Adaptive gripper finger mechanism, gripper device and method of using adaptive gripper device mechanism

Abstract

A gripper finger (1) for a gripper device having a monolithic elastic structure comprising an inside arm (2) having a first folding point (8) forming an angle C; an outside arm (3) having a second folding point (9), wherein the inside arm (2) or the outside arm (3) comprises a gripping surface (7) for contacting an object to be gripped; a first base end (10), from which the inside arm (2) is extending, and a second base end (11), from which the outside arm (3) is extending; a tip portion (6) where the end of the outside arm (3) and the end of the inside arm (2) are connected to each other, and at least one support arm between the inside arm (2) and the outside arm (3), wherein a first support arm (5) is provided between the first folding point (8) and the outside arm (3).

Description

[0001] ADAPTIVE GRIPPER FINGER MECHANISM, GRIPPER DEVICE AND METHOD OF USING ADAPTIVE GRIPPER DEVICE MECHANISM

[0002] TECHNICAL FIELD

[0003] The present invention relates to gripper mechanism devices and a method using gripper devices.

[0004] BACKGROUND OF THE ART

[0005] In most of today's industries where the automatization is present, required or planed, automated mechanical systems, manipulators, as well as classical industrial robots (e.g. robotic arms, scara robots, parallel robots, delta robots) need end-tool in order to grasp or manipulate with different objects and perform various tasks (e.g. pick and place, assembly and other diversity of tasks) . End-tool in these systems is also known as end-effector, gripper, grasper, material handling tool, robotic hand. Beside robots there are many other examples in industry in different mechanical systems, automated systems, cartesian systems where the gripper is used as end-tool for gripping and manipulation with ob- j ects .

[0006] Current solutions of grippers have grown complex and expensive, as everyday manufacturing tasks require more complicated operation. Thus, there is a great need for more versatile / adaptive and affordable end-tools. Most of the existing solutions of grippers have limitations and disadvantages. For example:

[0007] - they can manipulate with only limited number of objects i.e. they can grasp only limited shape and size of objects, as well as objects with limited variations in stiffness i.e. objects that are mostly considered rigid (larger stiffness) , - for every different application and industry, different grippers exist i.e. one gripper solution for only one specific type, shape, size, and stiffness of object. Grippers are usually developed and designed to handle only one type of object or product thus in most cases for every application, type of object (within some range of dimensions and weight) and industry, one gripper solution exists that can handle only this object and in case that other type of object is needed to be handled, different solution of a gripper is needed,

[0008] - most of the existing grippers cannot grasp soft and easily squeezable objects, like fruits, eggs, vegetables, plants, and bakery products (bread, pastry etc.) ,

[0009] - they represent complex solutions with lots of moving parts, rigid links, joints, electrical motors, steel cables, they require complex assembling,

[0010] - they have bad scalability, i.e. they cannot be so easily scale down to micro-domain sizes,

[0011] - some solutions of grippers require complicated grasping force control algorithms in order to grasp different ob j ects ,

[0012] - existing solutions of adaptive grippers and universal grippers that can manipulate with broader range of objects are too much expensive, complicate to produce, some require assembly, and have other disadvantages, the grippers that can grasp objects of different shapes, sizes, stiffness usually require force control and are very expensive,

[0013] - in general, most of the gripping tasks are realized with grippers and methods that require exact force and stroke control of the needed input actuation,

[0014] - in general, most of the gripping solutions are expensive and complicated to produce.

[0015] In general, most of the existing gripping solutions cannot adapt to different types of objects (different shape, size, weight, and stiffness of object) , thus in most cases different grippers are needed to handle different types of objects.

[0016] For example, paper "Adaptive Soft Robotic Gripper Based on a Shape-Morphing Compliant System" by the inventor describes compliant system for developing adaptive grippers. Disclosed compliant systems have a structure with integrated / embedded active elements, e.g. actuators, and sensors working together with the structure. These components are essential to the overall functionality of the compliant systems, i.e. the adaptive shape-morphing is made possible through the actuation of its embedded active elements.

[0017] OBJECTIVE OF THE INVENTION

[0018] The objective of the invention is to alleviate the disadvantages mentioned above which is achieved by a new simple monolithic adaptive gripper solution.

[0019] SUMMARY

[0020] To overcome the above-mentioned disadvantages, a new gripper finger and gripper device is provided for grasping and manipulating objects. The gripper finger is in form of simple monolithic elastically deformable compliant structure that can transfer motion / forces from a power source to the object to be gripped. The monolithic structure does not require assembling and, thus, the device is easy and low-cost to produce. With the specially and optimally designed structure, the same gripper finger can grasp different types of objects (different size, shape, stiffness etc.) . Also because of the new structure, it is not required to have force / input motion control to grasp objects. The elastic gripper fingers do not squeeze or break the object but rather adapt to the object shape. Or if the object is stiff, it would rather deform the gripper fingers and not the obj ect . By holding the gripper fingers in deformed state , the gripper device is closed and holds the obj ect . When the input force is no longer applied, the gripper device would open and return to its initial , undeformed state due to releas ing o f the stored strain energy, similar to a spring .

[0021] Further, the force applied to the gripper finger is trans ferred to the obj ect more ef ficiently and, thus , the needed power / force is smaller . Moreover, the input motion applied to the gripper finger is trans ferred more ef ficiently to the output and, thus , the need actuation input stroke to grip the obj ect , is smaller .

[0022] Further, the structure of the gripper finger may be simpler as there is no need of integrated or embedded active elements , such as actuators , within the structure .

[0023] According to a first aspect , the present invention provides a gripper finger for a gripper device having a monolithic elastic structure comprising

[0024] - an inside arm having a first folding point forming an angle ,

[0025] - an outside arm, wherein the inside arm or the outs ide arm comprises a gripping surface for contacting an obj ect to be gripped,

[0026] - a first base end, from which the inside arm is extending, and a second base end, from which the outs ide arm is extending,

[0027] - a tip portion where the end of the outside arm and the end of the inside arm are connected to each other, and

[0028] - at least one support arm between the inside arm and the outside arm, wherein

[0029] - a first support arm is provided between the first folding point and the outside arm . The advantage of the new design is that less energy is needed on deforming the gripper mechanism than previous grippers . Thus , heavier obj ects may be grasped and li fted, although the footprint of the gripper mechanism is similar to the previous gripper mechanisms .

[0030] In an embodiment of the device the first support arm is provided between the first folding point and the second base end .

[0031] In an embodiment of the device , the outer arm comprises a second folding point and the first support arm is provided between the first folding point and the second folding point .

[0032] In an embodiment of the device , the first support arm is provided between the first folding point and the second base end and a second support arm is provided between the first folding point and the second folding point .

[0033] In an embodiment of the device , the first base end comprises a protrusion extending to a direction that di ffers from the inside arm direction .

[0034] According to a second aspect , the present invention provides an adaptive gripper device comprising at least two gripper fingers according to any of the preceding embodiments

[0035] - the gripper fingers are monolithic elastic structures arranged to grip an obj ect via elastic deformation, and

[0036] - the gripping surfaces of the gripping fingers are facing each other so that an open space for the obj ect to be gripped is arranged between the gripping surfaces , or the gripping surfaces are facing outwards whereby gripping surfaces may be pushed towards the inner surfaces of the obj ect , wherein a first support arm is provided between the first folding point and the outside arm .

[0037] In an embodiment of the device , the gripper device comprises a frame structure in which the second base ends are fixed .

[0038] In an embodiment of the device , the device compri ses a connection point where the first base ends of the gripper fingers are connected to each other so that an angle A is provided between the inner arms of the gripper fingers .

[0039] In an embodiment of the device , the device comprises actuation means arranged in connection with the connection point and being on opposite side to the angle A for connecting the gripper device to an actuator .

[0040] In an embodiment of the device , the whole gripper device is a monolithic structure .

[0041] In an embodiment of the device , the gripper device comprises an actuator connected to actuation means for pivoting the tip portions of the gripper fingers for gripping the obj ect .

[0042] In an embodiment of the device , the actuator is arranged to pivot the tip portions of the gripper fingers farther from each other .

[0043] In an embodiment of the device the actuator is a solenoid actuator .

[0044] Another aspect is to provide a method for gripping an obj ect with an adaptive gripper device according to any of preceding embodiments of the gripper device comprising steps of

[0045] - actuating an input force to the adaptive gripper device independent from the obj ect , - converting the input force via elastic deformation of the gripper mechanism to corresponding gripping force , and

[0046] - gripping the obj ect via stored deformation energy of the gripper device in combination with the input force .

[0047] It is to be understood that the aspects and embodiments of the invention described above may be used in any combination with each other . Several of the aspects and embodiments may be combined together to form a further embodiment of the invention .

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings , which are included to provide a further understanding of the invention and constitute a part of this speci fication, illustrate embodiments of the invention and together with the description help to explain the principles of the invention . In the drawings :

[0050] Fig . 1 , 3 and 5 show gripper fingers according to first aspect ,

[0051] Fig . 2 , 4 and 6 show gripper devices comprising two gripper fingers .

[0052] DETAILED DESCRIPTION

[0053] Figures show di fferent kind of embodiments of the gripper finger and gripper device .

[0054] Figure 1 shows a monolithic and elastic gripper finger for a gripper device having a monolithic elastic structure comprising an inside arm 2 having a f irst folding point 8 , forming an angle C, and an outside arm 3 . The inside arm 2 or the outside arm 3 compri ses a gripping surface for contacting an obj ect to be gripped . In figure 1 , the gripping surface 7 is at the inner arm and, thus , the obj ect is configured to be gripped with the inner arm . The gripper finger comprises a first base end 10 , from which the inside arm 2 is extending, and a second base end 11 , from which the outside arm 3 is extending . A tip portion 6 is provided at the end of the gripper f inger , where the end of the outside arm 3 and the end of the inside arm 2 are connected to each other . The gripper finger 1 comprises a support arm 5a between the inside arm and the outside arm so that the first support arm 5a is provided between the first folding point 8 and the second base end 11 of the outside arm 3 . The gripper finger may comprise , as shown in figures , a first protrusion 12 extending from the first base end 10 in direction that dif fers from the inside arm direction .

[0055] Figure 2 shows a gripper device 15 comprising two gripper fingers 1 shown in figure 1 . With two or more gripper fingers , the gripper device is capable to grip an obj ect via elastic deformation . Each gripper finger comprises gripping surfaces 7 so that an open space for the obj ect to be gripped is arranged between the gripping surfaces ( as shown in figure 2 ) . Optionally, the gripping surfaces are facing outwards for gripping hollow or tubelike obj ects , whereby the gripping surfaces may be pushed towards the inner surfaces of the obj ect . Each of the gripping fingers comprises a first support arm 5a provided between the first folding point 8 and the outside arm 3 . In figure 2 , the first support arm 5a is provided between the first folding point 8 and the second base end 11 of the outside arm 3 . The gripper finger comprises a frame structure 14 in which the second base end 11 is fixed . Further, the gripper device 15 comprises a connection point 20 where the first base ends 10 are connected to each other so that an angle A is provided between the inner arms 2 of the gripper fingers 1 . Further, the gripper device 15 comprises actuation means 21 arranged in connection with the connection point 20 and being on opposite side to the angle A for connecting the gripper device to an actuator . As shown in figure 2 , the whole gripper device may be a monolithic structure .

[0056] Figure 3 shows a monolithic and elastic gripper finger for a gripper device having a monolithic elastic structure comprising an inside arm 2 having a f irst folding point 8 , forming an angle C, and an outside arm 3 comprising a second folding point 9 . The inside arm 2 or the outside arm 3 comprises a gripping surface for contacting an obj ect to be gripped . In figure 3 , the gripping surface 7 is at the inner arm and, thus , the obj ect is configured to be gripped with the inner arm . The gripper finger comprises a first base end 10 , from which the inside arm 2 is extending, and a second base end 11 , from which the outside arm 3 is extending . A tip portion 6 is provided at the end of the gripper finger, where the end o f the outs ide arm 3 and the end of the inside arm 2 are connected to each other . The gripper finger 1 comprises a support arm 5a between the inside arm and the outside arm so that the first support arm 5a is provided between the first folding point 8 and the second folding point 9 . The gripper finger may comprise , as shown in figures , a first protrusion 12 extending from the first base end 10 in direction that di f fers from the inside arm direction .

[0057] Figure 4 shows a gripper device 15 comprising two gripper fingers 1 shown in figure 3 . With two or more gripper fingers , the gripper device is capable to grip an obj ect via elastic deformation . Each gripper finger comprises gripping surfaces 7 so that an open space for the obj ect to be gripped is arranged between the gripping surfaces ( as shown in figure 4 ) . Optionally, the gripping surfaces are facing outwards for gripping hollow or tubelike obj ects , whereby the gripping surfaces may be pushed towards the inner surfaces of the obj ect . Each of the gripping fingers comprises a first support arm 5a provided between the first folding point 8 and the outside arm 3 . In figure 4 , the first support arm 5a is provided between the first folding point 8 and the second folding point 9 . The gripper finger comprises a frame structure 14 in which the second base end 11 is fixed . Further, the gripper device 15 comprises a connection point 20 where the f irst base ends 10 are connected to each other so that an angle A is provided between the inner arms 2 f the gripper fingers 1 . Fur- ther, the gripper device 15 comprises actuation means 21 arranged in connection with the connection point 20 and being on opposite side to the angle A for connecting the gripper device to an actuator . As shown in figure 4 , the whole gripper devil e may be a monolithic struc- ture .

[0058] Figure 5 shows a monolithic and elastic gripper finger for a gripper device having a monolithic elastic structure comprising an inside arm 2 having a f irst folding point 8 , forming an angle C, and an outside arm 3 . The inside arm 2 or the outside arm 3 compri ses a gripping surface for contacting an obj ect to be gripped . In figure 5 , the gripping surface 7 is at the inner arm and, thus , the obj ect is configured to be gripped with the inner arm . The gripper finger comprises a first base end 10 , from which the inside arm 2 is extending, and a second base end 11 , from which the outside arm 3 is extending . A tip portion 6 is provided at the end of the gripper f inger , where the end of the outside arm 3 and the end of the inside arm 2 are connected to each other . The gripper finger 1 comprises two support arms 5a, 5b between the inside arm and the outside arm so that the first support arm 5a is provided between the first folding point 8 and the second base end 11 of the outs ide arm 3 , and the second support arm 5b is provided between the f irst folding point 8 and the second folding point 9 . The gripper finger may comprise , as shown in figures , a first protrusion 12 extending from the first base end 10 in direction that dif fers from the inside arm direction .

[0059] Figure 6 shows a gripper device 15 comprising two gripper fingers 1 shown in figure 5 . With two or more gripper fingers , the gripper device is capable to grip an obj ect via elastic deformation . Each gripper finger comprises gripping surfaces 7 so that an open space for the obj ect to be gripped is arranged between the gripping surfaces ( as shown in figure 6 ) . Optionally, the gripping surfaces are facing outwards for gripping hollow or tubelike obj ects , whereby the gripping surfaces may be pushed towards the inner surfaces of the obj ect . Each of the gripping fingers comprises a first support arm 5a provided between the first folding point 8 and the outside arm 3 . In figure 6, the first support arm 5a is provided between the first folding point 8 and the second base end 11 of the outside arm 3 , and the second support arm 5b is provided between the first folding point 8 and the second folding point 9 . The gripper finger comprises a frame structure 14 in which the second base end 11 is fixed . Further, the gripper device 15 comprises a connection point 20 where the first base ends 10 are connected to each other so that an angle A is provided between the inner arms 2 of the gripper fingers 1 . Further, the gripper device 15 comprises actuation means 21 arranged in connection with the connection point 20 and being on opposite side to the angle A for connecting the gripper device to an actuator . As shown in figure 6 , the whole gripper device may be a monolithic structure .

[0060] Although the figures 2 , 4 and 6 show a gripper device comprising two gripper fingers , it should be noted that the gripper device may comprise more than two gripper fingers . For example , the gripper device may comprise three , four of five gripper fingers . The gripper fingers may be provided symmetrically or asymmetrically .

[0061] A gripper finger comprising the first base end may have a first protrusion extending to a direction that di f fers from the inside arm direction . The protrus ion may form part of the actuation means of the gripper device for connecting the gripper finger or gripper device to an actuator .

[0062] Although not shown in the figures , the gripper device may comprise an actuator connected to actuation means for pivoting the tip portions of the gripper fingers for gripping the obj ect . The actuator is configured to provide input force to the gripper device , and when connected to the actuation means , the input force is converted via elastic deformation of the gripper mechanism to corresponding gripping force by pivoting the tip portions of the gripper fingers towards each other or farther from each other . The input force may be pulling force , i . e . the actuator pulls the actuation means 21 towards the frame structure 14 causing the gripper device to close , or the input force may be pushing force , i . e . the actuator pushes the actuation means outwards of the frame structure 14 causing the gripper device to open .

[0063] As noted above , the gripper device may comprise an actuator as an input drive for the gripper mechanism . The actuator is integrated to the frame structure 14 so that the actuator does not move , in relation to the gripper device , in use . In one embodiment , the actuator is mounted to the frame structure 14 by screws and / or bolts . Further , the actuator is mounted to the gripper fingers at the first protrusion 12 . It may be mounted by screws , glue or by an axle which is part of the actuator and is arranged through a hole in the first protrusion 12 .

[0064] The actuator may be for example solenoid actuator . Due to its characteristics , the solenoid actuator works very fast . The gripper device with integrated solenoid actuator works so that an input voltage is applied to the solenoid actuator and then the electromagnets turn on and attract the first protrusion 12 by pulling it down causing the gripper device to close. As long as the solenoid actuator is powered, the gripper device is closed, and possible object is held with certain holding force. When the input voltage for the solenoid actuator is turned off, the gripper device will return to its initial undeformed state, i.e. open position, as described earlier.

[0065] However, according to some embodiments, the actuator may be other kind of actuating device, which causes input drive for the gripper mechanism, such as electro-motor, pneumatic or hydraulic cylinders, or smart materialbased actuators, or other type of linear motors or rotary motors with additional elements to transform the rotation to needed linear actuating motion.

[0066] In one embodiment, the actuator is mounted to the first base end 10 of each gripper finger. However, in some embodiments the gripper fingers comprise a first protrusion 12 in which the actuator is mounted. In gripper device comprising several gripper fingers, the first protrusion 12 may be shared by the gripper fingers, wherein all three gripper fingers share a same first protrusion forming the actuation means described earlier, which is connected to or integral structure of the first base ends of each of the gripper fingers.

[0067] Although not shown in figures, each gripper finger and, thus, the gripper device, may have many different optional structures. For example, each gripper finger may have additional support arms provided between the inside arm and the outside arm, e.g. between the first base end 10 and the second folding point 9.

[0068] Optionally, the angle formed to the inside arm at the first folding point may be less than 180 degrees, 180 degrees (straight arm) or more than 180 degrees. Each variation has a different purpose in grasping.

[0069] Optionally, the outside arm may be straight, i.e. without any folding points, as shown in figures 1 and 2.

[0070] According to one embodiment, the monolithic elastic structure of the gripper finger is made of plastic material as it is very suitable, elastic and works well with wide variety of objects. According to some other embodiments the gripper finger may be made of thin metal sheet or rubber like silicone-based rubber material or any elastic-based materials.

[0071] Optionally, the whole gripper device is made of elastic material. According to one embodiment the material is plastic material due to its favorable characteristics. According to some other embodiments, the material may be for example thin sheet metal, rubber or silicone- based rubber material or some other elastic material.

[0072] Optionally, there is a support arm between the first folding point 8 and the second folding point 9, as seen in figures. Optionally, the first base end 10 and the second base end 11 are connected to each other by a support arm.

[0073] The operation of the gripper device may be described as follows: actuating an input force to the adaptive gripper device independent from the object, converting the input force via elastic deformation of the gripper mechanism to corresponding gripping force, and gripping the object via stored deformation energy of the gripper device in combination with the input force.

[0074] In more detail, the input force (and motion) is transmitted by the compliant structure of the gripper device to the output port (tip portions 6 of the gripper fingers 1) , but also to the gripping surface of the gripper device. In other words, the closing of the gripper fingers is realized due to elastic deformation of the gripper structure. One part of the input force is spent on the deformation of the elastic structure, but other part of the input force is transmitted to the output ports (and gripping surface) and gripper can realize output holding forces. If any object is placed between gripper fingers, the gripper device would realize grasping of the object with certain holding force (depending on the intensity of the input force) . But because the elasticity of the gripper device, the gripper fingers will in some cases conform to the shape of the object. Or, if the object is soft, it would not break the object (again due to compliance of the gripper fingers) but still would be able to effectively realize grasping. Thus, the gripper device realizes grasping of wide variety of objects with different shapes and especially soft and easily squeezably objects (like fruits or vegetables) or fragile objects (like light bulbs or eggs) . Further, due to elastic structure of the gripper device, there is no need for controlling the grasping force, i.e. just input force is applied and there is no need to control the force that the gripper fingers exert on an object. The gripper fingers rather deform or adapt to the object shape. By holding the gripper device in the deformed state, the gripper device will be closed, and the object is held. When the input force is released, i.e. the input force is no longer applied at the input port, the gripper device will open and return to its initial, undeformed state (position where the gripper fingers are open) of its own volition. This is due to the stored deformation energy, i.e. energy that is stored within the deformed segments of the gripper device so when the input force is released, the energy is released and the gripper device returns to its initial undeformed state. In a way, the gripper device behaves li ke a spring and it has built-in restoring force and, thus , no return force is needed . Although the invention has been described in conj unction with a certain type of device , it should be understood that the invention is not limited to any certain type of device . While the present inventions have been described in connection with a number of exemplary embod- iments , and implementations , the present inventions are not so limited, but rather cover various modi fications , and equivalent arrangements , which fall within the purview of prospective claims .

Claims

CLAIMS1. A gripper finger (1) for a gripper device having a monolithic elastic structure comprising- an inside arm (2) having a first folding point (8) forming an angle C,- an outside arm (3) , wherein the inside arm (2) or the outside arm (3) comprises a gripping surface (7) for contacting an object to be gripped,- a first base end (10) , from which the inside arm (2) is extending, and a second base end (11) , from which the outside arm (3) is extending,- a tip portion (6) where the end of the outside arm (3) and the end of the inside arm (2) are connected to each other, and- at least one support arm between the inside arm (2) and the outside arm (3) , c h a r a c t e r i z e d in that- a first support arm (5a) is provided between the first folding point (8) and the outside arm (3) .

2. A gripper finger according to claim 1, wherein the first support arm (5a) is provided between the first folding point (8) and the second base end (11) •3. A gripper finger according to claim 1, wherein the outer arm comprises a second folding point (9) , and the first support arm (5a) is provided between the first folding point (8) and the second folding point (9) .

4. A gripper finger according to claim 1, wherein the first support arm (5a) is provided between the first folding point (8) and the second base end (11) and a second support arm (5b) is provided between thefirst folding point (8) and the second folding point (9) .

5. A gripper finger according to claim 1, wherein the first base end (10) comprises a protrusion extending to a direction that differs from the inside arm (2) direction.

6. An adaptive gripper device (15) comprising at least two gripper fingers according to any of the preceding claims ,- the gripper fingers (1) are monolithic elastic structures arranged to grip an object via elastic deformation, and- the gripping surfaces (7) of the gripping fingers (1) are facing each other so that an open space for the object to be gripped is arranged between the gripping surfaces (7) , or the gripping surfaces (7) are facing outwards whereby gripping surfaces may be pushed towards the inner surfaces of the object, c h a r a c t e r i z e d in that a first support arm (5a) is provided between the first folding point (8) and the outside arm (3) .

7. An adaptive gripper device according to claim 6, wherein the gripper device (15) comprises a frame structure (14) in which the second base ends (11) are fixed.

8. An adaptive gripper device according to claim 7, wherein device comprises a connection point (20) where the first base ends of the gripper fingers are connected to each other so that an angle A is provided between the inner arms of the gripper fingers.

9. An adaptive gripper device according to claim 8, wherein the device comprises actuation means (21) arranged in connection with the connection point and beingon opposite side to the angle A for connecting the gripper device to an actuator.

10. An adaptive gripper device according any one of claims 6 or 9, wherein the whole gripper device (15) is a monolithic structure .

11. An adaptive gripper device according to any of claims 7 to 10, characterized in that the gripper device (15) comprises an actuator (16) connected to actuation means for pivoting the tip portions (6) of the gripper fingers for gripping the object.

12. An adaptive gripper device according to claim 11, characterized in that the actuator (16) is arranged to pivot the tip portions (6) of the gripper fingers farther from each other.

13. An adaptive gripper device according to claim 11 or 12, characterized in that the actuator (16) is a solenoid actuator .

14. A method for gripping an object with an adaptive gripper device according to any of claims 6 to 13 comprising steps of- actuating an input force to the adaptive gripper device independent from the object,- converting the input force via elastic deformation of the gripper mechanism to corresponding gripping force, and- gripping the object via stored deformation energy of the gripper device in combination with the input force .

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