A hybrid manipulator capable of independently controlling the position and orientation of the end effector

Abstract

The invention relates to a hybrid manipulator that can independently control the position and orientation of an end effector. In particular, the invention relates to a hybrid manipulator consisting of a combination of a series and a parallel manipulator that can independently control the position and orientation of the end effector in industrial applications such as precision surface machining, precision assembly and operational medical devices.

Description

[0001] A HYBRID MANIPULATOR CAPABLE OF INDEPENDENTLY CONTROLLING THE POSITION AND ORIENTATION OF THE END EFFECTOR

[0002] Technical Field

[0003] The invention relates to a hybrid manipulator that can independently control the position and orientation of an end effector.

[0004] In particular, the invention relates to a hybrid manipulator consisting of a combination of a series and a parallel manipulator that can independently control the position and orientation of the end effector in industrial applications such as precision surface machining, precision assembly and operational medical devices.

[0005] State of the Art

[0006] Manipulators are mechanical devices designed to change the position and orientation of objects. These devices generally comprises solid limbs connected to each other by elements that allow relative movement, called joints. These mechanical systems have a certain working volume (space); that is, they can reach points within a certain volume. Robot manipulators are programmable and / or autonomous manipulators that can make decisions on their own thanks to special equipment. These manipulators, often used in industrial applications, are designed to carry out moving, placing, assembling, and other similar tasks through one or more limbs of the robot. The following examples can be given for the fields of application of manipulators:

[0007] • Industrial robots: They are robot manipulators used in industrial applications such as production lines, assembly operations and material handling. These robots usually have multi-axis joints and can make precise movements.

[0008] • Laboratory manipulators: They are manipulators used in scientific research and experiments. For example, they can be used to hold, examine, or manipulate samples under a microscope.

[0009] • Medical manipulators: They are manipulators generally used for diagnosis and surgical operations.

[0010] • Remote manipulation systems: They are manipulators designed to work by staying away from dangerous environments such as radioactive areas. In these systems, there is an operator who controls the manipulator remotely. Assembly line manipulators: They are manipulators used to assemble parts or perform assembly operations on production lines.

[0011] In general, manipulators, and thus robot manipulators, comprises solid or solid-like objects connected by joints. Joints allow objects to move relative to each other. Joints usually comprise motors, sensors, and control units. Robot manipulators help people avoid difficult, repetitive and / or dangerous tasks and increase productivity.

[0012] It is known that serial manipulators and parallel manipulators are used in the state of the art. A serial manipulator is a mechanical system in which objects called links are successively connected by means of joints. These joints allow each link to rotate or translate relative to the previous one. In this way, the link of the manipulator farthest from the end effector can move an object from one place to another with the desired velocity and acceleration in the desired position and orientation. The serial robot manipulators used in industry is generally have 6 degrees of freedom. Thus, it allows the end effector or the object held by the end effector to be brought to the desired position (3 degrees of freedom are for this) and the desired orientation (the remaining 3 degrees of freedom are forthis). In these manipulators, although forward kinematics is mathematically easier, inverse kinematics is more difficult. Although there are varieties of serial manipulators with different kinematics structures, the most widely used type in the industry is anthropomorphic (human arm resembling) manipulators. Serial manipulators may rarely have extra (redundant) degrees of freedom.

[0013] In parallel manipulators, the body and the end effector are comprised of links or groups of links that extend directly between the body and the end effector instead of sequentially connected links from the body. These manipulators provide higher velocity, acceleration, payload capacity, accuracy, precision and homogeneous load distribution than serial manipulators. The degrees of freedom preferred in parallel manipulators is generally 6, and three of these degrees of freedom are used to determine the position of the end effector and the remaining three are used to determine its orientation. In this manipulator, 6 legs (hydraulic cylinders or electric motor driven ball screw or rack and pinion gears) connect the upper and lower platforms.

[0014] In the state of the art, it is known to use hybrid manipulators that combine the large operating space properties of serial manipulators with the positional precision of parallel manipulators and other positive properties mentioned above. Since these manipulators generally have a high (redundant) degree of freedom, it is seen that their energy consumption is high and controlling them is difficult.

[0015] Moser B.L. et al. (2021) presented in their study that the hybrid manipulator has a total of 12 degrees of freedom, 6 in the serial manipulator and 6 in the parallel manipulator. It is known that 6 degrees of freedom are sufficient to bring an object to the desired position and orientation in 3D space. The having the extra degrees of freedom here makes it difficult to control, and the cost is higher because the number of motors required is bigger.

[0016] Kuguk S., Gungor B.D. (2016) in the hybrid manipulator presented in his study, the parallel manipulator section has 6 degrees of freedom and an additional degree of freedom. In the relevant design, some of the position control is provided through the serial manipulator (2 degrees of freedom) and some is provided through the parallel manipulator. Thus, position control is not entirely independent from orientation control. Therefore, the control of this design is complex and has excessive degrees of freedom and motors.

[0017] As a result, due to the said disadvantages and the insufficiency of the current solutions regarding the subject matter, a development is required to be made in the relevant technical field.

[0018] Objective of the Invention

[0019] The invention relates to a hybrid manipulator comprising a serial manipulator followed by a parallel manipulator, where the excess degrees of freedom are eliminated, and the position and orientation of the end effector can be independently controlled, especially in inverse kinematics. The two said issues eliminate the dependence between the excess degrees of freedom control in existing hybrid structures and the position and orientation of the end effector. This is the first object of the invention.

[0020] Another object of the invention is to provide an easily controllable hybrid manipulator suitable for use in precise operations.

[0021] Another object of the invention is to provide ease of control and energy conservation by reducing the number of excess motors. The invention is a hybrid manipulator that allows independent control of the position and orientation of an end effector or a set fixed to this end effector in order to achieve said objects, which comprises the following:

[0022] • a parallel manipulator with three degrees of freedom comprising the following components to enable manipulation of the object to be operated upon: o a first platform, fixed to the last link of the serial manipulator that forms the first part of the hybrid manipulator, but in detachable form. o a second platform positioned with a gap between the first platform to provide manipulation to the object to be operated upon, o three universal joints located near the edges of the first platform, o three spherical joints located near the edges of the second platform, o three cylinders, each connected to the universal joints, providing rotational capability in two axes, o three pistons, which have been provided with rotational capability in three axes by moving linearly within said cylinders to enable the second platform to do rotational motion and being connected with the spherical joint, o a fixed rod, one end of which is fixed to the center point of the first platform, the other end of which is connected to the center point of the second platform by a spherical joint, to prevent the second platform from making relative translational movement, and

[0023] • a serial manipulator connected by a parallel manipulator and having three degrees of freedom to bring the parallel manipulator to the desired coordinates within the operating space, comprising: o a sliding link to control the position of the hybrid manipulator in the Z axis by making translational movement in the Z axis, o the first rotational link to control the position of the hybrid manipulator in the X and Y axis by doing rotational motion in a plane parallel to the X-Y plane, which is connected to the sliding link on a point close to the apex point, o the second rotational link, integrated with the first rotational link at its end point and doing rotational motion in a plane parallel to the X-Y plane, to control the hybrid manipulator's position along the X and Y axes in a unified structure with the first platform.

[0024] The structural and characteristic features and all the advantages of the invention will be understood more clearly by means of the figures and the detailed description with reference to these figures provided below and therefore, the evaluation should be made by taking these figures and the detailed description into consideration.

[0025] Figures for a Better Understanding of the Invention

[0026] Figure 1 is the overview of the hybrid manipulator.

[0027] Figure 2 is the overview of the parallel manipulator.

[0028] Figure 3 is the exploded view of the hybrid manipulator.

[0029] Descriptions of Component References

[0030] 10 Hybrid manipulator

[0031] 20 Serial manipulator

[0032] 21 Sliding link

[0033] 22 First rotational link

[0034] 23 Second rotational link

[0035] 30 Parallel manipulator

[0036] 31 First platform

[0037] 32 Second platform (end effector)

[0038] 33 Cylinder

[0039] 34 Piston

[0040] 35 Universal joint

[0041] 36 Spherical joint

[0042] 37 Fixed rod

[0043] 40 Base Detailed Description of the Invention

[0044] In this detailed description, the preferred embodiments of the hybrid manipulator (10) of the invention are described only for a better understanding of the subject.

[0045] The hybrid manipulator (10) of the invention fundamentally comprises of a serial manipulator (20) and a parallel manipulator (30) connected to each other and fixed to the ground with a base (40).

[0046] Said serial manipulator (20) basically comprises a sliding link (21 ), a first rotational link (22) and a second rotational link (23). The sliding link (21 ) is positioned on the base (40) and does translational movement along the Z axis to control the hybrid manipulator's (10) position in the Z axis. The first rotational link (22) is connected to the sliding link (21 ) near its apex point, allowing rotational motion in the X-Y plane to control the position of the hybrid manipulator (10) along the X and Y axes. The second rotational link (23) is connected to the end point of the first rotational link (22), enabling rotational motion in the X-Y plane to control the position of the hybrid manipulator (10) along the X and Y axes.

[0047] Said parallel manipulator (30) basically comprises a first platform (31 ), a second platform (end effector) (32), cylinders (33), pistons (34) (or electric motor components), universal joint (35), spherical joint (36) and a fixed rod (37). The first platform (31) is in a tabular shape and is rigidly connected to the end of the second rotational link (23) of the serial manipulator. The first platform (31) can be selected in triangular, circular, or other geometric shapes.

[0048] The second platform (32) is positioned at a specific distance from the first platform (31 ) and acts as the end effector of the hybrid manipulator (10) of the invention and provides manipulation of the object to be operated upon. The second platform (32) is positioned parallel or near parallel to the first platform (31), with a gap between them. The second platform (32) and the first platform (31) are connected in a way that will put a distance between them. In the nominal position, the two platforms are parallel to each other.

[0049] The first platform (31 ) has three universal joints (35) in points near to its edges, and the second platform (32) has three spherical joints (36) in points near to its near its edges. Said universal joints (35) and said spherical joints (36) are connected to their respective platforms (first platform (31 ) and second platform (32)) with preferably 120 degree angles between them. Each of the universal joints (35) is connected to a cylinder (33); each of the spherical joints (36) is connected to a piston (34). (If an electric motor is used, it is connected to the body of the electric motor and the linearly moving shaft.) Accordingly, the parallel manipulator (32) comprises three cylinders (33) and three pistons (34). Said pistons (34) can move linearly within said cylinders (33), and by said cylinder (33), hydraulic cylinder is meant. Hydraulic cylinders require precision servo valves. However, instead of hydraulic drive units, rack and pinion, ball screw, or rotor disc electric motors can also be used. Electric drive is relatively clean. Pistons (34) and cylinders (33) working together provides the orientation of the second platform (32) according to the first platform (31). Universal joints (35) ensure that the cylinders (33) to which they are connected have the ability to move in a way that allows them to rotate on two different axes. The spherical joints (36) ensure that the pistons (34) and the second platform (32) to which they are connected have the ability to move in a way that allows them to rotate on three axes. If electric motors are used, rod shaped links connected to the rotor disc with the universal joint and spherical joint to the end effector can be used instead of hydraulic cylinders. If a ball screw or rack and pinion electric motor is used, the motor body is connected to the first platform with the universal joint.

[0050] In the parallel manipulator (30), there is a fixed rod (37) attached to the center point of the first platform (31 ), with its other end connected to the center point of the second platform (32) with a spherical joint (36). The fixed rod (37) prevents the second platform (32) from making a relative translational movement with respect to the first platform (31) and allows the cylinder (33) and the pistons (34) to determine only the orientation of the second platform (32).

[0051] In another preferred embodiment of the invention, a linear motor can be used instead of the cylinder (33).

[0052] In the hybrid manipulator (10) of the invention, the position of the end effector which is the second platform (32), is determined solely by the operation of the serial manipulator (20), while its orientation is determined solely by the operation of the parallel manipulator (30). Thus, the translational and rotational movements can be controlled independently of each other and a structure that does not have excessive degrees of freedom (full degree of freedom [six degrees of freedom]) is put forward. The serial manipulator (20) has three degrees of freedom and brings the parallel manipulator (30) to the desired coordinates within the operating space. The parallel manipulator (30) also has three degrees of freedom and allows the manipulation to be made on the object to be operated upon.

[0053] 5

[0054] REFERENCES

[0055] Moser, B. L., Gordon, J. A., & Petruska, A. J. (2021). Unified Parameterization and Calibration of Serial, Parallel, and Hybrid Manipulators. Robotics, 10(4), 124.

[0056] Kupiik, S., Gungor, B. D. (2016). Inverse Kinematic Solution of a New Hybrid Robot Proposed for Medical Purposes. Medical Technologies Congress TIPTEKNO, Antalya, IEEE, 42-45.

[0057] Seguchi, Y., Tanaka, M., Kazuyuki, H. (1991). Criteria-oriented configuration control of adaptive structure and its modular neural network representation. Joint U. S. / Japan Conference on Adaptive Structures, Maui, HI, 402-421.

[0058] Hu, B., Shi, Y., Xu, L., Bai, P. (2020). Reconsideration of terminal constraint / mobility and kinematics of 5-DOF hybrid manipulators formed by one 2R1T PM and one RR SM. Mechanism and Machine Theory, 149:, 103837. https: / / doi.Org / 10.1016 / J.MECHMACHTHEGRY.2020.103837

[0059] Kopmaz, O., Ozcan, R., & Paia, Y. (1992). The Determination of Trajectory in a 5R-1 P Manipulator Using Regular Space Curves. In Proceedings of the ASME First European Joint Conference on System Design and Analysis (Vol. 1 , pp. 173-179).

[0060] Duzgun, E., & Kopmaz, O. (2022). Two Practical Methods for the Forward Kinematics of 3-3 Type Spatial and 3-RRR Planar Parallel Manipulators. Applied Sciences, 12(24), 12811.

[0061] Yildiz, A., & Kopmaz, O. (2017). Mathematical Modelling And Simulation Of A Torsional Bar Actuated Trunk Lid Mechanism For A Passenger Car. International Journal of Advances in Engineering & Technology, 10(1), 1.

[0062] Telli, S. (2000). Analysis of the dynamic behavior of a flexible limb manipulator (PhD Thesis, Bursa Uludag University).

[0063] Duzgun, E. (2023). Development of New Methods for Advanced Kinematic Solution of Parallel and Hybrid Manipulators (Doctoral Thesis, Bursa Uludag University).

[0064] Waiboer, R., Aarts, R., & Jonker, B. (2005, January). Modelling and identification of a six axes industrial robot. In International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (Vol. 47438, pp. 2265-2274). Vinh, N. X., Lam, N. N., & Thanh, N. M. (2015). Experimental system for the optimization of the parallel manipulator control. Journal of Computer Science and Cybernetics, 31 (2), 83-96.

[0065] Dasgupta, B., & Mruthyunjaya, T. (2000). The Stewart platform manipulator: a review. Mechanism and machine theory, 35(1), 15-40.

Claims

CLAIMS1. A hybrid manipulator (10) which allows the independent control of the position and orientation of an end effector or a set fixed to this end effector, characterized by comprising:• a parallel manipulator (30) has three degrees of freedom and comprising the following components to enable manipulation of the object to be operated upon and: o a first platform (31), fixed to the last link of the serial manipulator (20) that forms the first part of the hybrid manipulator (10), but in detachable form, o a second platform (32) positioned with a gap between the first platform(31 ) to provide manipulation to the object to be operated upon, o three universal joints (35) located nearthe edges of the first platform (31), o three spherical joint (36) located near the edges of the second platform(32), o three cylinders (33), each connected to the universal joints (35), providing rotational capability in two axes, o three pistons (34), which have been provided with rotational capability in three axes by moving linearly within said cylinders (33) to enable the second platform (32) to do rotational motion and being connected with the spherical joint (36), o a fixed rod (37), one end of which is fixed to the center point of the first platform (31 ), the other end of which is connected to the center point of the second platform (32) by a spherical joint (36), to prevent the second platform (32) from making relative translational movement, and• a serial manipulator (20) connected by a parallel manipulator (30) and having three degrees of freedom to bring the parallel manipulator (30) to the desired coordinates within the operating space, comprising:o a sliding link (21) to control the position of the hybrid manipulator (10) in the Z axis by making translational movement in the Z axis, o a first rotational link (22) which is connected to the sliding link (21 ) near its apex point, allowing rotational motion parallel to the X-Y plane to control the position of the hybrid manipulator (10) along the X and Y axes. o a second rotational link (23) which is connected to the end point of the first rotational link (22) which enables rotational motion parallel to the X- Y plane to control the position of the hybrid manipulator (10) along the X and Y axes which is connected to the first platform (31 ).

2. The hybrid manipulator (10) according to claim 1 , characterized by comprising a base (40) to secure the serial manipulator (20) to the ground.

3. The hybrid manipulator (10) according to claim 1 or 2, characterized in that the first platform (31 ) can be selected in triangular, circular, or other geometric shapes.

4. The hybrid manipulator (10) according to any of the preceding claims, characterized in that the second platform (32) is positioned parallel or near parallel to the first platform (31 ), with a gap between them in nominal condition.

5. The hybrid manipulator (10) according to any of the preceding claims, characterized in that the universal joints (35) are connected to the first platform (31 ) with a 120 gap between them.

6. The hybrid manipulator (10) according to any of the preceding claims, characterized in that the spherical joints (36) are connected to the second platform (32) with a 120 gap between them.

7. The hybrid manipulator (10) according to any of the preceding claims, characterized in that said cylinder (33) is hydraulic cylinder.

8. The hybrid manipulator (10) according to any of the preceding claims, characterized in that the drive is provided from a linear motors or rotary motors instead of the cylinder (33).

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