NL2013790B1 - Robot for gripping and manipulating of one or more objects. - Google Patents

Abstract

The present invention relates generally to the field of robots for gripping and manipulating objects. More specifically, to the field of linear robots arranged for gripping and manipulating food related products or other products requiring high hygiene standards. The robot according to the invention comprises a gripper assembly, a stationary basis comprising a rectangular framework having four sides which define a working envelope, a first axis extending between a first and a second opposite side of the rectangular framework for movement of the gripper assembly in a first direction, a second axis extending between a third and a fourth opposite side of the rectangular framework and perpendicular to the first axis, at least two stationary actuators arranged on at least one corners of the rectangular framework, a first and a second drive belt arranged on the first and second side of the rectangular framework respectively, a third and a fourth drive belt arranged on the third and fourth side of the rectangular framework respectively, wherein the second axis is fixed between the drive belts, and wherein at least one of the third and fourth drive belt is actuated by one of the stationary actuators, and wherein said gripper assembly is provided at the intersection of said first and second axis for gripping said one or more objects.

Description

Title: Robot for gripping and manipulating of one or more objects.

Description

Technical Field

The present invention relates generally to the field of robots for gripping and manipulating objects. More specifically, to the field of linear robots arranged for gripping and manipulating food related products or other products requiring high hygiene standards.

Background of the Invention

The first robots were used to perform simple tasks as pick and place. If such robots are used in an industrial environment these robots are known as industrial robots, such in comparison with for example robotised vacuum cleaners and grass mowers, or personal robots that look like a person or animal, such as a dog. In relation to the invention robots are to be interpreted as industrial robots, not as the personal robots, vacuum cleaners or the like. However, industrial robots are not to be interpreted to narrow. Also robots to pick and place or manipulate/process food are considered industrial robots.

Industrial robots replaced humans in the process of automation by performing simple monotonous, repetitive, heavy and/or dangerous tasks. During time industrial robots have evolved and are capable of performing more complex tasks. Not only the use of imaging sensors have helped to perform such complex tasks, since by having an image sensor the robot can act more interactive, also the increased complexity in movement added to the capability of performing these complex tasks.

Nowadays robots are capable of performing tasks such as welding, grinding and assembling. In the food industry for example robots are used more and more to replace humans in the processing of food. From hygiene point of view robots have advantages, but also disadvantages. For example simple linear transport from one place to another can be performed by a conveyor belt, such at high speed, high throughput at high weight. Robots however can also be comprised out of many individual components, some of which often move. These components need high microbe resistance and should be manufactured in such a way that they can resist cleaning by chemicals, steam, and/or pressure washer.

Often these robots used in the food industry need to pick a single product and place it at a certain position, for example from a conveyer belt to a box for packaging the products. The workplace of these robots needs to be large enough to for the robot to reach both the conveyer belt as well as the box. Such a workplace in which the robot is capable of manipulating the products is known as a working envelope.

It is known to use both scara robots and delta robots for such tasks. Scara robots stands for Selective Compliance Assembly Robot Arm. Scara robots have a parallel-axis joint layout wherein the arm is slightly compliant in the X-Y direction but rigid in the Z direction. This has advantages in all kinds of assembly tasks. The scara robot can also be distinguished by the jointed two-link arm layout which is similar to a human arm. This allows the arm to extend into confined areas and then retract. Since scara robots are mounted on a single pedestal is requires a small footprint, hence the ground space needed to install the robot on. However, scara robots also have disadvantages. They are more expensive than most other robots and the control of the robot is far more complex than for example a linear Cartesian robot since the movement of the arms creates circular movement of the arm attached thereto. Therefor control of the scara robot requires inverse kinematics for linear interpolated moves. Scara robots are known in designs with three axis up to six axis. With a six axis design there are six degrees of freedom that not only can move up and down, left and right but also rotate around each of the X-Y and Z axis. A drawback and result of the increase of degrees of freedom, hence, the axis, is the increase in complexity and weight of such a robot.

An alternative to the scara robot is the delta robot, sometimes also referred to as a spider robot due to the layout of the arms. The delta robot is a parallel robot that uses several computer controlled parallel kinematic chains to support a single platform, i.e. gripper. In particular is comprises three arms connected to universal joints at the base of the robot. The robot is mounted above a workspace. The footprint is therefor equal to the working envelope and not in comparison with the scara robot located outside the working envelope. The delta robot is also large, complex, expensive and rather complex to control in comparison with a linear Cartesian robot.

Moreover, both scara robots and delta robots have the disadvantage that for example a linear movement of the gripper can only be achieved by movement of multiple arms. If the movement is to be performed at high speed the acceleration induces high forces, which means that the components need to be manufactured from low weight materials to contain the moment of inertia. Such low weight material are either not the most strong materials or are very expensive.

Furthermore, when using high speed robots and/or heavy duty robots, almost all of these robots are placed in a structural cage. This cage also functions as a safety measure. Most robots and especially delta robots need a case to stabilize the robot and prevent displacement of the robot, due to the high forces upon movement for example. When applied in the food industry these cages have a negative impact on hygiene since they comprise all kinds of edges, corners, recesses, slits, groves, etc. in which bacteria grow. Cleaning these cages is cumbersome since they are large, heavy, closed structures that can’t be moved in an easy manner. If for example a robot is defect, its tasks can’t simply be performed by deploying temporary personnel.

As such, there is a need for an improved robot that is arranged to perform tasks such as the processing of food. Hence, it is an object of the present invention to provide for a robot that is arranged to, amongst other, process food which overcomes at least some of the above identified disadvantages of known robots. More in particular, it is an object of the present invention to provide for a robot arranged for process food at a high hygiene standard that is more simple in construction, lower in costs and easier to control.

Summary of the invention

In a first aspect of the invention there is provided a robot for gripping and manipulating of one or more objects, which robot comprises: a gripper assembly for gripping and manipulating the one or more objects; a stationary basis comprising a rectangular framework having four sides which define a working envelope and in which working envelope the gripper is arranged for gripping and manipulating the one or more objects; a first axis extending between a first and a second opposite side of the rectangular framework for movement of the gripper assembly in a first direction; a second axis extending between a third and a fourth opposite side of the rectangular framework and perpendicular to the first axis, for movement of the gripper assembly in a second direction; at least two stationary actuators arranged on at least one corner of the rectangular framework and arranged for movement of the first and second axis in the first and second direction; a first and a second drive belt arranged on the first and second side of the rectangular framework respectively, wherein the first axis is fixed between the drive belts and arranged for movement in the first direction, and wherein at least one of the first and second drive belt is actuated by one of the stationary actuators; a third and a fourth drive belt arranged on the third and fourth side of the rectangular framework respectively, wherein the second axis is fixed between the drive belts and arranged for movement in the second direction, and wherein at least one of the third and fourth drive belt is actuated by one of the stationary actuators, and wherein said gripper assembly is provided at the intersection of said first and second axis for gripping said one or more objects.

As discussed, robots that are used in the food industry and arranged for pick-and-place tasks for example, are usually delta robots, three-axis scara robots or six-axis robots. Not only do these known robots have complex architectures, hence comprise many individual parts which have a negative effect on hygiene, they are also heavy, large, have a large footprint

In a first example there provided a robot that is arranged for the food industry and able to grip and manipulate objects such a food product, which robot is more simple in construction. It is comprises a gripper assembly for gripping and manipulating one or more objects, i.e. food products such as sausages or the like. Such grippers are known and can for example be comprised out of multiple small arms that can grab the object, or hold the object by suction or creating a vacuum.

The robot comprises a stationary basis which comprises a framework, in particular it is a rectangular framework, and more in particular a square shaped framework. The framework has four sides. These sides do not only determine the outer circumference of the robot, it also defines the working envelope thereof. With the working envelope the area is meant in which the objects can be reached, hence gripped and manipulated (moved) by the gripper assembly.

The robot is a linear robot arranged to grip and manipulate within the X, Y, Z domain. Therefor is comprises, in a first example, a first and second axis such that movement within the X and Y domain can be performed. These first and second axis are perpendicular to each other. The first axis extends between two opposite sides of the framework and the second axis extends between the other two opposite sides of the framework.

The movement of the first and second axis is facilitated by actuators, e.g. stepper motors. These actuators are positioned at one or more corners of the framework. The robot comprises at least two of these actuators in order to facilitate the X and Y movement, hence first and second movement of the gripper assembly.

The movement in the X and Y direction is made possible by using drive belts. The axis for movement in the X direction is attached at its free ends to two drive belts that are provided at two opposite sides of the framework. The axis for movement in the Y direction is attached at its free ends to the other two drive belts at the other remaining opposite sides of the framework.

The actuators drive the drive belts in order to move the first and second axis. Within the intersection of the first and second axis the axis the gripper assembly is present. Powering the first stationary actuator will move the first axis in the first, X, direction, towards a predetermined X location, powering the second stationary actuator will move the second axis in the second, Y, direction toward a predetermined Y location, and by powering the gripper assembly objects can be gripped, hence picked-up, at that X, Y position. After picking up, the first and second actuators can be powered again to move the gripper assembly and hence the gripped object towards a predetermined X’, Y’ position accordingly.

Such a robot has several advantages. In comparison with the above described known robots, a robot according to a first example can be controlled by Cartesian coordinates. Not only is it simpler than circular movement positioning, a robot according to the invention, due to its construction only has to move the Z movement motor, i.e. gripper assembly upon movement in the X and Y direction. Conventional robots either move all axis motors upon movement in a first direction, or move both the axis motors of the second and third direction upon movement in the first direction. In other words, when according to a Cartesian coordinate a product has to be moved from (0,0,0) to (1,0,0) the motors for the Y and Z direction are moved upon movement of 1 unit in the X direction. With a robot according to the first example, such is not the case. This lowers the weight to be moved by the actuators, hence, actuators with lower power consumption requirements can be utilised.

Another major advantage of the robot according to the first example is that such a robot has few moving parts and is simple in construction. By using drive belts in stead of gearing there is a lower chance of particles getting stuck between the drive belt than the gearing parts. This improves hygiene and hence enables processing of objects that require high hygiene standards such as food processing.

Moreover, a robot according to the first example is relatively light in comparison with known robots. It can even be mounted on a movable framework. The robot on such a framework can hence be moved in and out of the production/processing line for example by use of a docking station. If the robot needs to be moved, due to a failure, test, or scheduled maintenance for example, it can simply be disconnected from the docking station and moved out of the way. Known robots can’t be moved, or require a substantial amount of work and specialised materials before the robot can be moved.

With a robot according to the first example there are few forces on the framework. The kinematics of the robot of the first example are improved in view of known robots. Due to sliding of the gripper assembly and amongst others, the low weight to be moved, the forces on the framework are small. It thus does not require known prior art large and heavy structures/frameworks that can’t be moved in an easy manner,

In an example the robot further comprises a third axis arranged in the working envelope and perpendicular to the first and second axis, for movement of the gripper in a third direction.

In the first example the robot comprises a first and second axis for movement in the X and Y direction, i.e. the first and second direction. The gripper assembly can pick up objects for example by suction and release of the object. However, the movement in the Z direction, i.e. the third direction is then limited to the displacement of the object under the influence of the suction, hence the suction power of the gripper. By using a further, third axis the range of movement in the Z direction increases by the amount of freedom of movement of the third axis. Hence, the robot can in a simple embodiment function solely with a first and second axis, but will be in a more practical embodiment be comprised of a third axis.

In an example the third axis is arranged to be detached from the first and second axis. With detached is meant that the third axis and thus the motor for the movement of the gripper end part that grips the object, is not rigidly fixed to the robot. The third axis, and thus the gripper assembly, can be detached from the robot at any moment in time. This has the advantage that change of gripper configuration can be performed without dissembling the robot. Simply changing between a suction unit and a gripper can be performed by replacing the whole gripper assembly.

In an example the third axis is arranged on the intersection of the first and second axis and arranged for sliding over the first and second axis. The gripper assembly can be attached in different ways to the first and second axis. The first and second axis form an intersection. At the intersection the third axis, hence the gripper assembly, is attached in such a way that it can move in first and second direction in a passive manner. In the example, there is no need for active, i.e. powered movement by an actuator. The gripper assembly is configured to slide over the fist and second axis.

In an example both the first and second axis are comprised of at least two rods. The axes can be formed in many ways. In an example each axis is comprised of two horizontal rods. These can be positioned next to each other, i.e. in the X-Y domain or above each other, i.e. in the Z domain. In a practical embodiment the two rods will be disposed parallel to each other in the X-Y domain such that they define a space in between. In that space the gripper assembly, i.e. third axis, can move, in particular slide, in the first direction. The second axis is also comprises of two parallel rods disposed next to each other in the X-Y domain such that they also define a space in between. In that second space, which can but does not have to have the same dimension of the space defined by the first axis, the gripper assembly can move, in particular slide, in the second direction. In other words both axes, i.e. the first and second axis, define a space. In the intersection of these spaces the gripper assembly is disposed in such a way that movement in X and Y direction is possible.

Accordingly the rods can also be disposed above each other, i.e. in the Z domain. In such an embodiment the gripper assembly is arranged to confine or lock the rods. Contrary, in the embodiment wherein the rods are disposed next to each other, the gripper is disposed in between the two rods.

In an example both the first and second axis are comprised of at least four rods. When the two rods per axis are disposed next to each other, the stability of the gripper assembly is further increased when four rods per axis are used. Then not only the rods are next to each other, they are also above each other.

This creates a three dimensional space in which the gripper assembly can be placed in a stable manner.

In an example the gripper assembly comprises a cuboid housing, and in particular a cube shaped housing, the housing comprising a square shaped base plate having an outer diameter larger than the housing and wherein the diameter of the housing has an outer diameter such that it can be contained inside the intersection of four rods of the first axis and the four axis of the second axis.

In an example the gripper assembly can further comprise a base plate that is attached to, or forms the top surface the housing. When the base plate is larger in diameter then the housing, and the housing fits within the three dimensional space defined by the intersection of the rods, the base plate can rest on the rods in such a way that the housing is contained in the space between the rods with low friction therewith. The base plate prevents the housing from falling through the space and hence carriers the housing. The gripper assembly, i.e. the housing is then arranged to slide with low frictional force over the rods in the first and second, i.e. X and Y direction. Such subsequently or simultaneous.

In an example the robot comprises at least two stationary actuators, and more in particular at least four stationary actuators, arranged on all corners of the rectangular framework.

The actuators are stationary which means that they, contrary to actuators from known robots, are fixed to the framework. The only actuator that is displaceable and will be moved is the actuator of the gripper assembly, which enables the movement of the third axis in the thirds, i.e. Z direction. The actuators are positioned at the corners of the framework and drive the drive belts. In a most simple embodiment the framework can be provided with two stationary actuators, one for the fist and one for the second axis movement. These actuators are both provided with cooperating rollers such that the drive belt is contained between a roller at one end and the actuator at the other end. In such a way both the first and second axis are attached to a drive belt at one side of the framework wherein one of the rollers holding the drive belt in place is an actuator. On the other side however the drive belt can be considered only a belt since it is not actively driven, due to absence of an actuator.

In a more practical embodiment the robot will be provided with at least four actuator, one for each drive belt. The drive belts however can be biased with respect to each other, for example due to slipping of the drive belt over de actuator. In an example each of the drive belts comprises calibration position means and each side of the rectangular framework comprises a sensor for detecting the calibration position means, and wherein stationary actuators on opposite sides of the rectangular framework are arranged to be calibrated in respect of each other on the basis of the sensors.

By calibrating opposite drive belts, i.e. the drive belts in between which a single axis is disposed, such biases can be removed. In an example the drive belt can be provided with a marker, visual or electro magnetic for example, that can be detected by a sensor. The sensor then detects if the drive belt is at its calibration position or not. If not, the actuator can be powered to drive the belt until its calibration position is reached. If both opposite corresponding drive belts for a single axis are calibrated the axis is ready for use. The same principle applies to the calibration of the drive belts for the second axis.

In an example each side of the rectangular framework comprises at least one tension roll for keeping the drive belt under tension. To keep the drive belts under enough tension such that slipping of the drive belt over the actuator is prevented, the framework can be provided with tension rolls. These tension rolls can be disposed at the corners of the framework near the actuator, or can be placed in the middle of the drive belt. Thus the tension rolls can either function as counter part for the actuator, between which tension roll and actuator the drive belt is driven, or there can be an additional tension roll or multiple additional tension roll that are placed on the exterior side of the drive belt and press against it to increase the tension. With such an additional tension roll the tension of the drive belt can be configured as desired and for example be configured in accordance with the length of the drive belt and/or the horizontal or vertical positioning of the framework. With either which configuration the tension rolls have the advantage that there is less tolerance in the lateral direction of the drive belt.

The tension of the drive belts can be such that, in an example, the drive belts of the longest axis, e.g. the X axis, is relative low. The gripper assembly can then still be positioned vary accurate if the tension of the drive belts of the other, shortest, e.g. the Y axis, is higher.

In a further example the robot can be provided with additional guiding means for guiding the drive belts if these are relatively long. With large size frameworks the drive belts are also long. When the tension on the drive belt is not very high, they tend to become slack/saggy. As an alternative to increasing the tension of the belts, the belts can be provided with additional guiding means for guiding the drive belts. These guiding means can be implemented as guiding wheel that (partially) carriers the weight of the drive belt. The longer the drive belt, the more guiding wheels can be used.

In an example at least the stationary actuators are contained inside a housing arranged on the corners of the rectangular framework, and wherein the housing in particular comprises an overpressure. When working with food the standards for hygiene are high. By containing the actuators and/or other moving parts or parts susceptible to contamination in a housing the risk of contamination is lowered. In particular, the housing can be provided with an overpressure to ensure that no particles, i.e. dust or food, enter the housing.

In an second aspect there is provided a gripper assembly arranged for a robot according to any of the previous descriptions.

In an third aspect there is proved an optical detection unit arranged for being mounted on the rectangular framework of a robot according to any of the previous descriptions, wherein the optical detection unit is arranged for detecting movement of a person or object in the direction of the robot for providing a signal towards the actuators of the robot to cause one or more of lowering the speed of driving the drive belts or stop driving the drive belts.

The robot can work autonomously on the basis of programmed instructions. For example, to pickup each second an object at Cartesian coordinate position (1,1,1) and place the object at (2,2,1). The robot can however also work more interactively by a feedback signal provided by an imaging device such as a camera for example. The camera detects object when present within a predefined area of the working envelope and then triggers the gripper to pick the object and move it to a predefined position for example. When no objects are present, the gripper remains in position, waiting for the next object to enter the predefined area.

In order to increase security of the robot, the robot can be provided with means to trigger an alarm function of the robot and shut down its power. This should for example be performed when a person or limb of a person is to close to the robot. In an example of a third aspect there is provided an optical detection unit such as a camera which can detect whether a person, or limb of a person, or any other unwanted object enters a predefined area. The area can for example be defined as an area of 50 cm around the circumference of the robot. When someone approaches the robot and is less than 50 cm away from the framework of the robot, a signal is transmitted to an emergency stop of the robot, bringing it to a hold. That way the robot can operate in an area in which persons can be present as well and the robot does not have to be contained in a cage.

In a further example there can also be two areas, one closest to the robots framework and one further away. When something moves into the area which is further away, the robot can be provided with a signal to lower its speed to a low risk level. Only when subsequently the second closest area is reached, the robot is stopped. In that way the first lowering of the speed can also be considered a warning.

The above-mentioned and other features and advantages of the invention are illustrated in the following description with reference to the enclosed drawings which are provided by way of illustration only and which are not limitative to the present invention.

Brief description of the drawings

Figure 1 shows, in an illustrative manner, an example of a known delta robot configuration;

Figure 2 shows, in an illustrative manner, an example of a known three axis scara robot configuration;

Figure 3 shows, in an illustrative manner, an example of a known six axis scara robot configuration;

Figure 4 shows from a perspective point of view, an example of the robot according to a first aspect of the invention;

Figures 4A and 4B show details of an example of the robot according to a first aspect of the invention;

Figure 5 shows from a top side, an example of the robot according to a first aspect of the invention;

Figures 6a-6d show from different perspective views a guiding means according to an example of the invention;

Figure 7 shows an example of pedestal framework according to the invention;

Figure 8 shows an implementation of an example of a robot according to a first aspect of the invention.

Detailed description

In Fig. 1 a delta robot 10 is shown as known from the prior art. The robot includes a gripper assembly 76 to which a gripper unit of another type of tool can be attached and controlled. Each arm 12 includes an upper arm section 16 and a lower arm section 18 including pairs of tubes 20. The tubes need to be made from strong material in order to resist the high forces thereupon. Each arm is pivotally connected to the associated upper arm section 16 and the tool receiver 76. The upper arm section 16 are pivotally supported at the robot base 14 and offset by 120 degrees to each other. A main drive unit 22 which includes a motor is associated with each upper arm section 16 to pivot the upper arm section 16. The drives 22 are arranged such that they are installed without housing, resulting in high contamination risks.

The three drives 22 are arranged along a circle and are each spaced apart from one another by 120 degrees. The axes of rotation of the drives 22 are parallel to the respective tangents of the circle at an offset of 120 degrees. The robot further has a base plate 24 to whose lower side three plate shaped bearing seats 26 for the drives are attached. The robot can be installed to a suitable carrier construction or framework, also known as a cell structure, with the help of the robot base 14 and in particular the base plate 24. Pivoting of the tubes 20 in view of the lower arm section 18 and upper arm section 16 takes place by ball joints arranged on oppositely disposed sides of the upper arm section 16. A data robot can also be referred to as a spider robot due to the layout of the arms. The footprint of the delta robot according to Fig. 1 is equal to the working envelope and not in comparison with for example a scara robot located outside the working envelope. The delta robot is large, heavy, complex, expensive and rather complex to control due in comparison with a linear Cartesian robot.

In Fig. 2 a scara robot 30 is shown. The robot has a base construction 32, i.e. the framework that rests on a pedestal 31. To the base construction a first axis or arm 34 is attached, driven by drive 33. A second axis or arm 36 is pilotable around the first axis by a drive 35. The pivoting construction of the both axes enables double circular movement of the third axis 37 attached at end of the second axis or arm 36. By this construction a two dimensional movement can be realised. Extending the tool tip 38, i.e. the gripper assembly to which a gripper or suction unit is attached, enables movement in the third direction, enabling three dimensional movement.

Scara robot is an acronym for Selective Compliance Assembly Robot Arm. Scara robots have parallel-axis joint layout wherein the arm is slightly compliant in the X-Y direction but rigid in the Z direction. This has advantages in all kinds of assembly tasks. The scara robot can also be distinguished by the jointed two-link arm layout which is similar to a human arm. This allows the arm to extend into confined areas and then retract. Since scara robots are mounted on a single pedestal is requires a small footprint, hence the ground space needed to install the robot on. Control of the scara robot requires inverse kinematics for linear interpolated moves. Inverse kinematics of the scara robot prevent the robot from linear movement. Moreover, the scara robot requires additional space outside the working envelope, i.e. the area in which the robot can operate (pick, place, manipulate, etc.).

Fig. 3 shows a known six axis (scara) robot 40 which has six degrees of freedom. The base structure 42 of such a known robot 40 is mounted to the floor for example by a pedestal mounting plate 41. It first motor 43 enables rotation of the rest of the arms. That way the first 44 and second arm 46 can be rotated around the lateral axis of the robot. Another motor 45 enables rotation of the second axis or arm 46. The gripper assembly 47 is attached to the end of the second arm 46 and can be provided with a suction unit or gripper (not shown) at a connection interface 48.

Fig. 4 shows an example of a robot 50 according to the present invention. The robot is disposed on a rectangular framework which can also be square shaped. The framework comprises at least four feet 51 and multiple crossbars 52a, 52b attached in between the feet to increase stability. To the feet transport wheels can be attached, for example made from a plastic material. In that way the robot can easily be moved in and out of a production location or production line.

The framework has four sides which define a working envelope of the robot. The robot 50 has the advantage that it does not require additional space beyond the working envelope. The gripper assembly 57 is disposed within the working envelope to pick, place and manipulate objects such as food products.

On each side of the framework a drive belt 54a, 54b, etc. is disposed. These drive belts are attached to an actuator 55a at one end, and a roller 56a on the other end of the same side of the framework. Accordingly, each side is provided with a drive belt. The framework can comprise either two actuators, one for actuating a drive belt on one side of the framework, and the other for actuating a drive belt perpendicular thereto. However, the robot will be more efficient if at least four actuators are used, such that each drive belt is actively driven in stead of following the movement of the opposite drive belt. Alternatively, each side of each drive belt can be provided with an actuator. Then each drive belt is driven by two actuators. An example of an actuator than can be used is an electromotor. These motors can be stepper motors which have a high rate of accuracy such that the resolution is high, giving high amounts of distinctive position in both the X and Y direction.

The actuators are attached to the framework on the corners thereof and can be contained in a housing 53 which is for example air tight or provided with an over pressure such that small dust or food particles are kept out.

The robot can furthermore be provided with an additional detection system 59. This system, i.e. a visual camera, is placed on top of the robot such that it can observe all movement thereof. The visual area of the camera is at least the size of the working envelope of the robot, thus the area in between the sides of the framework.

The camera 59 not only detects movement of the gripper within the X-Y domain of the working envelope, it can also be arranged to detect objects other than the ones belonging to the robot, hence the objects to be manipulated such as the food products. These objects can than be located in a precise manner, such data is used to feed the control system of the gripper 57, which moves towards that coordinate and picks up the object for further handling.

Since robots are automated machines there is a potential risk that for example an unwanted object enters the working envelope of the robot, an object other than the objects to be manipulated (for example a limb of an operator). In that situation the robot should halt al movement such that hazardous situations do not occur. Most conventional robots are equipped with a laser detection system or an optical switch. When an object is in the light beam of the laser or optical switch, the robot is fed with an emergency halt signal by which the robot is brought to a halt.

Such lasers however are limited to detecting objects only in the line of sight, hence with the beam. If the potential area by which someone or something can enter the working envelope of the robot, plural lasers or optical switches should be used. This makes such a system complex, and not only has a negative influence on the reliability of the system, it is also of high costs. An alternative is to embed the robot within a cage construction such that physical contact is prevented.

With a camera 39 according to an example of the invention however the whole area of the working envelope and the areas around it is imaged. That image is constantly monitored. The camera can be programmed in such a way that the borders of the working envelope are known. In that way the camera can detect objects when they enter the working envelope, and on the basis thereof trigger the emergency signal to bring the robot to a halt. Alternatively, the camera can also detect object not to enter the working envelope but to enter a predetermined area around it. That way the robot can already be brought to a halt when the is an object in a no-go zone. The robot is than stopped even before the object enters the hazardous working envelope.

In a more advanced embodiment the camera 59 can be programmed to have multiple zones. A first zone, being the working envelope, is a zone which no object should enter, a second zone can be the zone directly around it and a third zone in the circumference of the second zone. If an object enters the third zone, a warning signal can be produced such as an audio signal or an emergency light to indicate that someone or something is in a forbidden area. The robot can be controlled in such a way that it still functions however at lower speed such that if an object should reach the working envelope, the damage will be minimal. If the object however enters the second zone, the robot can be brought to a halt, such that there is no risk of contact with moving parts of the robot within the working envelope. In that way the robot can operate at multiple levels, a full operation mode when no unwanted object is within the defined zones, a low speed operation mode when something or someone is within a first hazardous zone, and a stop mode when the system is brought to a halt when someone or something is within the no-go zone.

When compared to conventional known robots the robot according to an example of the invention operates at lower power. Due to the capabilities of the robot it can be considered a heavy industry robot. However, when looking at power requirements and safety levels, the robot can be considered a small and medium enterprise robot. The robot, due to its design, can even operate at voltage levels as low as 40 Volt and up to 96 Volts, whereas comparable prior art robots require three-phase electric power. This is a result of the design of the robot. The actuators of the robot do not need to move heavy parts but only drive a light weight drive belt. Moreover, conventional robots need to move the actuator for both the Z and Y movement upon movement within the X domain. The robot according to the invention only moves the actuator of the Z domain upon movement of the X and Y domain and thus can operate at lower power, hence, lower voltage levels.

Fig. 4A is a close up of the gripper assembly 57 and the layout of the rods that form the X and Y axis. As can be a first axis is attached to the a drive belt 54a. The first axis is comprised out of 4 individual rods 63a, 63b, 63c, 63d which are placed in a cuboid configuration. As such there is a space defined in between the rods. The space between the rods is such that it can fit a rectangular shaped gripper assembly 57 as indicated in the figure. That way the gripper assembly 57 can freely move in the first, X, direction between the rods 63a-63d. In the same way an axis is formed on the other drive belt 34b. That second axis is also comprised out of 4 individual rods 62a-62d which are also placed in a cuboid configuration. As such it also creates a space in between the rods in which the rectangular shaped gripper assembly 57 can freely move in the second, Y, direction between the parallel rods 62a-62d. In the intersection of both sets of rods there is formed a cube shaped space that precisely fits the gripper assembly 57 and in particular the housing 61 of the gripper assembly 57. The gripper assembly 57 floats or hovers within the rods of the both axes and is only held in place under its own weight. To prevent the gripper assembly from falling through the rod configuration the gripper is equipped with a base plate 61 that is larger than the space between the rods. That way the gripper housing 60 is kept at its place and the weight of the gripper assembly 57 is carried by the base plate 61 on the top rods of the first and second axes. The gripper assembly is arranged to freely, and with very low friction move within the first and second direction.

The fact that the gripper assembly, for example comprising a gripper based on suction via a vacuum hose 59, is not rigidly attached to the robot and can be pulled out of the rods in a simple manner makes it easy to clean the robot. In the food industry the processing equipment should be cleaned on regular basis. So with the robots. For conventional robots that can be a challenge. Scara robots and delta robots are simply not designed to be cleaned with for example aggressive chemicals and/or a pressure washer. Due to the simple construction of the robot according to the invention, the gripper assembly can be pulled out without having to dismantle the robot. What remains is only a framework, for example made from stainless steel, drive belts, for example made from FDA approved plastics and actuators that are housed in an air and water tight housing. Hence, once the gripper assembly is removed the robot can be cleaned very easily, for example by a pressure washer.

In Fig. 4B a close up of the drive belt 54a and actuator, i.e. motor 56a is shown. As can be seen, only the roller of the motor 56a is visible. The powered parts of the motor are contained in a housing 53 underneath. The housing forms part of the framework. The drive belts can as indicated above, be made from FDA approved materials such as an FDA approved plastic. In an embodiment the drive belt can have a height of around 100 mm which results in a Z axis displacement of around 200 mm. However, the invention is not limited to drive belts which such heights. By increasing the height of the drive belts up to 1000 mm the Z axis displacement can be as high as 2000 mm and is that strong that it can move heavy loads/objects.

In Fig. 5 a top side view of the robot is shown. The framework is rectangular by shape. It can however also be square shaped. Each side of the framework is provided with a drive belt. In between opposite sides of the drive belts the first and second axis are present and formed by four individual rods 63a-63d, 62a-62d. Above the robot a camera system 59 is mounted to observe the working envelope and spaces around it.

The hovering gripper assembly 57 operates best under the lowest friction of the individual rods. When the rods are not perfectly perpendicular to each other the friction of the gripper assembly increases. In order to prevent such a bias in rod configuration the positioning of the drive belt is relevant. When the drive belts are aligned, the angle between both sets of rods is 90 degrees. The drive belts however are not rigid and can be made from a plastic material. The larger the drive belt, the higher the risk of slipping over the motors. When such slipping occurs, the rod are not aligned any more. That can be resolved by a calibration system that can be implemented at multiple levels.

The first level is at the motors. To determine the position of the motor, the framework is provided with calibration means, for example visual calibration indicators 65a, 65b provided on each corner of the framework. The second level is at the gripper assembly. To determine the position of the gripper the gripper assembly 57 is provided with calibration means 66a-66d on all corners of the gripper housing. The camera can detect all these calibration indicators 65a, 65b, 65... and 66a, 66b, 66c, 66d and on the basis of an programmed algorithm can calibrate at certain moments in time, or on a continuous basis. In that way the robot is always able to operate at the right pick coordinates and make sure the drive belts are aligned correctly.

An alternative to the calibration means as described above is to use an end stop. As indicated, the robot functions best when the angle between the first and second axis is exactly 90 degrees. When the robot is installed, the drive belts can be attached in such a way that both axis form a 90 degrees angle. Than however, can be challenging. Moreover, is does not prevent a bias in the 90 degrees angle when the robot is up and running and for example one of a drive belt slips. By using an end stop for example at the end of the framework, the axis and mounting plate of the axis on the drive belt will not be able to go beyond that end stop. The motor will try to move the axis but cannot move it beyond the end stop. That results in the high current drawn from the motor. That way the calibration means will known the drive belt is at its calibration position. That process is executed for each of the drive belts until all drive belts are in their calibration position and the robot can start its operations perfectly calibrated. By this process of calibration not only a perfectly calibrated robot is obtained, it also assures that there are no unwanted objects within the working envelope because that would also result in an increase in current drawn from the motor. A robot according to the invention is scalable to large extents. For example a plurality of robots can be placed over an assembly line or conveyer belt to perform sequential tasks. Each robot can be designed in accordance with the tasks to be performed and the position at the line or conveyer belt, such simply by increasing or decreasing its dimensions. Moreover, by mounting the robot to a framework construction such that is can be hoisted, it can replace any embodiment of a six axis robot. Due to its jointed arm construction and single pedestal mount these six axis robots have a limited working envelope. A very large working envelope would require large arm constructions with height weight to be carried by the single pedestal that would simply not be able to move fast anymore. The robot according to the present invention does not have these limitation and can be employed in all dimensions.

Fig. 6a-6d show guiding means from different perspectives. The guiding means are attached to one or more of the drive belt of the robot when positioned vertically, as for example shown in Fig. 8. The guiding means can also be attached to one or more of the drive belts when the belts are long, for example longer than 2 meters. The guiding means 70 have two double plates 72a, 72b and 73a, 73b. One side of the drive belt is placed in between plates 72a and 73a and the other side of the drive belt is placed in between the other plates 72b, 73b. One of the set of plates, for example the inner plates 72a and 72b can be provided with a tooth structure in accordance with the tooth structure of the drive belt, such that the plate and hence guiding means can not slip over the drive belt. To fix the plates to the drive belt, two through holes 74 are provided in which a bolt can fixed. The guiding means have two extending guide members 75a and 75b which have two diablo wheels 76a, 76b between which the cross bar 52a of the framework can be incorporated. Due to the design of these wheels the guiding means can easily slide over the cross bar 52a of the framework while supporting the drive belt to which it is attached. The use of guiding means makes it possible to design a robot according to an example of the invention without limitations to the dimensions. For example very large dimensions of up to 8 by 8 meters or even larger is possible.

Fig. 7 shows pedestal framework which can be used to place a robot in perfectly horizontal alignment. Robots are often placed on uneven undergrounds. In the food industry for example such is common and most floors slope at an angle of at least 1% such that water runs towards a place where the water is collected to be processed further. With granite slaughterhouse floors the slope is even higher because many juices and blood are present in such environments and the floors are provided with a coarse grained structure to increase grip.

Since robots and as such, also the robot according to an example of the invention, have to be aligned in a horizontal position, a pedestal framework 80 is provided which makes alignment easy. It comprises a lower triangular framework 82 and a connecting bar 81. Each corner of the lower framework 82 is provided with tubes 83a, 83b, 83c. These tubes are hollow and can receive mating feet units 84a, 84b, 84c. These feed units can be manufactured from plastics that are FDA approved for food industry, such as engineering thermoplastic as polyoxymethylene which is also known as acetal, polyacetal and polyformaldehyde.

The feet have a conical top to make insertion of the feet in the tubes 83a-c easy. The framework of the robot can then be manoeuvred over the feed that are fixed to the floor and when correctly positioned above, the framework can be lowered. Due to the conical tops of the feet these will aligned automatically. And due to the mating shapes, the feet fit tightly in the tubes and the conical top enables water and liquids to run from the feed and the framework 82 such that no dirt can accumulate in the feet or framework.

The bottom parts of the feet have a larger diameter than the inside diameter of the tubes such that these feet are only contained in the tubes up to the lower, enlarged diameter, part such that the tubes rest on the lower part. Since these feet are manufactured from materials that can be worked/machined easily their length can be reduced to the desired length and hence in accordance with the horizontal alignment of the framework. If for example the floor is 1 mm lower at one side 83c of the framework 80 in view of the of other side 83a, 83b, the feet unit 83c can be shortened (sawed off) with 1 mm to overcome the bias by the 1 mm sloped floor.

The feet can be fixed to the floor in such a way that when a robot has to be removed from the site due to regular maintenance for example, the framework can be lifted from its feet. The feet remain in position since they are fixed to the floor. Once the robot maintenance is over, the robot can be moved to the site (next to or over a conveyer belt for example) and be placed on the feet. The robot is then perfectly aligned in horizontal orientation without have to perform calibration steps over and over again.

Fig. 8 shows a situation in which the robot 90 according to the invention can be used. The robot is not only able to operate in a horizontal configuration but also in a vertical configuration as shown here.

Based on the above description, a skilled person my provide modifications and additions to the method and arrangement disclosed, which modifications and additions are all comprised by the scope of the appended claims.

Claims (15)

A robot for gripping and manipulating one or more objects, which robot comprises: - a gripper assembly for gripping and manipulating the one or more objects; - a stationary base comprising a rectangular frame which is provided with four sides, which define a working area and in which working area the gripper is arranged for gripping and manipulating the one or more objects; - a first axis which extends between a first and second opposite side of the rectangular frame for displacing the gripper assembly in a first direction; - a second axis extending between a third and fourth opposite side of the rectangular frame and perpendicular to the first axis, for displacing the gripper assembly in a second direction; - at least two stationary actuators which are arranged on at least one corner of the rectangular frame and are adapted to move the first and second axis in the first and second direction; - a first and second drive belt which are respectively arranged on the first and second side of the rectangular frame, the first shaft being mounted between the drive belts and adapted for displacement in the first direction, wherein at least one of the first and second drive belt is driven by one of the stationary actuators; - a third and fourth drive belt which are respectively arranged on the third and fourth side of the rectangular frame, wherein the second shaft is mounted between the drive belts and is arranged for placement in the second direction, wherein at least one of the third and fourth drive belts is driven by one of the stationary actuators; and wherein the gripper assembly is provided at the intersection of the first and second axis for gripping the one or more objects. A robot for grasping and manipulating one or more objects according to claim 1, wherein the robot further comprises: - a third axis which is arranged in the working area and is perpendicular to the first and second axis, for displacement of the gripper in a third direction. 3. Robot for gripping and manipulating one or more objects according to one of the preceding claims, wherein the third axis is adapted to be detached from the first and second axis. A robot for gripping and manipulating one or more objects according to one of the preceding claims, wherein the third can be arranged at the intersection of the first and second axis and is adapted to slide over the first and second axis. A robot for gripping and manipulating one or more objects according to one of the preceding claims, wherein both the first and second axis comprise at least two rods. A robot for gripping and manipulating one or more objects according to any one of the preceding claims, wherein both the first and second axis comprise at least four rods. A robot for gripping and manipulating one or more objects according to claim 6, wherein the gripper assembly comprises a cuboid housing, and in particular a cuboid housing, the housing comprising a rectangularly shaped base plate which has an outer diameter that is larger than the housing and wherein the diameter of the housing has an outer diameter such that it can be received in the intersection of the four rods of the first axis and the four rods of the second axis A robot for gripping and manipulating one or more objects according to any of the preceding claims, wherein the robot comprises at least two stationary actuators, and more in particular at least four stationary actuators, which are arranged at all corners of the rectangular framework. A robot for grasping and manipulating one or more objects according to claim 8, wherein each of the drive belts comprises a calibration position means and each side of the rectangular frame comprises a sensor for detecting the calibration position means, and wherein stationary actuators on opposite sides of the rectangular framework are arranged to be calibrated relative to each other on the basis of the sensors. A robot for gripping and manipulating one or more objects according to one or more of the preceding claims, wherein each side of the rectangular frame comprises at least one tensioning roller for keeping the drive belt under tension. A robot for gripping and manipulating one or more objects according to any one of the preceding claims, wherein at least the stationary actuators are accommodated in a housing which is arranged at the corners of the rectangular framework, the housing in particular having a overpressure. A gripper assembly adapted for a robot according to any one of the preceding claims. An optical detection unit adapted to be mounted on the rectangular frame of a robot according to any of the preceding claims 1 to 11, wherein the optical detection unit is adapted to detect movement of a person or object in the direction of the robot for providing a signal towards the actuators of the robot to provide at least one or more of reducing the driving speed of the driving belts or stopping the driving of the driving belts. A pedestal frame for a robot according to any of the preceding claims 1 to 11, wherein the pedestal frame comprises a lower rectangular frame that comprises three tubes adapted to receive a corresponding foot. 15. Base frame according to claim 14, wherein the base is provided with a conical top and a thickened bottom, and which base is in particular made of polyoxymethylene.