t base , t min , t maxassociated with the acceleration phases A1, A2, A3, and τ1, τ2, τ3 associated with the secondary phases j, defined as developed previously, are unique for a given set of parameters.

[0210] Once the acceleration values ​​have base , -has min and a max and jerk j defined on a cycle, as well as the periods t base , t min , t max When associated, the trajectory can be constructed through successive integrations.

[0211] A first integration allows us to obtain the speed of the drive device 7, more precisely of the motor, and a second integration allows us to obtain the position P of the drive device 7, more precisely of the motor, during time t.

[0212] The calculation steps can be automated and performed very quickly. For example, it can take less than a second starting from the six initial parameters described above.

[0213] Over the period T6, the trajectory equation can consist of a predefined number of trajectory segment equations for respective time intervals: t base , τ1, t min , τ 2, t max , τ 3. To achieve this, the control signal generation process includes at least one calculation step for at least one or each portion of the trajectory of the drive device 7 according to an associated trajectory portion equation. Each trajectory portion corresponds to a respective time interval. The time interval can be the period t base , t min , t max of at least one acceleration phase A1, A2, A3 or the period τ1, τ2, τ3 of at least one secondary phase,

[0214] In particular, six portions of the trajectory respectively associated with the first period t base , the second period t min , the third period t maxand the period τ1, τ2, τ3 of each secondary phase, are calculated according to six equations of respective trajectory portions.

[0215] The equations for sections of the trajectory are a function of time t and the speed of advance v base , and at least one acceleration a base , -has min , has max One or more of the trajectory segment equations may also be a function of at least one parameter among: at least one period t base , t min , t max of an acceleration phase A1, A2, A3, the value of jerk j, at least one period τ1, τ2, τ3 between two acceleration phases A1, A2, A3.

[0216] To simplify the writing of the equations for the trajectory segments, the durations T1, T2, T3, T4, T5 are introduced. These durations begin at time zero t=0.

[0217] A first duration T1 corresponds to the first period t baseduring the first acceleration phase A1, i.e.: .

[0218] A second duration T2 corresponds to: the first period t base added to the period τ1 of the secondary phase between the first acceleration phase A1 and the second acceleration phase A2, i.e.: .

[0219] A third duration T3 corresponds to the sum of: the first period t base , the period τ1 of the secondary phase between the first acceleration phase A1, and the second acceleration phase A2 and the second period t min during the second acceleration phase A2, i.e.: .

[0220] A fourth duration T4 corresponds to the sum of: the first period t base ,the period τ1 of the secondary phase between the first acceleration phase A1 and the second acceleration phase A2, the second period t min, and the period τ2 of the secondary phase between the second acceleration phase A2 and the third acceleration phase A3, i.e.: .

[0221] A fifth duration T5 corresponds to the sum: the first period t base ,the period τ1 of the secondary phase between the first acceleration phase A1 and the second acceleration phase A2, the second period t min , the period τ2 of the secondary phase between the second acceleration phase A2 and the third acceleration phase A3, and the third period t max of the third acceleration phase A3, namely: .

[0222] As previously explained, the period T6 of the trajectory corresponds to the sum of the periods of the three acceleration phases A1, A2, A3 and the three secondary phases, .

[0223] A first equation (1) of a portion of the trajectory can be predicted for the first acceleration phase A1, that is, for the first period t base (or first duration T1), i.e. for Or .

[0224] The first equation (1) can be a function of the rate of advancement v base of the drive device 7 during the advancement stage E1, from the first positive acceleration to base , as well as time t.

[0225] This first equation (1) is:

[0226] (1): .

[0227] This first equation (1) corresponds to a first portion C1 of the curve C0 of the trajectory during the first acceleration phase A1.

[0228] A second equation (2) of a portion of the trajectory can be predicted for the secondary phase between the first acceleration phase A1 and the second acceleration phase A2, that is, for the period τ1, or the time interval from the end of the first duration T1 to the end of the second duration T2, i.e., for , Or .

[0229] The second equation (2) can be a function of the rate of advancement v base of the drive device 7 during the advancement stage E1, from the first positive acceleration to base , as well as the time t and the first duration T1 or first period t base .

[0230] The second equation (2) can also be a function of the result of the first equation (1) for t = T1, i.e. x(T1).

[0231] This second equation (2) is:

[0232] (2):

[0233]

[0234] This second equation (2) corresponds to a second portion C2 of the curve C0 of the trajectory during the secondary phase of period τ1.

[0235] A third equation (3) of a portion of the trajectory can be predicted for the second acceleration phase A2, that is, for the second period t min , or the time interval from the end of the second duration T2 to the end of the third duration T3, i.e. for .

[0236] The third equation (3) can be a function of the rate of advancement v base of the drive device 7 during the advancement stage E1, from the first positive acceleration to base , of the second negative acceleration -a min and of the second period t min , as well as the time t, the value of jerk j, the period τ1 between the first acceleration phase A1 and the second acceleration phase A2, and the second duration T2.

[0237] The third equation (3) can also be a function of the result of the second equation (2) for t = T2, i.e. x(T2).

[0238] This third equation (3) of a portion of the trajectory is:

[0239] (3):

[0240] This third equation (3) corresponds to a first portion C1 of the curve C0 of the trajectory during the second acceleration phase A2.

[0241] A fourth equation (4) of a portion of the trajectory can be predicted for the secondary phase between the second acceleration phase A2 and the third acceleration phase A3, that is, for the period τ2, or the time interval from the end of the third duration T3 to the end of the fourth duration T4, i.e., for .

[0242] The fourth equation (4) can be a function of the rate of advancement v base of the drive device 7 during the advancement stage E1, from the first positive acceleration tobase , of the second negative acceleration -a min and of the second period t min , as well as the time t, the value of jerk j, the period τ1 between the first acceleration phase A1 and the second acceleration phase A2, the second duration T2, and the third duration T3.

[0243] The fourth equation (4) can also be a function of the result of the third equation (3) for t = T3, i.e. x(T3).

[0244] This fourth equation (4) is:

[0245] (4):

[0246] This fourth equation (4) corresponds to a second portion C2 of the curve C0 of the trajectory during the secondary phase of period τ2.

[0247] A fifth equation (5) of a portion of the trajectory can be predicted for the third acceleration phase A3, that is, for the third period t max, or the time interval from the end of the fourth duration T4 to the end of the fifth duration T5, i.e. for .

[0248] The fifth equation (5) can be a function of the rate of advancement v base of the drive device 7 during the advancement stage E1, from the first positive acceleration to base , of the second negative acceleration -a min and of the second period t min , of the third positive acceleration a max , as well as the time t, the value of jerk j, the period τ1 between the first acceleration phase A1 and the second acceleration phase A2, the period τ2 between the second acceleration phase A2 and the third acceleration phase A3, the second duration T2, and the fourth duration T4.

[0249] The fifth equation (5) can also be a function of the result of the fourth equation (4) for t = T4, i.e. x(T4).

[0250] This fifth equation (5) of a portion of the trajectory is:

[0251] (5):

[0252] This fifth equation (5) corresponds to a first portion C1 of the curve C0 of the trajectory during the third acceleration phase A3.

[0253] A sixth equation (6) of a portion of the trajectory can be predicted for the secondary phase between the third acceleration phase A3 and a new first acceleration phase A1 for a new cycle, i.e. for the period τ3, or the time interval from the end of the fifth duration T5 to the end of the period T6 of the trajectory, i.e. for .

[0254] The sixth equation (6) can be a function of the rate of advancement v base of the drive device 7 during the advancement stage E1, from the first positive acceleration to base , of the second negative acceleration -a min and of the second period t min, of the third positive acceleration a max and of the third period t max , as well as the time t, the value of jerk j, the period τ1 between the first acceleration phase A1 and the second acceleration phase A2, the period τ2 between the second acceleration phase A2 and the third acceleration phase A3, the second duration T2, and the fifth duration T5.

[0255] The sixth equation (6) can also be a function of the result of the fifth equation (5) for t = T5, i.e. x(T5).

[0256] This sixth equation (6) is:

[0257] (6):

[0258] This sixth equation (6) corresponds to a second portion C2 of the curve C0 of the trajectory during the secondary phase of period τ3.

[0259] Finally, the generation process may include a storage step in which the generated control signal and / or one or more parameters representative of the control signal, such as: one or more equations (1) - (6), at least one of the initial parameters or at least one set of initial parameters, at least one acceleration a base , -has min , has max , at least one time datum τ1, τ2, τ3, t base , t min , t max , T1 - T6, at least one speed v0, v base , v min , v max at least one jolt value can be stored in the memory of the conveyor control unit 1. According to a particular example, the calculated trajectory, or portions of the calculated trajectory, can be stored, for example as a table of positions, in the memory of the conveyor control unit 1.

[0260] Thus, when a part 3 is placed on the transport member 5, and the motor is driven so as to follow the trajectory obtained according to the control signal generation process described above, the part 3 advances all the time according to the arrow F1, it continues to advance by inertia during the recoil stage E2 of the drive device 7.

[0261] It has been observed experimentally that the speed of the transported parts is higher when the stroke of the motor is greater.

[0262] Furthermore, both when part 3 starts its movement with a speed greater than or equal to the initial speed of the drive device 7 and when it starts with a speed less than the initial speed of the conveyor 1, it was found that the speed of part 3 tends to align at some point with the speed of the drive device 7.

[0263] Thus, calculating the trajectory from the initial parameters, which are physical parameters, allows for adjustments as close as possible to the optimum. The control signal generation process described above makes it easy to parameterize conveyor 1 at any time by adjusting one or more of the initial parameters.

[0264] These initial parameters can be modified at will to generate new trajectories, within the limit of the existence of a solution (for example, a low jerk value j associated with high accelerations would not allow obtaining a solution of the proposed form).

[0265] A new set of these initial parameters can be tested quickly. This offers much greater freedom when adjusting conveyor 1 than in previous solutions, particularly those with a drive cam, and allows adaptation to one type of part 3 to be transported or another.

[0266] For example, for a fragile part 3, these initial parameters can be adjusted to prevent the conveyor 5 from moving too fast. Conversely, if the parts 3 to be transported are quite robust and have a good coefficient of friction, the initial parameters can be adapted to make the conveyor 5 move faster.

[0267] Furthermore, the calculation can be done on both a translational dimension and a rotational dimension using the same equations previously developed.

[0268] In summary and as already explained, this solution has shown a productivity gain of at least 300% compared to a prior art solution with a drive cam.

[0269] It is also possible with such a solution to reproduce the trajectory followed by a drive cam according to a previous solution, and in this case a gain of around 80% to 100% was observed, attributed to an absence of parasitic vibrations.

[0270] The speed of a transported part 3 can be doubled and be more stable, so that the gap between parts 3 is also more stable compared to prior art solutions.

[0271] In addition, the motion profile is calculated in such a way as to allow the motor to reach the different acceleration values, in particular thanks to the secondary phases known as jerk phases and therefore to the cubic portions or portions similar to cubic curves of the C0 curve which allow a realistic representation of the trajectory to be obtained.

[0272] Finally, when the parameters have been correctly chosen according to the motor's capabilities and the moving masses, the actual trajectory corresponds well to the setpoint (i.e., the analytical trajectory). According to one implementation example, the positioning error of the actual trajectory over time is less than ±0.04 mm.

Claims

1. Method for generating a control signal for a conveyor (1) for transporting parts (3), said conveyor (1) comprising: a transporting element (5) having a transport surface (51) on which the parts (3) to be transported are intended to be placed, and a drive device (7) configured to drive the transporting element (5) in an asymmetric reciprocating motion, the asymmetric reciprocating motion having a displacement in one direction of advance and a displacement in a direction of recoil opposite to the direction of advance, said method being configured to generate a control signal for at least one advancement step (E1) of the drive device (7) at a forward speed (v base), of at least one recoil step (E2) of the drive device (7) at a recoil speed, and of at least one change of direction step (E', E'') between the forward step (E1) and the recoil step (E2), during the change of direction step (E', E''), the forward or recoil speed of the drive device (7) varies until it reaches a zero reversing speed at which the direction of forward or recoil of the drive device (7) changes, characterized in that the control signal comprises a predefined number of trajectory portions corresponding to at least two acceleration phases (A1, A2) of acceleration values ​​(a base , -has min ) respective non-zero and constant over an associated period (t base , t min) and at least one secondary phase called a jerk (j) with a non-zero period (τ1, τ2, τ3) between two acceleration phases (A1, A2), the jerk value (j) being the derivative of the acceleration with respect to time and being constant for all secondary phases, in that at least one change-of-direction step (E', E'') is initiated during at least one secondary phase and the change of direction of forward or backward movement occurs during an acceleration phase (A2), the acceleration (-a min ) being non-zero and constant, and in that the method of generating the control signal comprises: at least one step to establish a predefined number of initial parameters from among at least one acceleration (a base ), at least one time datum, at least one velocity, and one jolt value (j), at least one calculation step of at least one period (t min) from at least one of the initial parameters, and at least one calculation step of at least one portion of the trajectory of the drive device (7) according to a portion-of-trajectory equation (x(t)) associated for a time interval within the period (t base ) of at least one acceleration phase (A1) and the period (τ1) of at least one secondary phase, the equation of the trajectory portion being a function of time (t), of the forward speed (v base ), and at least one parameter from among: at least one initial parameter of which at least one acceleration (a base ), the jerk value (j), at least one period (t base ) of an acceleration phase (A1), at least one period (τ1) between two acceleration phases (A1, A2).

2. A generation method according to the preceding claim, wherein the control signal defines: a first acceleration phase (A1) with a first positive acceleration (a base) constant over a first period (t base ), a second acceleration phase (A2) with a second negative acceleration (-a min ) constant over a second period (t min ), a third acceleration phase (A3) with a third positive acceleration (a max ) constant over a third period (t max ), and in which: the initial parameters include the first positive acceleration (a base ), the second negative acceleration (-a min ), the third positive acceleration (a max ).

3. A generation method according to the preceding claim, wherein the second negative acceleration (-a min ) and the third positive acceleration (a max ) have a respective absolute value which is maximum with respect to the acceleration values ​​reached between two stages of change of direction (E', E'').

4. A generation method according to claim 2 or 3, wherein the first period (t base ) is an initial parameter.

5. A generation method according to any one of the preceding claims, wherein at the advancement stage (E1), the drive device (7) has a positive initial velocity (v0) which increases according to the first positive acceleration (a base ) and which reaches a maximum speed (v max ), the initial speed (v0) of the drive device (7) being an initial parameter.

6. A generation method according to any one of the preceding claims, wherein at least one period (τ1) of a secondary phase between two acceleration phases (A1, A2) is calculated from at least two accelerations (a base , -has min ) and the jerk value (j).

7. A generation method according to claims 4 to 6, wherein: at least the second or third period (t min , t max) is calculated from at least two of the accelerations (a base , -has min , has max ), of the jerk value (j), of the first period (t base ), the initial velocity (v0) of the drive device (7) and the periods (τ1, τ2, τ3) of the secondary phases, and in which the third period (t max ) is a function of the second period (t min ).

8. A generation method according to any one of the preceding claims in combination with claim 2, wherein six trajectory portions respectively associated with the first period (t base ), the second period (t min ), the third period (t max ) and the period (τ1, τ2, τ3) of each secondary phase between two acceleration phases (A1, A2, A3), are calculated according to six equations of respective trajectory portions.

9. A generation method according to any one of the preceding claims in combination with claim 2, comprising at least one step of calculating a first portion of the trajectory of the drive device (7), corresponding to the first acceleration phase (A1) of the first period (t base ), according to a first equation (1) of the associated trajectory portion (x(t)):(1) : ,with v base , the forward speed of the drive device (7) during the forward step (E1), a base , the first positive acceleration,t base , the first period, t, the time.

10. Generation method according to the preceding claim, comprising at least one step of calculating a second portion of the trajectory of the drive device (7), corresponding to the secondary phase between said first (A1) and second (A2) acceleration phases of period (τ1), according to a second equation (2) of trajectory portion (x(t)) associated :(2) : with T1, a first duration corresponding to the first period (t base ),T2, a second duration corresponding to the sum of the first period (t base ) and the period (τ1) of the secondary phase between the first acceleration phase (A1) and the second acceleration phase (A2),v base , the forward speed of the drive device (7) during the forward step (E1), a base , the first positive acceleration, t, time.

11. A generation method according to the preceding claim, comprising at least one step of calculating a third portion of the trajectory of the drive device (7), corresponding to the second acceleration phase (A2) of the second period (t min ), according to a third equation (3) of the associated trajectory portion (x(t)): (3) : with T2, the second duration, T3, a third duration corresponding to the sum of the second duration (T2) and the second period (t min ):vbase , the forward speed of the drive device (7) during the forward step (E1), a base , the first positive acceleration,-a min , the second negative acceleration,t min , the second period, τ1, the period between the first acceleration phase (A1) and the second acceleration phase (A2), j, the value of the jolt, t, the time.

12. Generation method according to the preceding claim, comprising at least one step of calculating a fourth portion of the trajectory of the drive device (7), corresponding to the secondary phase between said second (A2) and third (A3) acceleration phases of period (τ2), according to a fourth equation (4) of trajectory portion (x(t)) associated :(4) : with T2, the second duration, T3 the third duration, T4, a fourth duration corresponding to the sum of the third duration (T3) and the period (τ2) of the secondary phase between the second acceleration phase (A2) and the third acceleration phase (A3), v base , the forward speed of the drive device (7) during the forward step (E1), a base , the first positive acceleration,-a min , the second negative acceleration,t min , the second period, τ1, the period between the first acceleration phase (A1) and the second acceleration phase (A2), j, the value of the jolt, t, the time.

13. A generation method according to the preceding claim, comprising at least one step of calculating a fifth portion of the trajectory of the drive device (7), corresponding to the third acceleration phase (A3) of the third period (t max ), according to a fifth equation (5) of the associated trajectory portion (x(t)): (5): with T2, the second duration, T4, the fourth duration, T5, a fifth duration corresponding to the sum of the fourth duration (T4) and the third period (t max ):v base , the forward speed of the drive device (7) during the forward step (E1), a base , the first positive acceleration,-a min , the second negative acceleration,t min , the second period, a max , the third positive acceleration, τ1, the period between the first acceleration phase (A1) and the second acceleration phase (A2), τ2, the period between the second acceleration phase (A2) and the third acceleration phase (A3), j, the value of the jerk, t, the time.

14. Generation method according to the preceding claim, comprising at least one calculation step of a sixth portion of the trajectory of the drive device (7), corresponding to the secondary phase between the third acceleration phase (A3) and a new first acceleration phase (A1), of period (τ3), according to a sixth equation (6) of associated trajectory portion: (6) with T2, the second duration, T5, the fifth duration, T6, a period corresponding to the sum of the periods (t base , t min , t max ) of the three acceleration phases (A1, A2, A3) and (τ1, τ2, τ3) of the three secondary phases,v base , the forward speed of the drive device (7) during the forward step (E1), a base , the first positive acceleration,-a min , the second negative acceleration,t min , the second period, a max , the third positive acceleration,t max, the third period, τ1, the period between the first acceleration phase (A1) and the second acceleration phase (A2), τ2, the period between the second acceleration phase (A2) and the third acceleration phase (A3), j, the value of the jerk, t, the time.

15. A generation method according to any one of the preceding claims, wherein the control signal of the drive device (7) has a fundamental frequency having at least one substantially parabolic or parabolic portion and / or at least one substantially cubic or cubic portion.

16. A generation method according to any one of the preceding claims, comprising a storage step in which the generated control signal or at least a representative parameter of the control signal is stored in a conveyor control unit (1).

17. Method for controlling a conveyor (1) for transporting parts (3), said conveyor (1) comprising: a transporting member (5) having a transport surface (51) on which the parts (3) to be transported are intended to be placed, and a drive device (7) configured to drive the transporting member (5) in an asymmetric reciprocating motion, the asymmetric reciprocating motion having a displacement in a direction of advancement and a displacement in a direction of recoil opposite to the direction of advancement, characterized in that the control method is configured to control, according to a control signal generated according to a method for generating a control signal according to one of the preceding claims: at least one advancement step (E1) of the drive device (7) at an advancement speed (vbase), at least one recoil step (E2) of the drive device (7) at a recoil speed, and at least one direction change step (E',E'') between the forward step (E1) and the reverse step (E2), during the direction change step (E', E''), the forward or reverse speed of the drive device (7) varies until it reaches a zero reversing speed at which the direction of forward or reverse of the drive device (7) changes.

18. A control method according to the preceding claim, comprising at least one preliminary step for extracting the control signal or at least one parameter of the control signal stored in a memory of a conveyor control unit (1).

19. Conveyor (1) for transporting parts (3) comprising: a transporting member (5) having a transport surface (51) on which the parts (3) to be transported are intended to be placed, and a driven drive device (7) configured to drive the transporting member (5) according to an asymmetric reciprocating motion, the asymmetric reciprocating motion having a displacement in a direction of advancement during at least one advancement step (E1) and a displacement in a direction of recoil opposite to the direction of advancement during at least one recoil step (E2), characterized in that the drive device (7) is configured to be driven according to a driving method according to one of claims 17 or 18.

Images