Industrial robot and method of controlling industrial robot

Abstract

An industrial robot (10) comprising a primary mechanism (14) including a primary link (28b) and a primary actuator (30b) arranged to drive the primary link to move in parallel with a primary plane (24); a secondary mechanism (16) including a first secondary link (34a) and a secondary actuator (36) arranged to drive the first secondary link to rotate relative to the primary link around a first secondary axis (38a); a second secondary link (34b) rotatable relative to the first secondary link around a second secondary axis (38b); and a transmission (40a) interconnecting the primary link and the second secondary link and being configured to transmit a first rotation (84a) of the first secondary link relative to the primary link around the first secondary axis in a first direction to a second rotation (84b) of the second secondary link relative to the first secondary link around the second secondary axis in the first direction.

Description

[0001] INDUSTRIAL ROBOT AND METHOD OF CONTROLLING

[0002] INDUSTRIAL ROBOT

[0003] Technical Field

[0004] The present disclosure generally relates to industrial robots. In particular, an industrial robot comprising a primary link, a first secondary link, a second secondary link and a transmission interconnecting the primary link and the second secondary link, and a method of controlling such industrial robot, are provided.

[0005] Background

[0006] Industrial robots may be used to perform pick and place operations. In a pick and place operation, an object is picked by the robot in a picking region and moved by the robot from the picking region to a placing region where the object is placed. Many pick and place implementations free human workforce previously assigned to the pick and place tasks. One example of a pick and place operation is a singulation operation. In this case, a picking region may comprise a box containing objects. Such box may for example be positioned on a pallet that is transported to and from the picking region by a truck. One example of a placing region is a belt conveyor. Such belt conveyor may move the objects placed thereon by the robot for further processing, such as to a sorting station.

[0007] JP 2021154473 A discloses a working robot comprising a support frame, an upper arm, an elbow part, a forearm and a wrist part. The working robot further comprises a parallel link mechanism including a rod-shaped connecting link whose rear end is swingably connected to a rear link fixed to the elbow part and whose front end is swingably connected to a front link fixed to the wrist part. A spring energizes the front link upward with respect to the rear link at all times. Summary

[0008] One object of the invention is to provide an improved industrial robot.

[0009] A further object of the invention is to provide an improved method of controlling an industrial robot.

[0010] These objects are achieved by the industrial robot according to appended claim 1 and by the method according to appended claim 12.

[0011] The invention is based on the realization that by providing an industrial robot including a horizontally moving primary mechanism, a first secondary link drivingly rotatable relative to the primary mechanism, a second secondary link rotatably coupled to the first secondary link, and a transmission that transmits a forward rotation of the first secondary link relative to the primary mechanism to a forward rotation of the second secondary link relative to the first secondary link, a speed requirement on a secondary actuator for driving the first secondary axis can be reduced, the industrial robot can move towards a picking target or placing target with a small footprint and the industrial robot will have great reachability.

[0012] According to a first aspect, there is provided an industrial robot comprising a primary mechanism including a primary link and at least one primary actuator arranged to drive the primary link to move in parallel with a primary plane; a secondary mechanism including a first secondary link and a secondary actuator arranged to drive the first secondary link to rotate relative to the primary link around a first secondary axis parallel with primary plane; and a second secondary link rotatable relative to the first secondary link around a second secondary axis parallel with the primary plane. The secondary mechanism further comprises a transmission interconnecting the primary link and the second secondary link, the transmission being configured to transmit a first rotation of the first secondary link relative to the primary link around the first secondary axis in a first direction to a second rotation of the second secondary link relative to the first secondary link around the second secondary axis in the first direction. The combination of the primary mechanism and the secondary mechanism comprising the transmission enables new and advantageous kinematics of the industrial robot. For example, the industrial robot enables large vertical movements (or movements transverse to the primary plane) of the second secondary link with relatively small actuations by the secondary actuator. Moreover, the industrial robot has a small footprint and a deep reach, e.g., into a box, for picking or placing an object.

[0013] By virtue of the transmission, both the first and second secondary axes become actuated by the secondary actuator. The transmission may therefore be said to cause a distributed actuation of the first and second secondary links. Moreover, by virtue of the transmission, the second secondary link becomes kinematically bound to the first secondary link. That is, for each rotational position of the first secondary link around the first secondary axis, the transmission kinematically binds the second secondary link to adopt one, and only one, specific position around the second secondary axis.

[0014] Since both the first and second rotations are in the first direction, the first and second rotations may be said to be in the same direction. For example, when the industrial robot is viewed in a direction of the first secondary axis, the transmission may transmit a clockwise rotation of the first secondary link around the first secondary axis to a clockwise rotation of the second secondary link around the second secondary axis.

[0015] The secondary mechanism may include an articulated arm. No dedicated actuator may be provided for driving the second secondary axis. Thus, the second secondary axis may, as such, be considered passive. The primary plane may be oriented arbitrarily in space. However, in some variants, the primary plane is horizontal.

[0016] Since the transmission interconnects the primary link and the second secondary link, the transmission bypasses the first secondary link. The transmission is thereby arranged functionally in parallel with the first secondary link and may hence be referred to as a parallel transmission. The secondary mechanism is arranged distal of the primary mechanism. Due to the primary mechanism including a primary link movable in the primary plane, transverse to which the first and second secondary links can move, a base of the industrial robot can be positioned very close to a picking or placing region, such as a belt conveyor.

[0017] The industrial robot may further comprise an end effector carried by the secondary mechanism. The end effector may be carried directly or indirectly by the secondary mechanism. In the latter case, the end effector may be carried by a tertiary mechanism distal of the secondary mechanism. In any case, the end effector may be arranged distal of the secondary mechanism.

[0018] The primary mechanism may comprise one or more primary links and one primary actuator arranged to drive each primary link exclusively in parallel with the primary plane. In this way, the primary mechanism is resistant to gravitational forces acting on the industrial robot. In case a plurality of primary links is used, the primary links may be arranged in series.

[0019] The transmission may comprise a proximal transmission axis fixed with respect to the primary link and parallel with, and offset from, the first secondary axis and a distal transmission axis fixed with respect to the second secondary link and parallel with, and offset from, the second secondary axis. The transmission may further comprise a connection element interconnecting the proximal transmission axis and the distal transmission axis. The connection element may be rotatable relative to the primary link and to the second secondary link around the proximal transmission axis and the distal transmission axis, respectively. Since the proximal transmission axis is offset from the first secondary axis, the proximal transmission axis and the first secondary axis are in a non-concentric parallel relationship. Correspondingly, since the distal transmission axis is offset from the second secondary axis, the distal transmission axis and the second secondary axis are in a non-concentric parallel relationship. The transmission may be a linkage. The proximal transmission axis and the distal transmission axis may be positioned either at opposite sides of the first secondary link, e.g., at opposite sides of a plane comprising the first and second secondary axes, or at the same side of the first secondary link.

[0020] The connection element may be a rod. The rod may be straight, curved or bent. As a possible alternative to a rod, the connection element may be a flexible elongated member, such as a wire or a rope. In such variants, the flexible elongated member may be fixed directly to each of the primary link and the second secondary link, i.e., without any intermediate axis.

[0021] The proximal transmission axis may be positioned on a handling side of the primary plane. The handling side may be geodetically below the primary plane in cases where the primary plane is horizontal.

[0022] An offset between the proximal transmission axis and the first secondary axis may be 5 % to 60 % of a distance between the first and second secondary axes and / or of a distance between the proximal and distal transmission axes. An offset between the distal transmission axis and the second secondary axis may be 5 % to 60 % of a distance between the first and second secondary axes and / or a distance between the proximal and distal transmission axes.

[0023] A distance between the proximal transmission axis and the distal transmission axis may be at least 70 % and / or less than 130 % of a distance between the first secondary axis and the second secondary axis.

[0024] The second rotation may be less than 150 % of the first rotation. Alternatively, or in addition, the second rotation may be at least 5 % of the first rotation. When the second rotation is 90 %, 100 % and 110 %, respectively, of the first rotation, a second rotational speed of the second secondary link around the second secondary axis relative to the first secondary link, is slower, equal to and faster, respectively, with respect to a first rotational speed of the first secondary link around the first secondary axis relative to the primary link. The second secondary axis may be parallel with the first secondary axis.

[0025] The transmission may be a first transmission. In these cases, the secondary mechanism may further include a third secondary link rotatable relative to the second secondary link around a third secondary axis parallel with the primary plane; and a second transmission interconnecting the first secondary link and the third secondary link, the second transmission being configured to transmit the second rotation in the first direction to a third rotation of the third secondary link relative to the second secondary link around the third secondary axis in the first direction. By using two or more transmissions in this way, the advantages of the industrial robot according to the first aspect can be further enhanced. For example, an actuation of the secondary actuator to obtain certain movement of a most distal secondary link relative to the primary plane can be further reduced, the footprint of the industrial robot can be further reduced, and the reachability can be further improved.

[0026] The industrial robot may further comprise a tertiary mechanism including a tertiary link and a tertiary actuator arranged to drive the tertiary link to rotate relative to the secondary mechanism around a tertiary axis. In this variant, the tertiary axis may be parallel with the primary plane or transverse to the third secondary axis.

[0027] The tertiary link, the tertiary actuator and the tertiary axis may be a second tertiary link, a second tertiary actuator and a second tertiary axis, respectively. In these cases, the tertiary mechanism may further include a first tertiary link and a first tertiary actuator arranged to drive the first tertiary link to rotate relative to the secondary mechanism around a first tertiary axis transverse to the second secondary axis. Moreover, in these cases, the second tertiary axis may be transverse to the first tertiary axis. The first tertiary axis may interconnect the most distal secondary link and the first tertiary link.

[0028] The tertiary mechanism may further include a third tertiary link and a third tertiary actuator arranged to drive the third tertiary link to rotate relative to the second tertiary link around a third tertiary axis transverse to the second tertiary axis.

[0029] The industrial robot may further comprise a base. In these cases, the primary link may be movable in the primary plane relative to the base. The base may be configured to be fixed to a support surface, such as a floor, a wall or a ceiling. The primary plane may be parallel with the support surface.

[0030] The industrial robot may comprise a control system including at least one data processing device and at least one memory having at least one computer program stored therein, the at least one computer program comprising program code which, when executed by the at least one data processing device, causes the at least one data processing device to perform, or command performance of, various operations including the operations described herein.

[0031] The industrial robot may be configured to control the primary mechanism based on a rotational position of the first secondary link. Since two different rotational positions of the first secondary link correspond to two different positions of the most distal secondary link due to the kinematics of the secondary mechanism, and since the relationships therebetween is known or can be calculated, the primary mechanism can be used to provide two or three degrees of freedom of the most distal secondary link when controlled based on the rotational position of the first secondary link. The skilled person is well familiar with how to determine a position and an orientation of the most distal secondary link based on a rotational position of the first secondary link for a given secondary mechanism. Such relationships may be calculated in real time. Alternatively, such relationships may be calculated offline and stored in a lookup table that is used online.

[0032] The industrial robot may be configured to control the primary mechanism to move the primary link away from the base in the primary plane in synchronization with the first rotation. According to one variant, the primary mechanism is controlled in synchronization with the first secondary axis such that the end effector moves in a direction transverse to the primary plane.

[0033] The primary link may be a second primary link. In these cases, the primary mechanism may further include a first primary link. Moreover, in these cases, the at least one primary actuator may include a first primary actuator arranged to drive the first primary link to rotate in parallel with the primary plane and a second primary actuator arranged to drive the second primary link to rotate relative to the first primary link. The first primary link may be rotatable relative to the base. The second primary link may be rotatable relative to the first primary link.

[0034] According to a second aspect, there is provided a method of controlling an industrial robot, the method comprising providing an industrial robot according to the first aspect; and controlling, by a control system, the secondary actuator to drive the first secondary link to rotate relative to the primary link around the first secondary axis. The method according to the second aspect may include any type of operation of the industrial robot mentioned in connection with the first aspect, and vice versa.

[0035] The method may further comprise controlling the primary mechanism based on a rotational position of the first secondary link.

[0036] The method may further comprise providing an industrial robot comprising a base, where the primary link is movable in the primary plane relative to the base. In these cases, the method may further comprise controlling, by the control system, the primary mechanism to move the primary link away from the base in the primary plane in synchronization with the first rotation.

[0037] Brief Description of the Drawings

[0038] Further details, advantages and aspects of the present disclosure will become apparent from the following description taken in conjunction with the drawings, wherein: Fig. 1: schematically represents a side view of an industrial robot according to one example;

[0039] Fig. 2: schematically represents components of an industrial robot of a more generic example;

[0040] Fig. 3: schematically represents a further side view of the industrial robot in Fig. 1;

[0041] Fig. 4: schematically represents a further side view of the industrial robot in Figs. 1 and 3;

[0042] Fig. 5: schematically represents a side view of an industrial robot according to a further example;

[0043] Fig. 6: schematically represents a side view of an industrial robot according to a further example;

[0044] Fig. 7: schematically represents a further side view of the industrial robot in Fig. 6;

[0045] Fig. 8: schematically represents a further side view of the industrial robot in Figs. 6 and 7; and

[0046] Fig. 9: is a flowchart outlining general steps of a method.

[0047] Detailed Description

[0048] In the following, an industrial robot comprising a primary link, a first secondary link, a second secondary link and a transmission interconnecting the primary link and the second secondary link, and a method of controlling such industrial robot, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.

[0049] Fig. 1 schematically represents a side view of an industrial robot 10a. The industrial robot 10a of this example comprises a base 12, a primary mechanism 14 connected to the base 12, a secondary mechanism 16 distal of, and connected to, the primary mechanism 14, and a tertiary mechanism 18 distal of, and connected to, the secondary mechanism 16. Fig. 1 further shows a Cartesian coordinate system 20 for reference purposes. The base 12 is here fixed to a horizontal floor 22, which constitutes one example of a support surface.

[0050] Fig. 1 further shows a primary plane 24. Although the primary plane 24 may be oriented arbitrarily in space, the primary plane 24 of this example is horizontal and thus parallel with the floor 22. Fig. 1 further shows a handling side 26 of the primary plane 24, which in the example in Fig. 1 is positioned geodetically below the primary plane 24. In the position of the industrial robot 10a in Fig. 1, the X-direction represents a distal direction parallel with the primary plane 24.

[0051] The primary mechanism 14 of this example comprises a first primary link 28a connected to the base 12, and a first primary actuator 30a arranged to drive the first primary link 28a to rotate relative to the base 12 around a first primary axis 32a transverse to the primary plane 24. The primary mechanism 14 of this example further comprises a second primary link 28b connected to, and distal of, the first primary link 28a, and a second primary actuator 30b arranged to drive the second primary link 28b to rotate relative to the first primary link 28a around a second primary axis 32b transverse to the primary plane 24. Each of the first and second primary links 28a, 28b is arranged in parallel with the primary plane 24 and is kinematically bound to perform its respective rotational movement in parallel with the primary plane 24. The primary mechanism 14 of this example provides two degrees of freedom. Due to the first and second primary links 28a, 28b being horizontal, a total weight of the industrial robot 10a can be reduced and ground excitation forces can be kept low.

[0052] The secondary mechanism 16 of this example comprises a first secondary link 34a connected to, and distal of, the second primary link 28b, and a secondary actuator 36, such as an electric motor, arranged to drive the first secondary link 34a to rotate relative to the second primary link 28b around a first secondary axis 38a parallel with the primary plane 24. The secondary mechanism 16 of this example further comprises a second secondary link 34b connected to, and distal of, the first secondary link 34a. The second secondary link 34b is configured to rotate relative to the first secondary link 34a around a second secondary axis 38b parallel with the primary plane 24 and the first secondary axis 38a. Notably, no actuator is arranged at the second secondary axis 38b. This contributes to a cost-efficient design of the industrial robot 10a. The first secondary link 34a, the second secondary axis 38b and the second secondary link 34b form an articulated arm.

[0053] In the position of the industrial robot 10a in Fig. 1, each of the first and second secondary links 34a, 34b is arranged in parallel with the primary plane 24. Each of the first and second secondary links 34a, 34b is however kinematically bound to perform its respective rotational movement in directions transverse to the primary plane 24.

[0054] The secondary mechanism 16 of this example further comprises a transmission 40a, here embodied as a linkage. The transmission 40a of this example interconnects the second primary link 28b and the second secondary link 34b. The transmission 40a is thereby arranged in parallel with the first secondary link 34a and bypasses the first secondary link 34a. The transmission 40a of this example comprises a straight rod 42a, constituting one example of a connection element. The transmission 40a of this example further comprises a proximal transmission axis 44a interconnecting a proximal offsetting structure 46a of the second primary link 28b and the rod 42a, and a distal transmission axis 48a interconnecting the rod 42a and a distal offsetting structure 50a of the second secondary link 34b. The proximal and distal transmission axes 44a, 48a are thus fixed to the first primary link 28a and the second secondary link 34b, respectively. The rod 42a interconnects the proximal and distal transmission axes 44a, 48a. Each of the proximal and distal offsetting structures 46a, 50a is here exemplified as a rod. The proximal transmission axis 44a is here positioned on the handling side 26 of the primary plane 24. When the second secondary link 34b is parallel with the primary plane 24, like in Fig. 1, the distal transmission axis 48a is positioned on an opposite side of the primary plane 24 with respect to the handling side 26. The secondary mechanism 16 of the specific and non-limiting example in Fig. 1 has the following characteristics. The proximal transmission axis 44a is positioned on the handling side 26 of the primary plane 24 and the distal transmission axis 48a is positioned on an opposite side of the primary plane 24. The first secondary axis 38a is aligned with the proximal transmission axis 44a in a direction parallel with the primary plane 24 (e.g., the X- direction). The second secondary axis 38b is positioned distal of the distal transmission axis 48a (here in the X-direction) when the second secondary link 34b is positioned in parallel with the primary plane 24 (like in Fig. 1). A length of the rod 42a (here defined as a distance between the proximal transmission axis 44a and the distal transmission axis 48a) is here approximately 98 % of a length of the first secondary link 34a (here defined as a distance between the first and second secondary axes 38a, 38b). An offset between the proximal transmission axis 44a and the first secondary axis 38a is approximately 20 % of each of the length of the first secondary link 34a, and of the length of the rod 42a. An offset between the distal transmission axis 48a and the second secondary axis 38b is approximately 20 % of the length of the first secondary link 34a, and of the length of the rod 42a.

[0055] The tertiary mechanism 18 of this example comprises a first tertiary link 52a connected to, and distal of, the second secondary link 34b, and a first tertiary actuator 54a (Fig. 2) arranged to drive the first tertiary link 52a to rotate relative to the second secondary link 34b around a first tertiary axis 56a transverse to the second secondary axis 38b. The tertiary mechanism 18 of this example further comprises a second tertiary link 52b connected to, and distal of, the first tertiary link 52a, and a second tertiary actuator 54b arranged to drive the second tertiary link 52b to rotate relative to the first tertiary link 52a around a second tertiary axis 56b transverse to the first tertiary axis 56a. The tertiary mechanism 18 of this example further comprises a third tertiary link 52c connected to, and distal of, the second tertiary link 52b, and a third tertiary actuator 54c (Fig. 2) arranged to drive the third tertiary link 52c to rotate relative to the second tertiary link 52b around a third tertiary axis 56c transverse to the second tertiary axis 56b.

[0056] The tertiary mechanism 18 of this example further comprises an end effector 58, here exemplified as a suction gripper attached to the third tertiary link 52c. Fig. 1 further shows a mating interface 60 between the third tertiary link 52c and the end effector 58. In Fig. 1, the mating interface 60 is oriented in parallel with the primary plane 24 and the end effector 58 is thereby oriented in a direction transverse to the primary plane 24, here in a vertical direction.

[0057] The industrial robot 10a of the example in Fig. 1 comprises a first primary joint interconnecting the base 12 and the first primary link 28a and defining the first primary axis 32a, a second primary joint interconnecting the first primary link 28a and the second primary link 28b and defining the second primary axis 32b, a first secondary joint interconnecting the second primary link 28b and the first secondary link 34a and defining the first secondary axis 38a, a second secondary joint interconnecting the first secondary link 34a and the second secondary link 34b and defining the second secondary axis 38b, a first tertiary joint interconnecting the second secondary link 34b and the first tertiary link 52a and defining the first tertiary axis 56a, a second tertiary joint interconnecting the first tertiary link 52a and the second tertiary link 52b and defining the second tertiary axis 56b, a third tertiary joint interconnecting second tertiary link 52b and the third tertiary link 52c and defining the third tertiary axis 56c, a proximal transmission joint interconnecting the proximal offsetting structure 46a and the rod 42a and defining the proximal transmission axis 44a, and a distal transmission joint interconnecting the rod 42a and the distal offsetting structure 50a and defining the distal transmission axis 48a.

[0058] Fig. 1 further shows a partial cross-section of a box 62 containing a plurality of objects 64. Each object 64 may for example be a package, such as a soft and flexible poly bag, as illustrated in Fig. 1. A wall of the box 62 is denoted as 66. Fig. 1 further generally denotes examples of a picking region 68 and a placing region 70. The picking region 68 corresponds to a position of one of the objects 64. The placing region 70 may for example be a position on a belt conveyor (not illustrated). The picking and placing regions 68, 70 may be reversed.

[0059] The industrial robot 10a of this example has six degrees of freedom and can thus provide a so-called 6D (six-dimensional) pose (position and orientation) of the end effector 58. The industrial robot 10a may however be controlled to operate in a so-called wrist-down configuration where the end effector 58 points generally downwards at all times (as shown in Fig. 1). The wrist may here include the second tertiary link 52b, the third tertiary link 52c and the end effector 58. The wrist-down configuration may for example be used when access to the objects 64 is from above and when an end effector 58 based on suction is used since the suction direction can then coincide with the gravity load.

[0060] Fig. 2 schematically represents components of an industrial robot 10. The industrial robot 10a is one example of the industrial robot 10. The primary mechanism 14 comprises m primary actuators 30a-30m, m associated primary links 28a-28m and m primary sensors 72a- 72m, where m is a positive integer. Each primary sensor 72a-72m is configured to determine a rotational position of the associated primary link 28a-28m.

[0061] The secondary mechanism 16 comprises the secondary actuator 36, the associated first secondary link 34a, a secondary sensor 74, n transmissions 40a-40n and n+1 associated secondary links 34n-34n+i, where n is a positive integer. The secondary sensor 74 is configured to determine a rotational position of the first secondary link 34a.

[0062] The tertiary mechanism 18 comprises the end effector 58, p tertiary actuators 54a-54p, p associated tertiary links 52a-52p and p associated tertiary sensors 76a- 76p, where p is a positive integer. Each tertiary sensor 76a- 76p is configured to determine a rotational position of the associated tertiary link 52a-52p.

[0063] Fig. 2 further shows that the industrial robot 10 comprises a control system 78. The control system 78 of this example includes a data processing device 80 and a memory 82 having a computer program stored therein. The computer program comprises program code which, when executed by the data processing device 80, causes the data processing device 80 to perform, or command performance of, various operations including the operations described herein. The control system 78 is in signal communication with the primary actuators 30a-30m, the primary sensors 72a-72m, the secondary actuator 36, the secondary sensor 74, the tertiary actuators 54a-54p, the tertiary sensors 76a- 76p and the end effector 58.

[0064] Fig. 3 schematically represents a further side view of the industrial robot 10a. In the example in Fig. 3, the control system 78 has controlled the secondary actuator 36 to drive the first secondary link 34a to perform a first rotation 84a of approximately 22.50relative to the second primary link 28b around the first secondary axis 38a in a clockwise direction as seen in Fig. 3. The clockwise direction in Fig. 3 is one example of a first direction. From the orientation of the first secondary link 34a in Fig. 1 where the first secondary link 34a is parallel with the primary plane 24, the first rotation 84a of the first secondary link 34a causes the second secondary axis 38b to move away from the primary plane 24, here towards the floor 22.

[0065] As shown in Fig. 3, due to the kinematics of the transmission 40a, the transmission 40a transmits the first rotation 84a of the first secondary link 34a to a second rotation 84b of the second secondary link 34b relative to the first secondary link 34a around the second secondary axis 38b in the clockwise direction. The second rotation 84b of the second secondary link 34b of this example is approximately 21 °. Thus, in Fig. 3, the second secondary link 34b is angled approximately 43,50relative to the primary plane 24, which corresponds to a sum of the first and second rotations 84a, 84b. In this example, the control system 78 is configured to determine a pose of the second secondary link 34b based on the rotational position of the secondary actuator 36. Such determination can be made using an equation expressing the kinematics of the secondary mechanism 16.

[0066] Based on the pose of the second secondary link 34b, the control system 78 has controlled the second tertiary actuator 54b to drive the second tertiary link 52b to perform a tertiary rotation 86 of approximately 43,50relative to the first tertiary link 52a around the second tertiary axis 56b in a counterclockwise direction. The tertiary rotation 86 is thus a counter rotation to maintain the end effector 58 vertically oriented.

[0067] Moreover, based on the pose of the second secondary link 34b, the control system 78 has controlled the primary mechanism 14 such that the first secondary axis 38a moves away from the base 12 in the primary plane 24 in synchronization with the first rotation 84a, as shown with arrow 88. The movements of the primary mechanism 14 and of the first secondary link 34a around the first secondary axis 38a are in this example synchronized such that the second tertiary actuator 54b, and here also the end effector 58, move in a direction transverse to the primary plane 24, here in a vertically downward direction, as shown with arrow 90.

[0068] As shown in Fig. 3, the rotational motion generated by the secondary actuator 36 may be said to become distributed between the first and second rotations 84a, 84b. Thus, in order to position the second secondary link 34b at a nominal angle to the primary plane 24, the first secondary axis 38a is rotated less than this nominal angle, such as 50 % thereof. In the specific example in Fig. 3, the second secondary link 34b is positioned at an angle of approximately 43.50to the primary plane 24, but the first secondary link 34a is only positioned at an angle of approximately 22.50to the primary plane 24. Due to this distribution of the rotational motion generated by the secondary actuator 36, the requirements on the secondary actuator 36 can be relaxed. For example, for a given required rotational speed of the second secondary link 34b in space, the speed of the secondary actuator 36 can be reduced, here with approximately 50 %, in comparison with a case where the second secondary link 34b would be driven directly by the secondary actuator 36, i.e., without the intermediate first secondary link 34a. The rating of the secondary actuator 36 can thereby be reduced to improve cost-efficiency. Conversely, for a given maximum rotational speed of the secondary actuator 36, the rotational speed of the second secondary link 34b in space can be increased, here with approximately 100 %, in comparison with a case where the second secondary link 34b would be driven directly by the secondary actuator 36. Moreover, as shown in Fig. 3, the industrial robot 10a has a very lean design.

[0069] In this example, the second tertiary actuator 54b is controlled to provide a counter rotation shown as the tertiary rotation 86 such that the end effector 58 is maintained vertically oriented. The tertiary rotation 86 here amounts to a sum of the first and second rotations 84a, 84b. This counter rotation can be provided without needing the first and third tertiary axes 56a, 56c. Thus, the first and third tertiary axes 56a, 56c are optional for this functionality. In cases where the first and third tertiary axes 56a, 56c are omitted, the second tertiary axis 56b will always be oriented in parallel with the primary plane 24.

[0070] Moreover, as an alternative to the second tertiary actuator 54b, the industrial robot 10a may comprise a parallel arm mechanism to kinematically bind the end effector 58 to the vertical orientation. Such parallel arm mechanism is for example used in the IRB 460 robot sold by ABB. Also in cases where such parallel arm mechanism is used can the first and third tertiary axes 56a, 56c be omitted.

[0071] The relationship between the first and second rotations 84a, 84b, which is here approximately 50 / 50, is for example governed by a position of the proximal transmission axis 44a relative to the first secondary axis 38a, a position of the distal transmission axis 48a relative to the second secondary axis 38b, and a length of the rod 42a in relation to a length of the first secondary link 34a. For example, by positioning the proximal transmission axis 44a closer to the first secondary axis 38a, an angular distance of the second rotation 84b will decrease for a given angular distance of the first rotation 84a, and vice versa.

[0072] Fig. 4 schematically represents a further side view of the industrial robot 10a. In the example in Fig. 4, the control system 78 has controlled the secondary actuator 36 to drive the first secondary link 34a to perform the first rotation 84a of approximately 450in the clockwise direction, which is transmitted by the transmission 40a to the second rotation 84b of approximately 450in the clockwise direction. Thus, in Fig. 4, the second secondary link 34b is angled approximately 900relative to the primary plane 24.

[0073] Based on the pose of the second secondary link 34b, the control system 78 has controlled the second tertiary actuator 54b to drive the second tertiary link 52b to perform the tertiary rotation 86 of approximately 900in the counterclockwise direction. Moreover, based on the pose of the second secondary link 34b, the control system 78 has controlled the primary mechanism 14 such that the first secondary axis 38a moves further away from the base 12 in the primary plane 24 in synchronization with the first rotation 84a.

[0074] The industrial robot 10a enables performance of pick-and-place cycles fast, with both high speeds and high accelerations. As can be gathered from Fig. 4, the transmission 40a enables the end effector 58 to reach deep corners of the box 62 close to the wall 66 with a small footprint. Furthermore, due to the primary mechanism 14, the placing region 70 can be positioned close to the base 12.

[0075] When the object 64 has been picked by the end effector 58, the procedure described in connection with Figs. 1, 3 and 4 may be generally reversed to perform a placing operation at the placing region 70.

[0076] Fig. 5 schematically represents a side view of an industrial robot 10b. Mainly differences of the industrial robot 10b from the industrial robot 10a will be described. The secondary mechanism 16 of the specific and non-limiting example of the industrial robot 10b in Fig. 5 has the following characteristics. The distal transmission axis 48a is positioned on the handling side 26 of the primary plane 24. The first secondary axis 38a is positioned proximal of the proximal transmission axis 44a in a direction parallel with the primary plane 24 (e.g., the X-direction). The second secondary axis 38b is aligned with the distal transmission axis 48a in the X-direction when the second secondary link 34b is positioned in parallel with the primary plane 24 (like in Fig. 5). A length of the rod 42a is here approximately 100 % of a length of the first secondary link 34a. An offset between the proximal transmission axis 44a and the first secondary axis 38a is approximately 14 % of each of a length of the first secondary link 34a, and of a length of the rod 42a. An offset between the distal transmission axis 48a and the second secondary axis 38b is approximately 51 % of the length of the first secondary link 34a, and of the length of the rod 42a. In this example, the second rotation 84b is approximately 12.5 % of the first rotation 84a.

[0077] Fig. 6 schematically represents a side view of an industrial robot 10c. Mainly differences of the industrial robot 10c from the industrial robot 10a will be described. The primary mechanism 14 of the industrial robot 10c of this example comprises a first primary link 28a and a first primary actuator 30a arranged to drive the first primary link 28a to move linearly relative to the base 12 in parallel with the primary plane 24. The primary mechanism 14 of this example thus only provides one degree of freedom.

[0078] The secondary mechanism 16 of this example comprises the first secondary link 34a connected to, and distal of, the first primary link 28a, and the secondary actuator 36 arranged to drive the first secondary link 34a to rotate relative to the first primary link 28a around the first secondary axis 38a. The secondary mechanism 16 of this example further comprises the second secondary link 34b. The secondary mechanism 16 of this example further comprises a third secondary link 34c connected to, and distal of, the second secondary link 34b. The third secondary link 34c is configured to rotate relative to the second secondary link 34b around a third secondary axis 38c parallel with the primary plane 24 and the first secondary axis 38a. Notably, also no actuator is arranged at the third secondary axis 38c. In Fig. 6, each of the first to third secondary links 343-340 is arranged in parallel with the primary plane 24. Each of the first to third secondary links 343-340 is however kinematically bound to perform its respective rotational movement in directions parallel with a plane transverse to the primary plane 24.

[0079] In the industrial robot 10c, the transmission 40a, the rod 42a, the proximal offsetting structure 46a, the proximal transmission axis 44a, the distal transmission axis 48a and the distal offsetting structure 50a are referred to as a first transmission 40a, a first rod 42a, a first proximal offsetting structure 46a, a first proximal transmission axis 44a, a first distal transmission axis 48a and a first distal offsetting structure 50a, respectively. The secondary mechanism 16 of this example further comprises a second transmission 40b including a second rod 42b, also here embodied as a linkage. The second transmission 40a of this example interconnects the first secondary link 34a and the third secondary link 34c. The second transmission 40b is thereby arranged in parallel with the second secondary link 34b and bypasses the second secondary link 34b. The first and second transmissions 40a, 40b are here of the same design. The second transmission 40b of this example further comprises a second proximal transmission axis 44b interconnecting a second proximal offsetting structure 46b of the first secondary link 34a and the second rod 42b, and a second distal transmission axis 48b interconnecting the second rod 42b and a second distal offsetting structure 50b of the third secondary link 34c. The second proximal and distal transmission axes 44b, 48b are thus fixed to the first secondary link 34a and the third secondary link 34c, respectively. The second rod 42b interconnects the second proximal and distal transmission axes 44b, 48b. Each of the second proximal and distal offsetting structures 46b, 50b is here exemplified as a rod. When the second and third secondary links 34b, 34c are parallel with the primary plane 24, like in Fig. 6, the second proximal transmission axis 44b is positioned on the handling side 26 of the primary plane 24 and the second distal transmission axis 48b is positioned on an opposite side of the primary plane 24 with respect to the handling side 26. Fig. 7 schematically represents a further side view of the industrial robot IOC. In the example in Fig. 7, the control system 78 has controlled the secondary actuator 36 to perform the first rotation 84a of approximately 150in the clockwise direction, which is transmitted by the first transmission 40a to the second rotation 84b of approximately 140in the clockwise direction. The second transmission 40b transmits the second rotation 84b of the second secondary link 34b to a third rotation 84c of the third secondary link 34c relative to the second secondary link 34b around the third secondary axis 38c. The third rotation 84c of the third secondary link 34c of this example is approximately 130in the clockwise direction. Thus, in Fig. 7, the third secondary link 34c is angled approximately 420relative to the primary plane 24, which corresponds to a sum of the first to third rotations 843-840.

[0080] Fig. 8 schematically represents a further side view of the industrial robot 10c. In the example in Fig. 8, the control system 78 has controlled the secondary actuator 36 to drive the first secondary link 34a to perform the first rotation 84a of approximately 310in the clockwise direction, which is transmitted by the first transmission 40a to the second rotation 84b of approximately 300in the clockwise direction, which in turn is transmitted by the second transmission 40b to the third rotation 84c of approximately 290in the clockwise direction. Thus, in Fig. 8, the second secondary link 34b is angled approximately 900relative to the primary plane 24. Thus, in the industrial robot 10c, the first rotation 84a to achieve a vertical orientation of the most distal secondary link, here the third secondary link 34c, is even more reduced in comparison with the industrial robot 10a. One, several or all of the industrial robots 10, toa-ioc may also be referred to with reference numeral "10".

[0081] Fig. 9 is a flowchart outlining general steps of a method. The method comprises providing S10 an industrial robot 10 comprising a primary mechanism 14 including a primary link 28a; 28b and at least one primary actuator 30a; 30b arranged to drive the primary link 28a; 28b to move in parallel with a primary plane 24; a secondary mechanism 16 including a first secondary link 34a and a secondary actuator 36 arranged to drive the first secondary link 34a to rotate relative to the primary link 28a; 28b around a first secondary axis 38a parallel with the primary plane 24; and a second secondary link 34b rotatable relative to the first secondary link 34a around a second secondary axis 38b parallel with the primary plane 24; wherein the secondary mechanism 16 further comprises a transmission 40a interconnecting the primary link 28a; 28b and the second secondary link 34b, the transmission 40a being configured to transmit a first rotation 84a of the first secondary link 34a relative to the primary link 28a; 28b around the first secondary axis 38a in a first direction to a second rotation 84b of the second secondary link 34b relative to the first secondary link 34a around the second secondary axis 38b in the first direction.

[0082] The providing S10 may comprise providing S12 an industrial robot 10 comprising a base 12, wherein the primary link 28a; 28b is movable in the primary plane 24 relative to the base 12.

[0083] The method further comprises controlling S14, by a control system 78, the secondary actuator 36 to drive the first secondary link 34a to rotate relative to the primary link 28a; 28b around the first secondary axis 38a.

[0084] The method may further comprise controlling S16 the primary mechanism 14 based on a rotational position of the first secondary link 34a.

[0085] The controlling S16 may comprise controlling S18, by the control system 78, the primary mechanism 14 to move the primary link 28a; 28b away from the base 12 in the primary plane 24 in synchronization with the first rotation 84a.

[0086] While the present disclosure has been described with reference to exemplary embodiments, it will be appreciated that the present invention is not limited to what has been described above. For example, it will be appreciated that the dimensions of the parts may be varied as needed. Accordingly, it is intended that the present invention may be limited only by the scope of the claims appended hereto.

Claims

23CLAIMS1. An industrial robot (io) comprising:- a primary mechanism (14) including a primary link (28a; 28b) and at least one primary actuator (30a; 30b) arranged to drive the primary link (28a; 28b) to move in parallel with a primary plane (24);- a secondary mechanism (16) including a first secondary link (34a) and a secondary actuator (36) arranged to drive the first secondary link (34a) to rotate relative to the primary link (28a; 28b) around a first secondary axis (38a) parallel with the primary plane (24); and- a second secondary link (34b) rotatable relative to the first secondary link (34a) around a second secondary axis (38b) parallel with the primary plane (24); characterized in that the secondary mechanism (16) further comprises a transmission (40a) interconnecting the primary link (28a; 28b) and the second secondary link (34b), the transmission (40a) being configured to transmit a first rotation (84a) of the first secondary link (34a) relative to the primary link (28a; 28b) around the first secondary axis (38a) in a first direction to a second rotation (84b) of the second secondary link (34b) relative to the first secondary link (34a) around the second secondary axis (38b) in the first direction.

2. The industrial robot (10) according to claim 1, wherein the transmission (40a) comprises a proximal transmission axis (44a) fixed with respect to the primary link (28a; 28b) and parallel with, and offset from, the first secondary axis (38a), a distal transmission axis (48a) fixed with respect to the second secondary link (34b) and parallel with, and offset from, the second secondary axis (38b), and a connection element (42a) interconnecting the proximal transmission axis (44a) and the distal transmission axis (48a), the connection element (42a) being rotatable relative to the primary link (28a; 28b) and to the second secondary link (34b) around the proximal transmission axis (44a) and the distal transmission axis (48a), respectively.

3. The industrial robot (io) according to claim 2, wherein a distance between the proximal transmission axis (44a) and the distal transmission axis (48a) is at least 70 % and / or less than 130 % of a distance between the first secondary axis (38a) and the second secondary axis (38b).

4. The industrial robot (10) according to any of the preceding claims, wherein the second rotation (84b) is less than 150 % of the first rotation (84a).

5. The industrial robot (10) according to any of the preceding claims, wherein the second secondary axis (38b) is parallel with the first secondary axis (38a).

6. The industrial robot (10) according to any of the preceding claims, wherein the transmission (40a) is a first transmission, and wherein the secondary mechanism (16) further includes:- a third secondary link (34c) rotatable relative to the second secondary link (34b) around a third secondary axis (38c) parallel with the primary plane (24); and- a second transmission (40b) interconnecting the first secondary link (34a) and the third secondary link (34c), the second transmission (40b) being configured to transmit the second rotation (84b) in the first direction to a third rotation (84c) of the third secondary link (34c) relative to the second secondary link (34b) around the third secondary axis (38c) in the first direction.

7. The industrial robot (10) according to claim 6, wherein the third secondary axis (38c) is parallel with the first secondary axis (38a).

8. The industrial robot (10) according to any of the preceding claims, further comprising a tertiary mechanism (18) including a tertiary link (52b) and a tertiary actuator (54b) arranged to drive the tertiary link (52b) to rotate relative to the secondary mechanism (16) around a tertiary axis (56b).

9. The industrial robot (io) according to claim 8, wherein the tertiary link (52b), the tertiary actuator (54b) and the tertiary axis (56b) are a second tertiary link (52b), a second tertiary actuator (54b) and a second tertiary axis (56b), respectively, wherein the tertiary mechanism (18) further includes a first tertiary link (52a) and a first tertiary actuator (54a) arranged to drive the first tertiary link (52a) to rotate relative to the secondary mechanism (16) around a first tertiary axis (56a) transverse to the second secondary axis (38b), and wherein the second tertiary axis (56b) is transverse to the first tertiary axis (56a).

10. The industrial robot (10) according to claim 9, wherein the tertiary mechanism (18) further includes a third tertiary link (52c) and a third tertiary actuator (54c) arranged to drive the third tertiary link (52c) to rotate relative to the second tertiary link (52b) around a third tertiary axis (56c) transverse to the second tertiary axis (56b).

11. The industrial robot (10) according to any of the preceding claims, wherein the primary link (28a; 28b) is a second primary link (28b), wherein the primary mechanism (14) further includes a first primary link (28a), and wherein the at least one primary actuator (30a; 30b) includes a first primary actuator (30a) arranged to drive the first primary link (28a) to rotate in parallel with the primary plane (24) and a second primary actuator (30b) arranged to drive the second primary link (28b) to rotate relative to the first primary link (28a).

12. A method of controlling an industrial robot (10), the method comprising:- providing (S10) an industrial robot (10) according to any of the preceding claims; and- controlling (S14), by a control system (78), the secondary actuator (36) to drive the first secondary link (34a) to rotate relative to the primary link (28a; 28b) around the first secondary axis (38a).2613- The method according to claim 12, further comprising:- controlling (S16) the primary mechanism (14) based on a rotational position of the first secondary axis (38a).

14. The method according to claim 12 or 13, wherein the method comprises: - providing (S12) an industrial robot (10) according to claim 9; and- controlling (S18), by the control system (78), the primary mechanism (14) to move the primary link (28a; 28b) away from the base (12) in the primary plane (24) in synchronization with the first rotation (84a).

Images