GB2363861A

GB2363861A - Processing an object, eg a workpiece, by a tool

Info

Publication number: GB2363861A
Application number: GB0014981A
Authority: GB
Inventors: Risto Virtanen; Tarmo Linna; Anders Oeblom
Original assignee: ROBOTIC TECHNOLOGY SYSTEMS PLC
Current assignee: ROBOTIC TECHNOLOGY SYSTEMS PLC
Priority date: 2000-06-19
Filing date: 2000-06-19
Publication date: 2002-01-09
Also published as: GB0014981D0

Abstract

The object 9 is processed, eg milling, boring, reaming, cutting, deburring, grinding, polishing, finishing, painting, by the tool 11 along a path of relative movement between the tool and the object. A non-contacting sensor 10, eg using laser beam, infrared or radio wave measurement, provides first information of the relative position of the tool and object. Predefined information relating to the object, such as a limit depth of penetration of the tool is provided as second information and a path of relative movement of tool and object is generated for controlling the process.

Description

2363861 Processing an object

Field of the Invention

The present invention relates to processing of an object, such as a workpiece, by a tool.

Background of the Invention

During manufacture of goods the workpieces may be subjected to various stages of processing by one tool or several tools The processing may include operations where a tool is brought into a contact with a surface or boundary of a workpiece to be processed Appropriate tools may be used, for example, for machining operations such as milling, tooling, boring, reaming, cutting, deburring, grinding, polishing, finishing, painting, brushing and so on The tool may also be arranged to treat the object without being in direct contact with the surface thereof Such processing includes, for example, operations such as spraying, washing, laser beam cutting or water jet cutting and so on It should be appreciated that in this specification the term 'tool' refers to any device that may be used for processing an object.

A tool is typically attached to a tool holder assembly The tool holder assembly may be moved by an actuating means adapted to provide movement of the tool relative to the workpiece The tool may be attached fixedly to a tool holder.

The tool may also be rotated or otherwise moved (e g.

repeatedly tilted) by the tool holder The tool holder assembly typically comprises means for providing a firm grip of the tool so that the drive force that is required for the movement of the tool relative to the object can be properly transmitted to the tool In addition, the tool typically needs to be held firmly in order to prevent the position thereof to change relative to the tool holder The skilled person is aware of various possible alternatives for the gripping means, and thus they will not be explained in more detail.

The tool holder assembly may be attached to an actuating apparatus that is adapted to move the tool holder assembly relative to the object to be processed by the tool The actuators include industrial robots and manipulators and similar apparatus capable of moving the tool holder assembly.

The movement may be provided in a three dimensional space (e.g in x,y,z co-ordinates) The actuator may be provided with six or even more degrees of freedom Some actuators are arranged to provide a movement that is limited in directions (for example, movement enabled only in one or two, such as only in vertical and/or horizontal or x and y axis directions).

As mentioned above, an object may be subjected to various processing operations by a tool that is moved by an actuator, such as a six axis robot, and/or tool holder relative to the object To be able to move the tool correctly and accurately relative to the object, the actuator and/or tool holder typically operates in accordance with a predefined set of instructions More particularly, the movement of the tool is typically controlled by a controller that follows a program code The controller instructs various components of the processing apparatus such that the tool is moved relative to the object in a predefined manner The program may be based, for example, on a prewritten program code and/or on other information obtained e g through a machine vision system The skilled person is aware of various possibilities to control the operation of an actuator, and thus the conventional control function as such is not discussed here in more detail.

The program is run such that the tool is moved relative to the workpiece in order to remove a predefined amount of material from the surface thereof and to provide predefined final geometry of the object (shape and dimensions) The program may be retrieved from a program library, e g after recognition of the object by a machine vision system.

In some machining applications the actual surface contour of the workpiece may not previously known by the machining system For example, the initial workpiece may have a rough and/or non-uniform shape in the beginning of the processing.

Due top various reasons it may be impossible or at least difficult to have any accurate beforehand knowledge of the shape of the surface and/or accurate dimensions of the initial workpiece An example that relates to a specific field of manufacture is machining of substantially large moulds, such as boat moulds A base of the mould can be made from polystyrene or similar material whereafter appropriate further material is sprayed on top of the base material for producing the cover material of the mould To provide the final shape of the mould, the sprayed material needs to be machined into the final geometry However, the spraying of material onto a complex surface produces an initial contour that is not known to the controller It may not be possible to provide adequate beforehand information of the shape and dimensions of the sprayed mould before initiating the process for removing the excess material from the surface of the mould.

Typically the workpieces are machined such that material is removed in layers In other words, the machining process is accomplished such that the machining procedure progresses in subsequent work cycles until enough material has been removed and the final dimension and/or form has been achieved In order to machine workpieces as effectively as possible, it is advantageous to keep the number of subsequent work cycles over the same region of the workpiece as low as possible and to remove as much material as possible during each cycle In addition, the machining parameters, such as the power, rotation speed of the tool, and the type of the tool, need to be set in accordance with the machining depth The machining depth refers to the depth the tool is penetrated into the material The amount of material removed from the object depends on the machining i e the penetration depth.

Substantially different parameters may be required at various stages of the machining cycles, such as for the rough machining at the beginning (the first layers to be removed) and for the finishing stages (the last layer) of the machining operation.

If the contour of the surface and/or the actual outer dimensions of the workpiece are not known at the beginning of the machining, the machining tool may not be used in a most efficient way For example, the tool may "machine air" for a substantial portion of the first few working cycles The controller may also bring the tool too close to the object.

This may lead into serious damages of the tool, machining apparatus, and/or the workpiece.

Summary of the Invention

The embodiments of the present invention aim to address one or several of the problems that relate to processing an object by means of a tool.

According to one aspect of the present invention, there is provided a method for processing an object by a tool attached in a tool holder assembly, comprising: providing relative movement between the tool and the object to be processed by the tool; providing first information that associates with the relative position between the tool and the object by means of a non-contacting sensor provided in association with the tool holder assembly; processing the first information together with second information that associates with the object to generate a path of relative movement between the tool and the object based on said processing of the first and second information, said second information being obtained from another source of information; and processing the object by the tool along the generated path of relative movement.

According to a more specific embodiment the method comprises defining a processing depth limit based on said second information and monitoring if the processing depth limit is to be exceeded The processing by the tool may be applied to the object in a relatively uniform depth relative to the surface of the object throughout a working cycle of the tool based on the first information unless the monitoring indicates that the processing depth limit is to be exceeded in a location on said path of relative movement The object may be processed in said location based on said second information to a depth that does not exceed the processing depth limit.

The processing of the first information and the second information may comprise generation of a path of relative movement between the tool and the object, said path of movement being defined to be located in a region that is between a path of movement that would have been generated based solely on the first information and the path of movement that would have been generated based solely on the second information.

The sensor may provide an information signal that associates with the distance between the tool holder assembly and the surface of the object The sensor may also provide an additional or alternative information signal that associates with the orientation of the tool holder assembly relative to the surface of the object The information provided by the sensor may be based on determination of the distance between the surface of the object and the sensor by means of at least one laser beam generated by the sensor.

The processing depth limit may be defined based on information of the geometry of the object.

In a final working cycle the path of relative movement between the tool and the object may be based solely on the second information.

At least one of the processing parameters may be varied such that a substantially similar amount of material is removed from the object regardless the processing depth of the tool.

According to another aspect of the present invention there is provided a system for processing an object, comprising: a tool for processing the object; actuator apparatus for providing a relative movement between the tool and the object; a tool holder assembly for holding the tool; a non-contacting sensor for providing first information regarding relative position between the surface of the object and the tool; a source of second information that associates with the object; and a controller that is adapted to process said first information together with said second information for generation of a path of relative movement between the tool and the object for processing of the object by the tool along said path of relative movement.

The system may be adapted to perform the operation discussed above The tool may be adapted to remove material from the object The tool may be adapted to spray material on the object The tool holder assembly may comprise a spindle apparatus for providing rotation of the tool The spindle apparatus may consists of a high speed spindle The actuator apparatus may be movable relative to the object The tool holder assembly may be provided with automatic tool change function The system may also comprise machine vision means for producing information of the object based on an image of the object.

The embodiments of the invention may provide a processing arrangement which avoids the above discussed disadvantages.

The processing arrangement nay not require accurate beforehand information of the surface contour.

Brief Description of Drawings

For better understanding of the present invention, reference will now be made by way of example to the accompanying drawings in which:

Figure 1 shows a system employing an embodiment of the present invention; Figure 2 shows a schematic presentation of the operational principles in accordance with an embodiment of the present invention; Figure 3 is a flowchart illustrating the operation of one embodiment of the present invention; and Figures 4 and 5 illustrate further exemplifying embodiments of the invention.

Description of Preferred Embodiments of the Invention

Reference is made to Figure 1 which shows a machining system in accordance with an embodiment of the present invention The machining system includes an industrial robot 1 for actuating a tool holder assembly 3 The structure and operation of an industrial robot is known by the skilled person A robot typically comprises a frame portion and one or several swivelling and/or rotational arms so that it is capable of providing different movements of the tool in a three dimensional working space thereof The various possibilities for rotational and/or pivotal movement of the robot 1 of Figure 1 are indicated by the two-headed arrows.

The robot may be enabled to move the tool in a six axis co- ordinate system i e the robot may be provided with six degrees of freedom More particularly, the robot of Figure 1 is provided with a first arm 5 that is pivotally attached to a frame portion 6 and a second or outer arm 4 that is attached pivotally to the first arm 5 A further pivoting point 7 is arranged at the end of the outer arm 4 A short mounting arm or fixture 8 projects from the pivoting point 7 and provides an attachment point for the tool holder assembly 3 The mounting arm of a robot is sometimes referred to as a wrist.

The mounting arm 8 typically revolves around the axis thereof, as is illustrated by the associated two-headed arrow The rotational and/or swivelling movements of the various components of the robot may be provided by suitable actuators, such as by servomotors and/or pneumatic or hydraulic cylinders.

Figure 1 discloses also a workpiece 9 to be processed by the machining system The workpiece 9 may be supported by any appropriate supporting means, such as by an appropriate fixed support or by a conveying apparatus It is also possible to arrange the workpiece to be supported by another actuator device or by a conveyor arrangement so that the workpiece 9 may be moved in a controlled manner relative to the tool 11.

Therefore it should be understood that while in the exemplifying embodiments the tool 11 is moved relative to the object 9, the relative movement between the tool and the object may also be provided by moving the object or by moving both the object and the tool.

A control unit 2 of the robot 1 is also shown The control unit 2 is arranged to process information concerning the object 9 to be processed by means of the robot 1 A part of the information may be retrieved/received from an external database or from an imaging apparatus of a machine vision system (not shown in Figure 1) via an appropriate communication media The controller 2 typically includes required data processing and storage capability, such as an appropriate central processing unit (CPU) The central processing unit may be based on microprocessor technology As a more practical example, the controller unit may be based on a Pentiumr T processor, even though a less or more powerfull processor may also be employed depending on the requirements of the system and the objects to be handled Depending on the application, the controller 2 may be provided with appropriate memory devices, drives, display means, a keyboard, a mouse or other pointing device and any adapters and interfaces that may be required In addition, if the processing of the object 9 is based on information received from e g a camera of a machine vision system, an appropriate imaging software is typically required The controller may also be provided with a network card for installations where the machining system is connected to a data network, such as to a network that is based on use of Internet Protocol (IP) for data transporation.

A connection is provided between the controller 2 and the robot 1 for transmission of data between the robot and the controller.

The tool holder assembly 3 may comprise a spindle for rotating the tool 11 The spindle may be driven by an appropriate motor 12 that is preferably provided at the other end of the spindle housing The most commonly used alternatives for the motor are at the present electric, pneumatic and hydraulic motors, although other possibilities are not excluded Although it is not necessary in all applications, the rotation of the tool around the rotational axis thereof may be provided in two directions The skilled person is familiar with the operation and structure of the various spindle arrangements, and thus the internal parts within the spindle housing are not shown or explained in more detail It is sufficient to note that a spindle apparatus may comprise a spindle portion within the housing and a motor 12 arranged to provide the drive force for the rotating tool 11 at the other end of the spindle housing.

The rotating tool 11 may be attached to the spindle by means of a chuck, a mandrel or other appropriate clamping device (not shown) The rotating machining tool 11 is arranged to rotate around a so called tool centre line TCL It should be appreciated that other type of construction for the provision of the rotation may also be used.

A reference is now made also to Figure 2 illustrating in more detail the principle of controlling the movement of the tool 11 relative to the object in accordance with an embodiment of the present invention For clarity reason the actuator apparatus has been omitted from Figure 2 The direction of movement of the tool holder assembly 3 is indicated by the arrow shown on top of the assembly.

The workpiece 9 consist of a base portion 20 and material 21 that has been sprayed on the surface 22 of the base portion The solid line 23 shows the contour of the sprayed portion 21 after the spraying has been completed and before any machining operations have been initiated The initial contour of the surface 23 is of complex, uneven geometry and is not known to the controller of the machining system Line 25 illustrates the finished surface of the object, i e the target surface geometry that is to be achieved by one or several working cycles of the tool As can be seen, the finished object 9 consist of the base portion 20 and of a substantially even layer of coating material 21 that has been sprayed on top of the base portion 20.

The tool holder assembly 3 is provided with a non-touching sensor 10 The sensor is arranged to scan or track the distance between the surface 23 and the tool holder assembly 3 (and thus the relative position between the tool 11 and the workpiece 9) along the contour of the curved surface 23 The sensor 10 may be based e g on laser beam measurement techniques The sensor may also use infrared or radio wave measurement techniques or any other appropriate technique that enables determination of the position of the tool relative to the object.

In addition the distance between the surface 23 and the sensor 10, the sensor may provide further information, such as the orientation of the tool holder assembly 3 relative to the object, i e the angle between the tool centre line and the surface of the object The sensor 10 may be used for enabling the actuator to maintain a predefined distance and orientation of the tool 11 along the curved surface 23 of the object 9.

The orientation information relative to the surface may be based on measurements by three laser beams More particularly, the controller unit 2 may control the movements of the robot 1 based on information received from the sensor 10 so that the tool follows the contour of the surface for removing material from the surface An example of an appropriate orientation and displacement sensor (ODS) is Dyna Track TM sensor module that is offered by Intelligent Machine Concepts LLC, USA However, it should be appreciated that any other sensor arrangement that is capable of providing information concerning the relative position between the tool and the surface of the object may be used herein.

If the tool 11 is controlled based on the information from the sensor 10, it may progress on the surface of the object such that substantially similar amount of material is removed throughout the path of movement of the tool during a working cycle In other words, the movement of the tool holder 3 can be controlled adaptively based on information produced by the sensor 10 The adaptively generated path of movement of the tip of the tool is shown by the dashed line 24 in Figure 2.

The working cycle refers to one set of movements of the tool relative to the workpiece that is accomplished to remove a layer of material.

In Figure 2 a working cycle, if controlled solely based on information obtained by means of the sensor 10, would remove all the material between lines 23 and 24 As is also shown by Figure 2, the contour of the complexly shaped surface 23 may vary such that the tip of the tool may penetrate in portions of the path of movement thereof excessively deep into the object 9, thereby removing too much material from the surface of the object in these locations.

To prevent the machining apparatus to penetrate "too deep" into the object while allowing as efficient removal of material wherever it is possible, the control unit 2 may be adapted to monitor for a predefined threshold machining depth or processing limit relative to the object More particularly, while the machining may be applied to the object in a relatively uniform depth relative to the surface of the object throughout a processing cycle based on the information from the sensor 10, a separate monitoring process may be employed to indicate if the threshold depth is to be exceeded in the path of travel of the tool tip After such an indication the machining is applied only to a depth that does not exceed the threshold depth By means of this it is possible to remove as much as possible material in locations where the threshold machining depth will not be exceeded while avoiding penetrating the machining tool too deeply in locations where this could occur This type of control operation that is based on two different sources of information may be referred to as online contour tracking (OCT).

In Figure 2 the threshold depth may be defined to be the final geometry 25 The threshold depth may also be any other depth, such as the predefined geometry indicated by a dotted line 26.

In the latter case some material is left for a final or finishing working cycle The final working cycle will then produce the final geometry 25 and may be controlled solely based on information of the final geometry of the object In those locations where the entire machining capacity cannot be used, the tool may be penetrated only to the threshold level or to another predefined depth that depends on predefined machining information The predefined information may include the final geometry of the object, predefined'parameters for the machining depending the available machining depths, information of the initial geometry of the workpiece for the object and so on The predefined information may be stored in an appropriate database, such as in the machining programme library of the control unit 2.

According to an embodiment the geometry of the surface that results from a machining cycle is smoothened from the initial surface geometry by combining information from the sensor 10 and predefined information of the object and machining along a path that is between the path that would have been generated based on information from the sensor and a path that would have been generated solely based on the information of the object This embodiment may be advantageous in operations such as painting or coating by a spraying tool The "contour smoothening" may also be applied to various machining operations.

One or more of the machining parameters may be changed adaptively For example, the rotational speed the tool may be varied or the speed of movement in which the tool progresses relative to the object may be changed depending on the machining depth so that a substantially similar amount of material can be removed from the object regardless the machining depth.

As shown by the flowchart of Figure 3, the sensor 10 scans the surface of the object while the tool 11 is moved relative to the object The control unit 2 is provided with a information signal that associates with the relative position between the tool tip and the surface The control unit processes the information together with some further information concerning the target geometry that is obtained from a different source of information than the sensor The information input into the controller is processed to obtain one or more of the machining parameters and/or to generate a path of movement of the tool.

An embodiment in which the processing of the object comprises removal of material by cutting the object by means of a rotating tool will now be discussed with reference to Figure 4 In machining operations such as cutting it is advantageous if the tool 11 can be pressed against the object 9 at a location that is as close to the spindle 13 of the tool holder 3 as possible In other words, in some machining application it is advantageous if the free length of the tool between the spindle 13 and the object 9 can be kept in its minimum The system can be arranged to adaptively follow the contour of the curved object based on information from the sensor In Figure 2 the sensor is integrated within the tool holder assembly 3.

The sensor generates two scanning beams 40 and 41 that are directed towards the object The two beams are employed in order to provide information of the distance and orientation of the tool holder assembly relative to the object The machining operation may be optimised based on said information.

It may be that the object 9 contains restrictive features or obstacles that prevent the adaptive minimisation of the free length of the tool through the entire machining path In Figure 4 the object comprises a bracket 42 that projects from the surface of the object such that the bracket hinders the tool holder to pass it if the free length of the tool is kept in its minimum To be able to continue the cutting by the tool 11 in the direction of the arrow shown on top of the holder assembly 3, the distance between the tool holder and the object needs to be increased so much that the bracket 42 may be passed This may be accomplished based on predefined information of the object, the information including the geometry of the bracket While the surface of the object may be followed adaptively based on the information provided by means of the beams 40 and 41, the controller will interrupt the adaptive machining for the section including the bracket.

Instead, for this section the machining may be based on predefined parameters so that the free length of the tool is not optimised but that the bracket 42 may be passed while continuing the machining of the object 9 by the tool 11.

It should be appreciated that the above described embodiment for free minimisation of the free length of the tool may be embodied in other machining applications than the above described, where appropriate, such as in grinding or deburring of edges of a workpiece The distance minimisation may also be applied on other types of processing, such as spraying coating material or paint or cleaning fluid on the object by an appropriate spraying tool.

Figure 5 shows a further embodiment in which the machining system comprises more than one robot 6 The robots may be partially or entirely controlled by a common controller unit (not shown in Figure 5) A robot may also be mounted on linear tracks or guides 50 so as to enlarge the working area thereof.

The robot may be mounted movably on the tracks for enabling processing of substantially large object such as moulds for boats or other vessels.

According to a further embodiment the tool holder assembly is provided with automatic tool change function The tool change may be based on basic concept of changing the tool in the tool holder to another tool or to a concept of changing the tool holder to another tool holder.

A high speed spindle apparatus may also be used for rotating tools The high speed spindle apparatus enable rotational speeds of the tool that are in the order of 50000 1/min or higher.

It should be appreciated that whilst embodiments of the present invention have been described in relation to an industrial robot, the embodiments of the present invention are applicable to any other suitable type of actuator apparatus capable of moving the tool holder assembly.

It is also noted herein that while the above describes exemplifying embodiments of the invention, there are several variations andmodifications which may be made to the disclosed solution without departing from the scope of the present invention as defined in the appended claims.

Claims

1 A method for processing an object by a tool attached in a tool holder assembly, comprising:

providing relative movement between the tool and the object to be processed by the tool; providing first information that associates with the relative position between the tool and the object by means of a non-contacting sensor provided in association with the tool holder assembly; processing the first information together with second information that associates with the object to generate a path of relative movement between the tool and the object based on said processing of the first and second information, said second information being obtained from another source of information; and processing the object by the tool along the generated path of relative movement.

2 A method as claimed in claim 1, comprising defining a processing depth limit based on said second information and monitoring if the processing depth limit is to be exceeded, wherein the processing by the tool is applied to the object in a relatively uniform depth relative to the surface of the object throughout a working cycle of the tool based on the first information unless the monitoring indicates that the processing depth limit is to be exceeded in a location on said path of relative movement, and processing the object in said location based on said second information to a depth that does not exceed the processing depth limit.

3 A method as claimed in claim 1 or 2, wherein the processing of the first information and the second information comprises generation of a path of relative movement between the tool and the object, said path of movement being defined to be located in a region that is between a path of movement that would have been generated based solely on the first information and the path of movement that would have been generated based solely on the second information.

4 A method as claimed in any preceding claims wherein the tool is moved relative to the object.

A method as claimed in any preceding claim, wherein the object is moved relative to the tool.

6 A method as claimed in any preceding claim, wherein the processing comprises removing material from the object by means of the tool.

7 A method as claimed in any preceding claim, comprising rotating the tool by a spindle apparatus of the tool holder assembly.

8 A method as claimed in any preceding claim, wherein the sensor provides an information signal that associates with the distance between the tool holder assembly and the surface of the object.

9 A method as claimed in any preceding claim, wherein the sensor provides an information signal that associates with the orientation of the tool holder assembly relative to the surface of the object.

A method as claimed in any preceding claim, wherein the information provided by the sensor is based on determination of the distance between the surface of the object and the sensor by means of at least one laser beam generated by the sensor.

11 A method as claimed in any of claims 2 to 10, wherein the processing depth limit is defined based on information of the geometry of the object.

12 A method as claimed in any preceding claim, wherein in a final working cycle the path of relative movement between the tool and the object is based solely on the second information.

13 A method as claimed in any preceding claim, wherein the second information comprises at least one of: information of the final geometry of the object; information of the initial geometry of the workpiece for the object; information of the machining parameters; information that associates with the material to be processed; information of the tool.

14 A method as claimed in claim 6 or any claim appended thereto, wherein at least one of the processing parameters is varied such that a substantially similar amount of material is removed from the object regardless the processing depth of the tool.

A method as claimed in any preceding claim, wherein the tool holder assembly is moved by means of a robot.

16 A method as claimed in any preceding claim, wherein the processing of the object comprises one of: deburring; grinding; milling; tooling; reaming; boring; cutting; polishing; finishing; brushing; spraying.

17 A system for processing an object, comprising:

a tool for processing the object; actuator apparatus for providing a relative movement between the tool and the object; a tool holder assembly for holding the tool; a non-contacting sensor for providing first information regarding relative position between the surface of the object and the tool; a source of second information that associates with the object; and a controller that is adapted to process said first information together with said second information for generation of a path of relative movement between the tool and the object for processing of the object by the tool along said path of relative movement.

18 A system as claimed in claim 17, wherein the controller is adapted to monitor if a processing depth limit is to be exceeded, the limit being defined based on the second information.

19 A system as claimed in claim 18, wherein the controller is arranged to control the movement the tool such that the tool processes the object in a relatively uniform depth relative to the surface of the object throughout a working cycle of the tool based on the first information unless the monitoring indicates that the processing depth limit is to be exceeded.

20 A system as claimed in claim 19, wherein the tool is arranged to process the object based on the second information to a depth that does not exceed the processing depth limit in positions where the limit is indicated to be exceeded.

21 A system as claimed in any of claims 17 to 20, wherein the path of relative movement is positioned in a region that is between a path of movement that would be generated based solely on the first information and the path of movement that would be generated based solely on the second information.

22 A system as claimed in any of claims 17 to 21, wherein the tool is adapted to remove material from the object.

23 A system as claimed in any of claims 17 to 22, wherein the tool holder assembly comprises a spindle apparatus for providing rotation of the tool.

24 A system as claimed in claim 23, wherein the spindle apparatus consists of a high speed spindle.

A system as claimed in any of claims 17 to 21, wherein the tool is adapted to spray material on the object.

26 A system as claimed in any of claims 17 to 25, wherein the actuator apparatus comprises at least one robot adapted to move the tool relative to the object.

27 A system as claimed in any of claims 17 to 26, wherein the actuator apparatus is movable relative to the object.

28 A system as claimed in claim 27, wherein the actuator apparatus is mounted on tracks.

29 A system as claimed in any of claims 17 to 28, wherein the tool holder assembly is provided with automatic tool change function.

A system as claimed in claim 29, wherein the automatic tool change function is provided by an automatic tool holder of the spindle apparatus, said automatic tool holder being adapted to automatically clamp and/or release a rotating tool.

31 A system as claimed in claim 29, wherein the automatic tool change function is provided by an arrangement enabling an automatic change of the tool holder assembly.

32 A system as claimed in any of claims 17 to 32, comprising machine vision means for producing information of the object based on an image of the object.