Method and system for operating and/or monitoring a multi-axis machine

Abstract

A method for determining a response time of a brake of at least one assigned axis of a multi-axis machine includes actuating the axis, switching the brake, and determining a response time between a switching point in time and a response point in time at which a motion state of the axis changes. The method may further include opposing actuation of the axis while the brake is closed, and detecting a mechanical play between opposing maximum deflections of the axis. A method of operating or monitoring a multi-axis machine includes determining a response time and/or detecting mechanical play, and operating the machine or triggering a fault response based on the response time or mechanical play.

Claims

1. A method for determining a response time of a brake of at least one assigned axis of a multi-axis machine, the method comprising: actuating the at least one assigned axis; switching the brake at a switching point in time, whereafter the brake is actuated from an opened state to a closed state, or from a closed state to an opened state; wherein switching the brake includes issuing a command to move the brake from the opened state to the closed state, or from the closed state to the opened state; and determining a response time between the switching point in time and a response point in time at which a motion state of the at least one axis changes.

2. The method of claim 1, wherein the multi-axis machine is one of a robot or a machine tool.

3. The method of claim 1, wherein the brake is switched from an opened state to a closed state, and wherein the response point in time is a point in time at which the rotational speed of the at least one assigned axis is reduced by more than approximately 1 percent relative to the rotational speed at the switching point in time, or at which the assigned axis stops.

4. The method of claim 1, wherein the brake is switched from an opened state to a closed state, and the response point in time is a point in time at which a torque of a drive that actuates the at least one axis and which is necessary to maintain the velocity of the at least one axis increases by more than approximately 1 percent.

5. The method of claim 1, wherein the brake is switched from a closed state to an opened state, and the response point in time is a point in time at which the at least one axis begins to move from rest.

6. The method of claim 1, further comprising: detecting a change of the motion state of the at least one axis with a position, velocity, or acceleration detection device.

7. The method of claim 1, wherein the switching point in time is a point in time at which a switching of the brake is triggered or detected by at least one of a signaling device or an energy technology device.

8. A method of operating a multi-axis machine, the method comprising: determining a response time of a brake associated with at least one assigned axis of the machine, wherein: determining the response time comprises: actuating the at least one assigned axis, switching the brake at a switching point in time, whereafter the brake is actuated from an opened state to a closed state, or from a closed state to an opened state, wherein switching the brake includes issuing a command to move the brake from the opened state to the closed state, or from the closed state to the opened state, and determining the response time between a switching point in time and a response point in time at which a motion state of the at least one axis changes and; operating the multi-axis machine taking into account the determined response time.

9. A method for monitoring a multi-axis machine, the method comprising: determining a response time of a brake associated with at least one assigned axis of the machine, wherein: determining the response time comprises: actuating the at least one assigned axis, switching the brake at a switching point in time, whereafter the brake is actuated from an opened state to a closed state, or from a closed state to an opened state, wherein switching the brake includes issuing a command to move the brake from the opened state to the closed state, or from the closed state to the opened state, and determining the response time between a switching point in time and a response point in time at which a motion state of the at least one axis changes and; triggering a fault response when the determined response time lies outside of a specified range.

10. A controller for operating or monitoring a multi-axis machine, wherein the machine includes at least one assigned axis and an associated brake, the controller having programming code stored on a non-transitory machine readable data medium, the programming code configured to, when executed by the controller, cause the controller to: determine a response time of the brake of the at least one assigned axis of the machine, wherein: determining the response time comprises: actuating the at least one assigned axis, switching the brake at a switching point in time, whereafter the brake is actuated from an opened state to a closed state, or from a closed state to an opened state, wherein switching the brake includes issuing a command to move the brake from the opened state to the closed state, or from the closed state to the opened state, and determining the response time between a switching point in time and a response point in time at which a motion state of the at least one axis changes and; then take at least one of the following actions: trigger a fault response when the determined response time lies outside of a specified range, or operate the multi-axis machine taking into account the determined response time.

11. A computer program product for use with a multi-axis machine, wherein the machine includes at least one assigned axis and an associated brake, the computer program product having programming code stored on a non-transitory machine readable data medium, the programming code configured to, when executed by a controller, cause the controller to: determine a response time of the brake of the at least one axis of the machine, wherein: determining the response time comprises: actuating the at least one assigned axis, switching the brake at a switching point in time, whereafter the brake is actuated from an opened state to a closed state, or from a closed state to an opened state, wherein switching the brake includes issuing a command to move the brake from the opened state to the closed state, or from the closed state to the opened state, and determining the response time between a switching point in time and a response point in time at which a motion state of the axis changes and; then take at least one of the following actions: trigger a fault response when the determined response time lies outside of a specified range, or operate the multi-axis machine taking into account the determined response time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Additional advantages and features are found in the dependent claims and the exemplary implementations, wherein, in partially schematic views:

(2) FIG. 1: shows a sequence of a method according to one implementation of the present invention; and

(3) FIG. 2: shows a robot with a system to execute the method according to one implementation of the present invention.

DETAILED DESCRIPTION

(4) FIG. 1 shows a sequence for a method according to one implementation of the present invention as a function of time t as the abscissa. The ordinate direction shows a solid line with a switching state B of a brake of an axis of a multi-axis robot 2 (see FIG. 2), a dashed line with a torque curve T of a drive of the axis, a dotted-dashed line with a velocity curve n of the axis, and a dotted line with a partially displayed position curve of the axis.

(5) The axis is actuated without braking during a first time period [t.sub.0, t.sub.1]. This involves determining the weight force and friction torques in order to reduce and/or increase the drive torque T as a function of the position during the subsequent determination of the response times and mechanical play. For purposes of a more coherent representation, the weight force and friction influences are disregarded in the exemplary implementation; in particular, the exemplary implementation can refer to the first vertical axis of rotation on robot 2 for illustration purposes.

(6) During a second time period [t.sub.1, t.sub.5], the axis is actuated based on a rotational speed control, wherein a drive torque is limited to a maximum nominal moment T.sub.max of the brake.

(7) The brake is switched to a closed state at a point in time t.sub.2. The first switching point in time t.sub.2 is detected as the point in time at which this switching of the brake is triggered or detected by means of signaling and/or energy technology, for instance by issuing or receiving a corresponding closing signal, or by de-energizing an energy supply of the actively vented brake. FIG. 1 indicates this as a step in the switching state B.

(8) At a point in time t.sub.3, the brake begins to apply a braking effect on the axis. This is initially compensated by a correspondingly increasing drive torque T of the rotational speed-controlled drive until the maximum nominal torque of the brake is reached. The lag between the switching of the brake and the start of its braking effect can for instance be caused by mechanical, hydraulic, pneumatic, (electro-) magnetic, signaling, and/or energy-technology inertia and/or inductivities.

(9) Starting at the point in time t.sub.4, the brake decelerates the axis toward the drive torque limited to T.sub.max, until the axis stops at a point in time t.sub.5. This point in time t.sub.5 is detected by a position or velocity sensor of the axis, and is determined as the first response point in time by the control 1 of robot 2 (see FIG. 2).

(10) The control determines a difference between the first switching point in time t.sub.2 and the first response point in time t.sub.5 as the real-time response time and/or closing time t.sub.close.

(11) During a subsequent third time period [t.sub.5, t.sub.6], the drive actuates the axis in the opposite direction while the brake continues to be closed, initially with the negative maximum nominal torque T.sub.max of the brake and then again with the (positive) maximum nominal torque T.sub.max.

(12) In doing so, the position sensor of the axis detects an individual mechanical play s.sub.1 and/or s.sub.2 each between opposing maximum deflections of the axis (see FIG. 1).

(13) The control 1 uses this information to determine the real-time (total) mechanical play of the brake, for instance by averaging the values s.sub.1, s.sub.2 or by selecting the larger value.

(14) During a subsequent fourth time period [t.sub.6, t.sub.8], the drive actuates the axis while the brake continues to be closed with e.g. 50% of the maximum nominal torque T.sub.max of the brake.

(15) The brake is switched to an open state at a point in time t.sub.7. The second switching point in time t.sub.7 is detected as the point in time at which this switching of the brake is triggered or detected by means of signaling and/or energy technology, for instance by issuing or receiving a corresponding opening signal, or by energizing an energy supply of the actively vented brake. FIG. 1 indicates this as an (inverse) step in the switching state B.

(16) At the point in time t.sub.8, the braking effect of the brake on the drive torque has been reduced to 0.5 T.sub.max, the axis begins to move (n>0). This point in time t.sub.8 is detected by a position or velocity sensor or an accelerometer of the axis, and is determined as the second response point in time by the control 1.

(17) The control 1 determines a difference between the second switching point in time t.sub.7 and the second response point in time t.sub.8 as the real-time opening time t.sub.open.

(18) The control 1 then plans a motion of robot 2 by taking into account these determined real-time response times t.sub.close, t.sub.open by appropriately adjusting the switching points in time for the brake in a control program.

(19) The control 1 also monitors the robot 2 and triggers a fault response, for instance by issuing a fault message when one of the determined real-time response times or the determined mechanical play lies outside of the specified range.

(20) The control 1 and the sensors to detect the switching points in time, the change of the motion state and mechanical plays form a system in accordance with an implementation of the present invention, which include hardware and/or software technology devices arranged to execute the method described herein.

(21) Although exemplary implementations have been explained in the above description, it is hereby noted that a plurality of modifications is possible. In addition, it is hereby noted that the exemplary implementations are merely examples, which are not intended to in any way restrict the scope of protection, the uses, and the construction. Rather, the preceding description gives a person skilled in the art a guideline for the implementation of at least one exemplary implementation, wherein various modifications, in particular with respect to the function and arrangement of the components described, can be undertaken without departing from the scope of protection as indicated by the claims and the equivalent combinations of features.

(22) While the present invention has been illustrated by the description of specific embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.

LIST OF REFERENCE NUMBERS

(23) 1 Control 2 Robot T Drive torque n Rotational speed B Brake switching state Axis position t.sub.( . . . ) (Point) in time