NL2013592B1

NL2013592B1 - Mechanical end effector.

Info

Publication number: NL2013592B1
Application number: NL2013592A
Authority: NL
Inventors: Edward Aguirre Milton Jr
Original assignee: Univ Delft Tech
Priority date: 2014-10-08
Filing date: 2014-10-08
Publication date: 2016-10-03

Abstract

Mechanical end effector (1) comprising at least two movable parts (4, 5), wherein each of the movable parts (4 resp. 5) is mounted on at least two supports (6, 6' resp. 7, 7'), wherein a relative position of the movable parts (4, 5) with respect to each other is variable by changing the relative position of the supports (6, 6'; 7, 7') with respect to each other, and wherein the supports (6, 6'; 7, 7') of the movable parts (4, 5) comprise bendable members, wherein the bendable members are equipped with mechanical properties that arrange for flexing of the bendable members when a force applied by the supports (6, 6'; 7, 7') of the movable parts (4, 5) exceeds a predefined value.

Description

Mechanical end effector

The invention relates to a mechanical end effector comprising at least two movable parts, wherein each of the movable parts is mounted on at least one support, wherein a relative position of the movable parts with respect to each other is variable by changing the relative position of the supports with respect to each other, and wherein the supports of the movable parts comprise bendable members. Usually the supports of the two movable parts share a common base or base structure .

Such a mechanical end effector wherein each of the movable parts is mounted on two supports appears to be disclosed in figure 6 of W003/026519, although this is far from certain considering the obscure discussion of this figure on page 6 of this citation's description. Considering that figure 6 of W003/026519 bears resemblance with the figures that are attached hereto to elucidate the invention, it is assumed that particular features as provided in the preamble of the main claim are common to the invention and the prior art. A mechanical end effector can for instance be embodied as a gripper or a cutter, and may be in use in robotics or surgical applications, particularly in minimal invasive surgery. One of the problems in using a mechanical end effector that is particularly bothersome in robotics and surgical applications is the lack of sensitivity of the effector in terms of forces that may be applied to an object. A further problem is its lacking capability to provide its user of haptic feedback on the forces that are applied with the effector on an object which is to be manipulated or cut. This is particularly problematic in surgical applications.

It is one of the objectives of the invention to provide a solution or at least an improvement regarding the problem of lacking sensitivity and the problem of lacking feedback for the user.

The mechanical end effector of the invention is provided with one or more of the features according to the appended claims.

In a first aspect of the invention the bendable mem- bers of the mechanical end effector are equipped with mechanical properties that arrange for flexing of said members when a force applied by the supports of the movable parts exceeds a predefined value. This is beneficial since the flexing of the bendable members not only limits the forces that the movable parts exercise on an object, but also provides a visual feedback to a user which can be tailored to the amount of force with is acceptably applied to the object. Appropriately therefore the predefined value is within a range of usual forces that are applied when the effector is used for gripping or grasping an object.

The mechanical end effector according to the invention is suitably arranged such that each of the bendable members is embodied as a pair of cooperating bands predominantly running parallel in an unloaded situation from a base or base structure to the movable part that the bands support.

Beneficially the cooperating bands of a pair of cooperating bands run to the movable part in an unloaded situation at a predefined distance from each other so as to provide room for bending of at least one band of said pair of cooperating bands. The room between the cooperating bands is very instrumental in enabling suitable bending of at least one of the bands thus facilitating both a limitation of the forces that may be applied with the movable parts on an object, as well as providing effective means of visual feedback to a user that applies the forces to the movable parts.

The invention will hereinafter be further elucidated with reference to the drawing of an exemplary embodiment of an apparatus according to the invention that is not limiting as to the appended claims.

In the drawing: -figure 1 shows a mechanical grasper provided with a mechanical end effector according to the invention; -figure 2, 3 and 4 show a sequence of events that occur when the mechanical end effector of figure 1 is used to grab an object.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

Making reference first to figure 1 the mechanical end effector of the invention is indicated with reference 1. This mechanical end effector 1 is for exemplary purposes mounted at a distal side of a rod 2 which has on its proximal side a handle 3 which may be used for opening and closing the mechanical end effector 1. The mechanical end effector 1 of this ex emplary embodiment comprises two movable parts 4, 5. The movable part 4 is mounted on two cooperating supports 6, 6', whereas the movable part 5 is mounted on two cooperating supports 7, 1'. The supports 6, 6', 7, 7' of the two movable parts 4, 5 further share a common base or base structure 8. It is remarked however that the invention is also applicable to a construction in which both the movable part 4 and the movable part 5 are each individually mounted on a single support. This is immediately clear to the skilled person and requires no further elucidation with reference to a drawing.

Figures 2, 3, and 4 show in detail the mechanical end effector 1 shown in figure 1 when the effector is used to grasp an object 9.

Figure 2 shows the situation that the mechanical end effector 1 is in the vicinity of the object 9 which is intended to be grabbed by the mechanical end effector 1. To enable this the mechanical end effector 1 is construed such that a relative position of the movable parts 4, 5 with respect to each other is variable. Movement of movable part 4 is done by changing the relative position of the supports 6, 6' of movable part 4 with respect to each other. Movement of movable part 5 is done by changing the relative position of the supports 7, 7' of movable part 5 with respect to each other.

The supports 6, 6' and Ί, 1' of the movable parts 4, 5 comprise or are embodied as bendable members. The bendable members are equipped with mechanical properties that arrange for flexing of the bendable members when a force applied by the supports 6, 6' and 1, 1' of the movable parts 4, 5 exceeds a predefined value. The flexing of the bendable members can beneficially be used to provide a visual feedback to a user. The flexing of the bendable members arranges that when the movable parts 4, 5 engage the object 9 as shown in figure 3, a certain degree of deformation occurs of each of the bendable members embodying the supports 6, 6' and 7, 7'. By further in creasing the actuation forces applied to the supports 6, 6' and 7, 7' eventually the situation emerges as shown in figure 4. Here the largest degree of deformation of the bendable members embodying the supports 6, 6' and 7, 7' is depicted.

One of the advantages of arranging that the supports 6, 6' and 7, 7' of the movable parts 4, 5 comprise or are embodied as bendable members is that a force applied by the supports 6, 6' and 7, 7' to the movable parts 4, 5 is limited to a well defined pre-established value which is determined by properly selecting the mechanical properties of the bendable members .

In the exemplary embodiment depicted in the figures each of the bendable members is embodied as a pair of cooperating bands 10, 11 and 12, 13, which in the unloaded situation shown in figure 2 predominantly run parallel from the base or base structure 8 to the movable part 4, 5 the bands support. The cooperating bands 10, 11 respectively 12, 13 of a pair of cooperating bands run to the concerning movable part 4, 5 in the unloaded situation at a predefined distance from each other so as to provide room for bending of at least one band of said pair of cooperating bands 10, 11 and 12, 13. This is clearly illustrated in figure 4.

Although the invention has been discussed in the foregoing with reference to an exemplary embodiment of the mechanical end effector of the invention, the invention is not restricted to this particular embodiment which can be varied in many ways without departing from the gist of the invention. The discussed exemplary embodiment shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiment is merely intended to explain the wording of the appended claims without intent to limit the claims to this exemplary embodiment. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using this exemplary embodiment.

Claims

1. Mechanical end effector (1) comprising at least two movable parts (4, 5), wherein each of the movable parts (4 resp. 5) is mounted on at least one support (6, 6' resp. 7, 7'), wherein a relative position of the movable parts (4, 5) with respect to each other is variable by changing the relative position of the supports (6, 6'; 7, 7') with respect to each other, and wherein the supports (6, 6'; 7, 7') of the movable parts (4, 5) comprise bendable members, characterized in that the bendable members are equipped with mechanical properties that arrange for flexing of said members when a force applied by the supports (6, 6'; 7, 7') of the movable parts (4, 5) exceeds a predefined value.

2. Mechanical end effector (1) according to claim 1, characterized in that the predefined value is within the range of usual forces that are applied when the effector is used for gripping or grasping an object.

3. Mechanical end effector (1) according to claim 1 or 2, characterized in that the flexing of the bendable members provides for a visual feedback to a user.

4. Mechanical end effector (1) according to any one of claims 1-3, characterized in that each of the bendable members is embodied as a pair of cooperating bands (10, 11; 12, 13) predominately running parallel in an unloaded situation from a base or base structure (8) to the movable part (4; 5) that the bands support.

5. Mechanical end effector according to claim 4, characterized in that the cooperating bands (10, 11 resp. 12, 13) of a pair of cooperating bands run in an unloaded situation to the movable part (4; 5) at a predefined distance from each other so as to provide room for bending of at least one band of said pair of cooperating bands (10, 11; 12, 13).