Method and device for carrying out a manipulator process

Description

[0001] The present invention relates to a method and a device for carrying out or controlling a manipulator process, wherein the manipulator has at least one drive means with a motor and a brake.

[0002] Manipulators, especially robots in industrial applications, often have trajectories in which movement phases and holding phases alternate. During the movement phases, the manipulator moves along a path. During the holding phases, the manipulator remains in a pose, for example, while a weld spot is being placed or while waiting for a workpiece to be conveyed. The holding phase is followed by another movement phase, which is then followed by another holding phase, and so on. Other examples are painting and order-picking processes, which are processed automatically by industrial robots.

[0003] During the holding phase, the manipulator is kept active by its drive, so that energy is dissipated for applying the holding forces and keeping the brakes open.

[0004] This energy requirement results in increased energy consumption during operation of the manipulator(s) and represents a significant reduction in the efficiency of today's manipulator arrangements.

[0005] A typical measure to improve efficiency is weight balancing in industrial robots, as proposed in particular in EP 0 914 911 B1. Such weight balancing reduces the differences in potential energies between different robot poses, so that weaker drives and brakes are required, preferably in the robot's base axis, to consume less energy for the same movements.

[0006] DE 103 940 302 T5 discloses a control for closing and opening robot brakes depending on a distance between a stop and a moving part.

[0007] EP 1 974 870 A1 discloses a control of a brake for industrial robots, wherein the brake is equipped with a switch for closing and opening, which allows the brake to be controlled independently of other brakes.

[0008] JP H03 213282 A discloses a method for executing a manipulator process. After initially energizing a servo motor and subsequently releasing a brake, all motion commands of a robot program are executed. If a standby command is provided at the end of the robot program, the brake is applied and the motor is subsequently switched off.

[0009] The object of the present invention is to improve a manipulator process.

[0010] This object is achieved by a method having the features of claim 1. Claim 12 protects a device for carrying out a method according to the invention, claim 13 protects a computer program that executes a method according to the invention, and claim 14 protects a computer program product, in particular a storage medium, comprising such a computer program. The subclaims relate to preferred developments.

[0011] In a method according to the invention, a manipulator process comprising two or more manipulator poses is carried out by one or more manipulators, in particular industrial robots. A manipulator is preferably movable in several degrees of freedom, in particular four, six, or seven degrees of freedom, wherein one degree of freedom is realized in particular by an axis of the manipulator. One or more axes of the manipulator are each equipped with one or more drive means, which have one or more motors and one or more brakes, in particular at least one parking brake, i.e. a brake that is closed without energy.

[0012] During a movement phase, a manipulator pose is approached. A manipulator process within the meaning of the present invention comprises a movement sequence of the manipulator(s), hereinafter referred to as a "trajectory," and can in particular include its description. In addition, a manipulator process can have instructions, rules, and / or interfaces, in particular for controlling a tool, for communication, and / or for (re-)planning the movement sequence. The trajectory can in particular be represented in functional and / or tabular form, in particular in the manipulator control. A manipulator pose can in particular be programmed and / or commanded in advance by an operator, specified externally, and / or generated during the manipulator process. A manipulator pose can in particular comprise a position and / or an orientation of the manipulator.A manipulator pose is preferably described by coordinates in the manipulator's working space, in particular Cartesian, or in the manipulator's joint space, or represented as quaternions. The trajectory up to a manipulator pose to be approached is preferably predetermined, in particular partially predetermined. In particular, an interpolator can be used to create a continuous or discrete target path, in particular in functional and / or tabular form.

[0013] At the end of the movement phase, one or more drive means, preferably the entire manipulator, are stopped so that the axes defined by the stopped drive means no longer execute any movements. Stopping is preferably carried out by the motors and / or by one or more closed brakes of the corresponding drive means. After stopping or while at a standstill, a holding force for the corresponding axis is provided solely by the motors until one or more closed brakes take over this holding force or at least part of this holding force. For the sake of a more compact representation, a (torque) moment, i.e. an antiparallel force pair, is also generally referred to as a force.

[0014] According to the invention, after stopping or standstill, one or more, in particular all, brakes of one or more, in particular all, drive means of the manipulator are applied. Likewise, one or more brakes of one or more drive means of the manipulator can be applied while one or more brakes of another or other drive means are still open. When the brake(s) are applied, the holding force necessary and / or sufficient to bring the corresponding axis of the drive means to a standstill is partially or completely applied by the brake(s). Accordingly, after one or more brakes of one or more drive means are applied, the energy supply to this drive means is partially or completely reduced. Preferably, the electrical current for applying the holding force, by which one or more motors are supplied with energy, is partially or completely reduced.

[0015] At the end of a holding phase, the energy supply of at least one drive means is increased again, in particular in such a way that the holding force previously generated by the brake or brakes of the drive means can be applied by one or more motors and preferably in such a way that the axes operated by the drive means can be moved in accordance with the path and / or target specifications.

[0016] After this increase in energy supply, one or more, in particular all, brakes of one or more, in particular all, drive means of the manipulator are opened so that the manipulator can move again in the axes.

[0017] Subsequently, another manipulator pose is approached, in particular along a target path. In a preferred embodiment, at least one drive means of the manipulator is moved while a brake of another drive means is closed.

[0018] A drive means within the meaning of the present invention comprises one or more motors and one or more brakes. Preferably, a drive means enables movement and / or deceleration of a manipulator axis, in particular by one degree of freedom. Additionally or alternatively, a drive means can have a casing that at least partially surrounds the motor(s) and brake(s) and separates them from the surroundings. Particularly preferably, one or more drive means are at least partially integrated into a manipulator. A drive means can additionally or alternatively have a gear to increase or decrease a torque provided by the motor. Preferably, a drive means has one or more sensors on the drive side and / or output side, in particular one or more position sensors, motion sensors and / or force sensors.

[0019] A motor within the meaning of the present invention can, in particular, be an electric motor. An electric motor can, in particular, be designed to convert electrical energy into mechanical energy. An electric motor is preferably operated with direct and / or alternating current, wherein the alternating current can, in particular, have a specific frequency and / or a specific amplitude. An electric motor is preferably designed as a brushless direct current motor, a synchronous machine, or an asynchronous machine. In particular, a motor can have electronic commutation. A motor is preferably equipped with an inverter and / or a PWM amplifier.

[0020] A brake within the meaning of the present invention preferably serves to apply a holding torque or a portion of a holding force to hold a manipulator axis at a standstill. As explained above, a (torque) torque is also generally referred to as a force in this context.

[0021] Advantageously, holding one or more manipulator axes at a standstill using a brake requires less energy than holding these manipulator axes using the corresponding motor(s) of the drive means. This results in improved efficiency when standstill is brought about by such a brake and not, or not exclusively, by a motor. In addition, a brake can be configured to slow down the speed of the manipulator axis. A brake is preferably designed as a safety brake. A safety brake closes when the energy supply drops below a limit value and applies the corresponding holding force, in particular without any further energy supply. Preferably, the energy supply to the brake is completely interrupted to close at least one brake.Such a brake further improves efficiency when the manipulator is held stationary by one or more brakes rather than a motor. A brake can be designed as a spring-loaded brake, wedge brake, eddy current brake, electromotive brake, (permanent) magnetic brake, magnetic powder brake, and / or pneumatic brake.

[0022] A power supply within the meaning of the present invention supplies one or more, in particular all, drive means of one or more manipulators, in particular with electrical energy. The power supply can be fed from an energy network, in particular a public one, and / or an autonomous energy network. Additionally or alternatively, a power supply can be fed from at least one battery arrangement and / or an alternative energy storage device, in particular a mechanical energy storage device. Preferably, several drive means, in particular all drive means of one or more manipulators, are connected to a power supply. Particularly preferably, the power supply has an intermediate circuit which, via an intermediate circuit voltage, provides energy for the motors, the brakes and / or other components of one or more drive means, in particular one or more manipulators.Preferably, the power supply is connected to a controller. The power supply is configured to reduce and / or increase the energy supply to one or more drive means, in particular to one or more motors and / or to one or more brakes of these drive means. Preferably, the power supply provides sufficient energy to operate one or more drive means, particularly preferably to operate one or more manipulators, in particular including additional peripherals, e.g., controller, safety cell, tool, lighting, and / or communication devices.

[0023] In a preferred embodiment, the steps described above are repeated one or more times, so that the manipulator follows a trajectory with two or more stopping phases, during which one or more brakes are applied. This can provide the particular advantage of using stopping phases of various types to save energy.

[0024] In a preferred embodiment, the brake is closed and / or opened based on at least one of several criteria. According to a first aspect, the brake is closed and / or opened based on a state criterion. A state within the meaning of the present invention can be a physical state of the manipulator or an external device and / or a combination of several such states. Additionally or alternatively, a state can be characterized by a configuration of properties, in particular of the manipulator and / or an external device. Preferably, a state can be determined by a configuration of a state diagram and / or a sequence control, which serve in particular to operate a manipulator and / or an external device and in particular describe the status of a workflow.In particular, a state can be a state of a manipulator, a manipulator controller, a manipulator process, a tool of the manipulator, a master controller, and / or a device from the manipulator's environment that interacts with the manipulator. A state criterion provides the advantage that the brake can be applied and / or released when a specific configuration of the manipulator or its environment occurs.

[0025] According to a second aspect of this embodiment, the brake is applied and / or released based on a signal criterion. A signal within the meaning of the present invention can in particular be a sign with a specific meaning, which the signal preferably receives through a previously agreed arrangement or through a regulation. In particular, information can be communicated through a signal. Such information can preferably contain data about the manipulator, in particular about its components and / or about external devices. Additionally or alternatively, such information can contain data about a machining process. Particularly preferably, a signal conveys information from a manipulator controller and / or an external controller. Additionally or alternatively, a signal contains information about instructions from one or more operators, in particular a braking instruction, and / or about their status.Preferably, a signal contains information that people and / or objects are located in the danger zone of the manipulator(s). In particular, a signal can contain information about the attention of an operator located in the vicinity of the manipulator and, for example, communicate a corresponding stop instruction if the operator is inattentive. In particular, a signal can be a signal from a manipulator control, a manipulator process, a tool control, a master control and / or a device from the environment of the manipulator that interacts with the manipulator. A signal criterion offers the particular advantage that the brake can be controlled using easily interpretable information, whereby this simple information can in particular represent a representation of more complex information.

[0026] According to a third aspect of this embodiment, the brake is closed and / or opened based on a time criterion. A time within the meaning of the present invention can be an absolute time or a relative time. Preferably, a time is a process time of a process of the manipulator or of an external device. Additionally or alternatively, a time can be a holding time, in particular a holding time that has elapsed since a stoppage, preferably of one or more drive means of a manipulator and / or an external device. Preferably, a time is a pause time. A pause time preferably describes the duration of a holding phase of a manipulator and / or an external device between two movement phases. A pause time can in particular describe the duration between the closing of a brake and the opening of a brake.A time criterion advantageously offers the possibility of transmitting a close-open instruction by means of a single piece of information, in particular the duration of a holding phase.

[0027] According to a preferred embodiment, two or more criteria are evaluated to close and / or open the brake(s) of one or more drive means. The evaluation can be carried out in parallel and / or in a chain, in particular serially. Parallel evaluation of two or more criteria can advantageously increase the reliability of braking operation. Serial evaluation of two or more criteria can advantageously control the closing and / or opening of a brake more precisely. Parallel evaluation can be implemented in particular by an "OR" operation of the criteria, while serial evaluation can be implemented by an "AND" operation of the criteria.

[0028] According to a preferred embodiment, at least one criterion that is evaluated for closing and / or opening the brake is changed during the manipulator process. The change in the criterion is preferably controlled by a learning process, which is carried out in particular in the manipulator control and / or on an external device. Particularly preferably, a time, in particular a pause time, results as a result of a machine learning process. In particular, the learning process can observe one or more manipulator processes and estimate the length of a future pause time based on the observed manipulator processes. The change in the criterion can be event-driven, in particular by a newly available learning result, and / or periodic and / or continuous. By changing a criterion during the manipulator process, the advantage can arise in particular that redundant information within the trajectory, e.g.similar, in particular identical, holding phases can be used to improve efficiency, in particular without having to know the duration of the holding phases in advance.

[0029] In a preferred embodiment, a safety device monitors and / or controls the opening and / or closing of the brakes using safe technology. For this purpose, the architecture for controlling one or more brakes preferably meets a safety integrity level, such as that specified in the standards IEC 61508 or EN ISO 13849. Safe brake control offers the advantage of a safe operational stop, in particular of one or more axes, preferably of the entire manipulator. A safe operational stop may be necessary for certain manipulator processes, especially if they involve interactions with one or more people.

[0030] Further advantages and features emerge from the subclaims and exemplary embodiments. This is shown, partly schematically: Fig. 1: the time course of the speed and the power requirement of an example trajectory of a manipulator process according to an embodiment of the present invention Fig. 2: the sequence of a method for controlling a manipulator according to an embodiment of the present invention.

[0031] Fig. 1 shows a section of a trajectory of a manipulator process performed by an industrial robot, with the speed plotted against time and two different power curves P and P' according to two time criteria. Until time t=1, the robot's axis 3 moves at a positive, constant speed. ḟ >0. At time t1 a stop is commanded and the speed of axis 3 decreases linearly to ḟ=0. From time t2, axis 3 of the robot is at a standstill.

[0032] The first time criterion uses the holding time th to decide whether to activate and / or deactivate the brakes and the motor. The power curve is shown by the dotted line. After the holding time th has elapsed, the robot's safety brake is de-energized at time t3 and is applied. As a result, the power consumption P' of axis 3 is reduced at time t3 by the power P' required to open the brake. After the brake is applied, the motor is also de-energized. This means that the entire drive unit of axis 3 of the robot is de-energized. No energy is consumed until the power supply to the motor is activated. At time t6, the brakes are released, which leads to a corresponding increase in the power requirement P' and the holding torque is reduced during t>t6 and t <t7 wieder vom Motor aufgebracht. Die neue Bewegungsphase startet zum Zeitpunkt t7, ab dem die Geschwindigkeit der Achse 3 wieder linear zunimmt.

[0033] The second time criterion uses the pause time tp to decide whether to activate and / or deactivate the brakes and the motor. The power curve is shown by the dashed line. The closing of the brake on axis 3 is synchronized with the complete pause time tp of the industrial robot. The brake is closed at time t2 and not opened again until time t7. After verifying that the brakes have closed correctly, the power supply to the motor is also interrupted. Until the power supply is reactivated, axis 3 is held solely by the brake. The power supply to the motor is reactivated at time t6.

[0034] The illustrated time criteria are preferably combined with other criteria, e.g., signal criteria and / or state criteria. In preferred embodiments not shown, the decision to apply and / or release the brakes depends on one or more signal criteria and / or one or more state criteria. In particular, signal and / or state criteria can be combined with one another.

[0035] Fig. 2 shows a flowchart of a manipulator process with parameterized brake control to improve the efficiency of the manipulator process. The manipulator is initially in a position where the deflection of axis 3 is zero. f = 0, and the speed is also zero, ḟ =0. First, a pause is parameterized by the start time tp_start and the duration of the pause tp. In addition, the movement speed ḟ read out.

[0036] Then, axis 3 of the robot is moved by the mov() function. Upon a signal event (interrupt), a braking process is commanded by the stop() function so that axis 3 comes to a standstill at time tp_start. The brakes are activated when the robot's speed ḟ =0 and the time tp_start has been exceeded. After the brakes are applied, the power supply is interrupted by pow(off). After the pause time has elapsed, the power supply is first reactivated, then the brakes are released. Following this, the parameters are updated and the next movement phase begins. Reference symbol list

[0037] tTime t1-t7absolute times thhold time tppause time f Position of axis 3 of the manipulator ḟ Speed of axis 3 PPower consumption of axis 3 at the first time criterion P'Power consumption of axis 3 at the second time criterion

Claims

1. A method of carrying out a manipulator process, which comprises at least two manipulator poses, by a manipulator, in particular by a robot, which comprises at least one drive means which comprises a motor and a brake, wherein the method comprises the following steps: (S10)moving towards a manipulator pose;(S20)stopping at least one drive means;(S30)applying at least one brake of said drive means;(S40)reducing the supply of energy to the drive means;(S50)increasing the supply of energy to the drive means;(S60)releasing the applied brake;(S70)moving towards a further manipulator pose; wherein the manipulator process comprises a movement sequence of the manipulator.

2. The method according to claim 1, characterised in that the steps (S20) - (S70) are repeated.

3. The method according to claim 1, characterised in that the brake is applied and / or released on the basis of at least one of the following criteria: - a time criterion; - a signal criterion; - a status criterion.

4. The method according to claim 3, characterised in that the brake is applied and / or released on the basis of at least two of the criteria.

5. The method according to claim 3 or 4, characterised in that a time criterion is specified on the basis of at least one of the following times: - an absolute time; - a process time; - a holding time since the stopping (S20); - a pause time between the stopping (S20) and the releasing (S60) of the brake.

6. The method according to any one of claims 3 to 5, characterised in that a signal criterion is specified on the basis of at least one of the following signals: - a signal from a manipulator control facility; - a signal from a manipulator process; - a signal from a tool control facility; - a signal from a master control facility; - a signal from a device in the surroundings of the manipulator, which device interacts with the manipulator.

7. The method according to any one of claims 3 to 6, characterised in that a state criterion is specified on the basis of at least one of the following states: - a state of the manipulator; - a state of a manipulator control facility; - a state of a manipulator process; - a state of a tool of the manipulator; - a state of a master control facility; - a state of a device in the surroundings of the manipulator, which device interacts with the manipulator.

8. The method according to any one of claims 3 to 7, characterised in that at least one criterion is changed, in particular adapted, during the manipulator process.

9. The method according to any one of the preceding claims, characterised in that at least one further drive means of the manipulator moves while the brake is applied.

10. The method according to any one of the preceding claims, characterised in that in order to apply at least one brake, a supply of energy to the brake is reduced, in particular interrupted.

11. The method according to any one of the preceding claims, characterised in that a safety device monitors the releasing and the applying of the brakes.

12. A device for controlling a manipulator, in particular a robot, characterised in that the device is set up for carrying out a method according to any one of the preceding claims.

13. A computer program which executes a method according to any one of claims 1 to 11 when it is run in a device according to claim 12.

14. A computer program product which comprises a program code which is stored on a machine-readable medium and which comprises a computer program according to claim 13.