Patent Description:
A gripper is one important type of end effector of a robot. Grippers can be utilized to catch or release an external object. Typically, a driving component (e.g., an air cylinder) may be utilized to drive the gripper and to provide a constant force for holding the object during the movement of the robot. However, if the force of the gripper is too strong, the external object may be damaged. Thus, it is important to detect the force applied to the external object so as to adjust the driving component properly.

<CIT> discloses an end effector having a plurality of digits, each of which is rotatable and maneuverable to enable grasping. A drive shaft for each digit is axially movable in response to substantial loads on the digit against the resistance of a compressive strain spring. A Hall Effect sensor determines the load on a digit by measuring the axial movement.

The present disclosure provides a gripper of robot and a robot in order to detect the force applied on the object grasped by the gripper. In one embodiment, a gripper of a robot is provided, comprising a case, a plurality of fingers rotatably connected to the case, and a plurality of connecting rods. A first end of each of the connecting rods may be connected to a respective one of the plurality of fingers. The gripper may further comprise a driving assembly connected to a second end of each of the connecting rods, and configured to drive the second end of each of the connecting rods to move along a moving direction so as to drive the plurality of fingers to rotate. The gripper may also include a force detecting assembly connected to the case and the driving assembly, and configured to limit a position of the driving assembly along the moving direction and to detect a force from the driving assembly.

In another embodiment, the driving assembly comprises a nut connected to the second end of each of the connecting rods, a lead screw penetrating through the nut and reciprocally coupled with the nut, and a driving component connected to the lead screw and configured to rotate the lead screw so as to move the nut and the second end of each of the connecting rods along the moving direction. The force detecting assembly may be connected to at least one of the lead screw and the driving component.

In yet another embodiment, the force detecting assembly comprises a connecting plate rotatably connected to the lead screw, wherein the connecting plate is fixed with the lead screw along the moving direction and a force sensor connected to the case and the connecting plate, and configured to detect an axial force applied to the connecting plate by the lead screw.

In a further embodiment, the connecting plate is connected to the lead screw through a rolling bearing capable of transmitting axial and radial forces.

In a still further embodiment, the force sensor includes one or more of a tension sensor, a pressure sensor, and a tension and pressure sensor.

In another embodiment, a first end of the lead screw is rotatably and slidably connected to the case to constitute a sliding pivot pair and a second end of the lead screw is slidably connected to a driven end of the driving component to constitute a sliding pair.

In a further embodiment, the force detecting assembly comprises a connecting plate on which the driving component is installed and a force sensor fixedly connected to the case and the connecting plate and configured to detect an axial force applied by the driving component on the connecting plate.

In yet another embodiment, the driving component is a motor.

In a still further embodiment, the driving assembly comprises a support connected to the second end of each of the connecting rods, a motor installed on the support, where a pinion is set on a driven end of the motor, and a gear rack assembly comprising a housing and a gear rack. The housing may be slidably connected to the case along the moving direction, the gear rack may extend along the moving direction and may engage with the pinion, and the force detecting assembly may abut against the housing to limit a position of the housing along the moving direction.

In a further embodiment, a robot adapted to catch an object is provided, comprising any of the grippers as described above.

To more clearly explain the technical solutions in the embodiments of the present disclosure, the drawings used in the description of the embodiments will be briefly described below. The drawings in the following description are merely exemplary embodiments of the present disclosure. For those of ordinary skill in the art, other drawings may also be obtained based on these drawings without any creative work.

<FIG> is a structural diagram of a gripper <NUM> of a robot according to an exemplary embodiment of the present disclosure. The gripper <NUM> includes a case <NUM>, multiple fingers <NUM>, multiple connected rods <NUM>, a driving assembly <NUM>, and a force detecting assembly <NUM>. The gripper <NUM> may be utilized as an end effector of a robot, e.g., an articulated robot. The gripper <NUM> may be coupled with a plurality of robotic arms and may have multiple degrees of freedom for movement. The structure of the arms or other components of the robot may refer to related art and will not be discussed herein.

The case <NUM> of the gripper <NUM> may be made of metal material, non-metal material or composite material, such as aluminum, aluminum alloy, steel, carbon fiber reinforced composite and the like. The case <NUM> may define an accommodating space (not shown) for receiving other components. The case <NUM> may be a closed or sealed structure by sufficient means (e.g., rubber or similar seals) so as to protect the components disposed inside the case <NUM> from water and dust.

The fingers <NUM> may be made of the same or a different material as compared with the case <NUM>, so long as the fingers <NUM> have enough structural strength for catching and holding an external object <NUM>. Each finger <NUM> is rotatably connected to the case <NUM>. For example, one end of the finger <NUM> may connect to the case <NUM> through a pivot <NUM>. Accordingly, the other portion of the finger <NUM> may rotate with respect to the case <NUM> about the pivot <NUM>. In order to achieve the catching function, the number of the fingers <NUM> may be equal to or larger than two. In the example shown in <FIG>, two fingers <NUM> are shown merely for illustrative purpose.

The connecting rods <NUM> are connected between the driving assembly <NUM> and the fingers <NUM>. Specifically, a first end of each connecting rod <NUM> may be fixedly connected to a respective finger <NUM> such that the connecting rod <NUM> may rotate in accordance with the finger <NUM>. A second end of the connecting rod <NUM> is connected with the driving assembly <NUM>, and the driving assembly <NUM> is utilized to drive the second end of each connecting rod <NUM> to move along a moving direction (i.e., in the first direction or in the second direction opposite to the first direction, as shown in <FIG>). Accordingly, the movement of the connecting rod <NUM> may lead to the movement of the finger <NUM>. That is, the connecting rod <NUM> may convert the rotational motion of the finger <NUM> into linear motion of the driving assembly <NUM> along the determined moving direction. It should be understood that, for achieving this function, the connecting rod <NUM> may include several sub-rods. The number of the sub-rods of one connecting rod <NUM> may be two or more, which is not limited in the present disclosure (e.g., alternative implementations may include more than two sub rods). For example, in the depicted embodiment, the connecting rod <NUM> may include a first sub-rod <NUM> and a second sub-rod <NUM>. One end of the first sub-rod <NUM> is fixedly connected with the finger <NUM>, while the other end of the first sub-rod <NUM> is rotatably connected with one end of the second sub-rod <NUM>. Moreover, the other end of the second sub-rod <NUM> may be rotatably connected to the driving assembly <NUM>. Thus, the linear motion of the portion of the driving assembly <NUM> may drive the second sub-rod <NUM> and the first sub-rod <NUM> to rotate and thereby cause the rotational motion of the finger <NUM>. The driving assembly <NUM> may include any driving apparatus capable of providing linear driving force. For example, the driving assembly <NUM> may include a motor, a lead screw and a nut, or may include a motor, a gear rack and a pinion, or the driving assembly <NUM> may correspond to an air/liquid cylinder. The detailed structure of the driving assembly <NUM> will be discussed further below.

In some embodiments, the finger <NUM> may be disposed on the outside of the case <NUM>, while the connecting rod <NUM> may be disposed on the inside of the case <NUM>, as shown in <FIG>. Thus, the finger <NUM> may be utilized to catch the external object <NUM> outside the case <NUM>, and the connecting rod <NUM> and the driving assembly <NUM> connected to the connecting rod <NUM> may be shielded inside the case. In such circumstances, the finger <NUM> and the connecting rod <NUM> may be connected through a shaft of the pivot <NUM> which extends through the case <NUM>. The pivot <NUM> may be well sealed to prevent dust and water from entering. In other embodiments, as shown in <FIG>, a portion of the finger <NUM> may also be disposed inside the case <NUM> together with the connecting rod <NUM>. In such implementations, the end portion of the finger <NUM>, located away from the connecting rod <NUM>, may extend outside the case <NUM> through a slot (not shown) of the case <NUM> for catching an external object.

The force detecting assembly <NUM> is connected to both the case <NUM> and the driving assembly <NUM>. Although not shown in the figures, those of ordinary skill should understand that the force detecting assembly <NUM> may be installed on the inside of the case <NUM> by any suitable methods such as welding, clamping or screwing. The force detecting assembly <NUM> is utilized to limit the position of the driving assembly <NUM> along the moving direction. Since the driving assembly <NUM> is free to move relative to the case <NUM> along the moving direction and the second end of the connecting rod <NUM> may move along the moving direction under the driving force provided by the driving assembly <NUM>, any counter-acting force applied to the second end of the connecting rod <NUM> on the driving assembly <NUM> which lies in the moving direction is applied onto the force detecting assembly <NUM>. Accordingly, by detecting this counter-acting force, the force detecting assembly <NUM> also detects the driving force applied by the driving assembly <NUM> onto the second end of the connecting rod <NUM>. Thus, the force applied by the fingers <NUM> onto the external object <NUM> may be calculated based on force and/or moment balance principle.

According to the present disclosure, as the driving assembly <NUM> is connected to the second end of each connecting rod <NUM> while the first end of each connecting rod <NUM> is fixedly connected to one finger <NUM> of the gripper <NUM>, the rotation of the fingers <NUM> of the gripper <NUM> may be driven by the driving assembly <NUM>. Moreover, since the driving assembly <NUM> is limited by the force detecting assembly <NUM> in the moving direction of the second end of each connecting rod <NUM>, the force detecting assembly <NUM> may detect the force from the driving assembly <NUM>. With this force, the grasping force of the gripper <NUM> may be calculated. Such implementations may be utilized to determine the force applied on the grasped object <NUM>, thereby improving the control of the gripper <NUM> and the robot.

In some embodiments, the driving assembly <NUM> of the gripper <NUM> may include a nut <NUM>, a lead screw <NUM>, and a driving component <NUM>. The nut <NUM> may be rotatably connected to the second end of each connecting rod <NUM>. The lead screw <NUM> may penetrate through the nut <NUM> and reciprocally couple with the nut <NUM>. That is, when the lead screw <NUM> rotates, the nut <NUM> moves in the moving direction, and vice versa. The driving component <NUM> may be connected to the lead screw <NUM> and may be configured to rotate the lead screw <NUM> such that the second end of each connecting rod <NUM> together with the nut <NUM> may be capable of movement along the moving direction. The driving component <NUM> may be any device capable of rotating the lead screw <NUM>, for example, the driving component <NUM> may be a motor. In this embodiment, the force detecting assembly <NUM> may be connected to either the lead screw <NUM> or the driving component <NUM>. Those of ordinary skill should understand that, in order to improve the stability of the gripper <NUM>, when the lead screw <NUM> is connected to the force detecting assembly <NUM>, the driving component <NUM> may be slidably connected to the case <NUM> to constitute a sliding pair along the moving direction, and vice versa.

Continuing to refer to <FIG>, in some embodiments, the force detecting assembly <NUM> may include a connecting plate <NUM> and a force sensor <NUM>. The connecting plate <NUM> may be rotatably connected to the lead screw <NUM> by means of, for example, a rolling bearing (not labeled) capable of transmitting both radial and axial forces. Thus, the counter-acting force applied by the nut <NUM> on the lead screw <NUM>, i.e., the axial force on the lead screw <NUM>, may be transmitted through the rolling bearing to the force sensor <NUM> and may be measured by the force sensor <NUM>.

In this embodiment, the force sensor <NUM> may correspond to a tension sensor, a pressure sensor, or a tension and pressure sensor according to actual design requirements. For example, in the embodiment shown in <FIG>, when the lead screw <NUM> drives the nut <NUM> to move in the first direction, the fingers <NUM> may be clasped and may catch the external object <NUM>. In this situation, the force sensor <NUM> may be a pressure sensor disposed on the lower side (as shown in <FIG>) of the connecting plate <NUM> to support the connecting plate <NUM> and to block the connecting plate <NUM> from continuing to move in the first direction. Alternatively, the force sensor <NUM> may be a tension sensor disposed on the upper side (not shown) of the connecting plate <NUM> to pull the connecting plate <NUM> and also to block the connect plate <NUM> from continuing to move in the first direction.

In some embodiments, a first end <NUM> of the lead screw <NUM> (e.g., the upper end as shown in <FIG>) may be rotatably and slidably connected to the case <NUM> to constitute a sliding pivot pair through, for example, a rolling bearing (not labeled) which is capable of transmitting radial force only. In this way, the case <NUM> or the rolling bearing may not limit the axial position of the lead screw <NUM> but may still fix the lead screw <NUM> at its radial position. It should be understood, in some embodiments, the connecting plate <NUM> may be connected to the first end <NUM> of the lead screw <NUM> rather than being connected to a middle portion of the lead screw <NUM>. In such implementations, the connecting plate <NUM> and the force sensor <NUM> may be configured to provide radial and axial support for the lead screw <NUM>, and thus the rolling bearing which transmits only radial force may be omitted.

In some embodiments, as shown in <FIG> and <FIG>, the second end <NUM> of the lead screw <NUM> (e.g., the lower end as shown in <FIG>) may be slidably connected to a driven end <NUM> of the driving component <NUM> to constitute a sliding pair. Specifically, as shown in <FIG>, the driven end <NUM> of the driving component <NUM> may define a slot (not labeled) extending substantially perpendicular to the axial direction (i.e., the moving direction) of the lead screw <NUM>. The second end <NUM> of the lead screw <NUM> may include a limit block (not labeled) extending along the same direction as the slot. The limit block may be received in the slot and may move in the axial direction of the lead screw <NUM> in a certain range. However, the limit block may not be capable of rotating with respect to the driven end <NUM>. The driving component <NUM> and the limit block may thus drive the lead screw <NUM> to rotate without having to support the lead screw <NUM> along its moving direction.

<FIG> is a structural diagram of a gripper <NUM> of a robot according to another embodiment of the present disclosure. The gripper <NUM> may include a case <NUM>, multiple fingers <NUM>, multiple connecting rods <NUM>, a driving assembly <NUM>, and a force detecting assembly <NUM>. The driving assembly <NUM> may include a nut <NUM>, a lead screw <NUM>, and a driving component <NUM>. The force detecting assembly <NUM> includes a connecting plate <NUM> and a force sensor <NUM>. The structure of the gripper <NUM> is similar to the gripper <NUM> described above. However, for the gripper <NUM>, the driving component <NUM> may be installed on the connecting plate <NUM>, and configured to detect an axial force applied by the driving component <NUM> onto the connecting plate <NUM>. The lead screw <NUM> may be connected to the driven end of the driving component <NUM> by a mechanism capable of transmitting axial force, e.g., a thrust bearing. Thus, the force applied by the nut <NUM> on the lead screw <NUM> may be transmitted to the connecting plate <NUM> and the force sensor <NUM>. Therefore, the force sensor <NUM> of the force detecting assembly <NUM> may measure the force so as to calculate the force applied on an external object.

<FIG> is a structural diagram of a gripper <NUM> of robot according to another embodiment of the present disclosure. The gripper <NUM> of this embodiment may include a case <NUM>, multiple fingers <NUM>, multiple connecting rods <NUM> similar to the gripper <NUM> or the gripper <NUM> described above. However, the gripper <NUM> may further include a driving assembly <NUM> and a force detecting assembly <NUM>. The driving assembly <NUM> may include a support <NUM>, a motor <NUM> and a gear rack assembly <NUM>. The support <NUM> may be fixedly connected to the second end of each of the connecting rods <NUM>. The motor <NUM> may be installed on the support <NUM>, and a pinion <NUM> may be set on the driven end of the motor <NUM>. The gear rack assembly <NUM> may include a housing <NUM> and a gear rack <NUM> arranged on the housing <NUM>. The housing <NUM> may be slidably connected to the case <NUM> along the moving direction of the second end of the connecting rods <NUM>. The gear rack <NUM> may also extend along said moving direction and may be engaged with the pinion <NUM>. Moreover, the force detecting assembly <NUM> may abut against the housing <NUM> so as to limit a position of the housing <NUM> along the moving direction. In this embodiment, the motor <NUM> may drive the pinion <NUM> to rotate. As the pinion <NUM> is engaged with the gear rack <NUM> arranged on the housing <NUM> which is supported by the force detecting assembly <NUM> along the moving direction, the pinion <NUM> may drive the motor <NUM> together with the support <NUM> in return to move along said moving direction of the second end of the connecting rods <NUM>. Thus, the fingers <NUM> of the gripper <NUM> may be clasped to hold an external object, and the force detecting assembly <NUM> may measure the feedback force from the housing <NUM>.

The present disclosure also provides a robot adapted to catch an object. The robot may include one or more gripper as described in any one of the above-described embodiments.

Claim 1:
A gripper of a robot, comprising:
a case (<NUM>, <NUM>, <NUM>);
a plurality of fingers (<NUM>, <NUM>, <NUM>) rotatably connected to the case (<NUM>, <NUM>, <NUM>);
a plurality of connecting rods (<NUM>, <NUM>, <NUM>), wherein a first end of each of the connecting rods (<NUM>, <NUM>, <NUM>) is connected to a respective one of the plurality of fingers (<NUM>, <NUM>, <NUM>);
a driving assembly (<NUM>, <NUM>, <NUM>) connected to a second end of each of the connecting rods (<NUM>, <NUM>, <NUM>), and configured to drive the second end of each of the connecting rods (<NUM>, <NUM>, <NUM>) to move along a moving direction so as to drive the plurality of fingers (<NUM>, <NUM>, <NUM>) to rotate; and
a force detecting assembly (<NUM>, <NUM>, <NUM>) connected to the case (<NUM>, <NUM>, <NUM>) and the driving assembly (<NUM>, <NUM>, <NUM>), and configured to detect a force from the driving assembly (<NUM>, <NUM>, <NUM>),
characterised in that:
the force detecting assembly (<NUM>, <NUM>, <NUM>) is further configured to limit a position of the driving assembly (<NUM>, <NUM>, <NUM>) along the moving direction.