Patent Description:
Robots and robotic assistants configured to replace and/or assist humans are proliferating and engage in an ever expanding variety of applications from relatively simple pick and place tasks, serving coffee in paper cups, to carrying out surgeries on the human body. Almost invariably the tasks involve gripping, moving, and often using different types of objects that the human hand under control of hand-eye coordination and haptic feedback carries out gracefully with seemingly little effort.

<CIT> describes a robotic mechanical manipulator comprising a gripper, referred to as an "end effector", operable to grip and vibrate a container to shake out contents of the container. US Patent Publication <CIT> disclose a robot hand operable to contact and transmit vibrations though the object to classify the object. French Patent Publication <CIT> discloses a robotic finger attached to a portable device to provide a haptic interface to the device.

Providing robotic fingers and hands with a semblance of the natural abilities of the human hand is a challenging task of intricate complexity.

An aspect of an embodiment of the disclosure relates to providing an artificial or robotic finger for touching and holding an object and applying force substantially parallel to a contact surface region of the object to manipulate the object with relatively high spatial accuracy.

In an embodiment, the artificial finger, hereinafter also referred to as an "Accu-Finger", comprises a distal phalange housing a vibrator coupled to a contact pad configured to make frictional contact with the surface contact region at an extreme end of the phalange. The vibrator is excitable to generate vibratory motion along a vibration axis that is optionally fixed relative to the structure of the vibrator and is substantially perpendicular to an axis of the vibrator. In an embodiment the vibrator comprises an eccentric rotating mass (ERM) motor and the vibration axis is substantially parallel to a plane of rotation of the eccentric mass and passes through a center of rotation of the eccentric mass. During a first half, also referred to as a first phase, of each cycle of the vibratory motion the vibrator or a portion thereof moves in a first direction along the vibration axis. During a second half, also referred to as a second phase of the cycle, the vibrator or portion thereof moves in an opposite direction along the vibration axis. The excited vibrations of the vibrator induce corresponding vibrations of the contact pad substantially along the same vibration axis along which the vibrator vibrates.

When the contact pad is pressed to the contact surface region of the object and the vibrator excited to vibrate, during the first phase of each vibration cycle frictional force between the contact pad and the surface region substantially sticks and holds the contact pad to the contact surface region and the contact pad applies force to the contact surface region that operates to accelerate and/or move the object in the first direction along the vibration axis. During the second phase of the vibration cycle, frictional force between the contact pad and the surface region decreases,the contact pad slips along the contact surface, and force applied to the contact surface region is less than during the first phase of the vibration cycle. As a result, the vibration cycle operates to generate a net translation of the contact surface region of the object in the first direction along the vibration axis. For convenience of presentation, the first phase of the vibratory motion of the contact pad in which the contact pad sticks to the contact surface of the object may be referred as a sticking phase. The second phase may be referred to as a slipping phase.

The vibrator is connected to a transmission system operable to rotate the vibrator and thereby the vibration axis along which the vibrator and contact pad execute vibratory motion, to a desired azimuth angle about the vibrator axis. The transmission system may comprise a shaft connected to the vibrator and to a transmission motor and has a transmission axis that is optionally substantially coincident with the vibrator axis. The transmission motor is controllable to rotate the shaft to a desired azimuth angle about the vibrator axis and thereby to orient the vibrator and axis of vibration in an azimuthal direction along which it is desired to have the contact pad apply force to and move the object. In an embodiment, the distal phalange is coupled to a medial phalange that houses the transmission motor.

In an embodiment, at least one Accu-Finger is coupled to an opposing finger to form a gripper, also referred to as an Accu-Gripper, operable to grip an object between the Accu-Finger and the opposing finger and control the at least one Accu-finger to manipulate the gripped object. Optionally, the opposing finger is an Accu-Finger.

In an embodiment, a plurality of Accu-Fingers are coupled to an opposable thumb to provide a robotic hand, also referred to as an Accu-Hand, that mimics human hand motion to grasp and manipulate an object. Optionally, the opposable thumb is an Accu-Finger.

Non-limiting examples of embodiments of the disclosure are described below with reference to figures attached hereto that are listed following this paragraph. Identical features that appear in more than one figure may be labeled with a same label in multiple figures in which they appear. A label labeling an icon representing a given feature of an embodiment of the disclosure in a figure may be used to reference the given feature. Dimensions of features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale.

Wherever a general term in the disclosure is illustrated by reference to an example instance or a list of example instances, the instance or instances referred to, are by way of non-limiting example instances of the general term, and the general term is not intended to be limited to the specific example instance or instances referred to. Unless otherwise indicated, the word "or" in the description and claims is considered to be the inclusive "or" rather than the exclusive or, and indicates at least one of, or any combination of more than one of items it conjoins.

<FIG> schematically shows an Accu-Gripper <NUM>, having a Accu-Finger <NUM>, and a supporting finger <NUM>, hereinafter also referred to as an opposable finger <NUM>, oppositely disposed to the Accu-Finger <NUM>. Accu-finger <NUM> and opposable finger <NUM>, are shown by way of example, as gripping a disk <NUM>. Both Accu-Finger <NUM> and support finger <NUM> are movably connected to a palm <NUM>, to allow fingers <NUM> and <NUM> to be moved toward each other to grip disk <NUM> and away from each other to release the disk. Palm <NUM> comprises any configuration of linkages, actuators and/or motors controllable to move Accu-Finger <NUM> and opposable finger <NUM> to grip or release disk <NUM>.

Accu-Finger <NUM>, for example, includes three sections, a proximal phalange (phalanx) <NUM>, in communication with an intermediate phalange <NUM>, in communication with a distal phalange <NUM>. These three phalange sections <NUM>, <NUM>, <NUM>, may mimic the phalanges which form human fingers.

Distal phalange <NUM> includes a protrusion <NUM>, which terminates at a contact pad <NUM>. Contact pad <NUM> is configured to make frictional contact with articles, for example, with a surface contact region 106a of disk <NUM>. Accu-finger <NUM>, is operable to generate vibrations in contact pad <NUM> that apply force to disk <NUM>, parallel to surface 106a of the disk to displace the disk optionally in a direction indicated by a shaded region of an axis of vibration indicated by a double headed arrow <NUM>.

The shaded region points in a direction in which contact pad <NUM> moves during the sticking phase of the vibratory motion of contact pad <NUM>. The unshaded region points in a direction in which the contact pad moves during the slipping phase of the vibratory motion. During the sticking phase, motion of contact pad <NUM> operates to displace disk <NUM> in the direction of shaded region of vibration axis <NUM>. During the slipping phase of the vibratory motion contact pad <NUM> applies a smaller normal force to disk <NUM> than during the sticking phase and slips along the surface of the disk. As a result, the vibratory motion generally moves disk <NUM> in the direction of the shaded portion of the vibration axis. The control of the direction along the vibration axis <NUM> towards the shaded region is further elaborated below.

In an embodiment, proximal phalange <NUM> is rotatably mounted to a member 108a extending from palm <NUM> and to intermediate phalange <NUM>. Intermediate phalange <NUM> connects to distal phalange <NUM>. Intermediate phalange <NUM> is rotatably connected to an arm <NUM>, at one end thereof. The other end of arm <NUM> is rotatably connected to the palm.

Opposable finger <NUM>, for example, is optionally similar to Accu-Finger <NUM> and includes three sections, a proximal phalange <NUM>, in communication with an intermediate phalange <NUM>, which in turn communicates with a distal phalange <NUM>. The distal phalange includes a protrusion <NUM>, which terminates in a contact pad <NUM>. Contact pad <NUM> is configured to make contact with an object, for example, disk <NUM>, at a location opposite to that of a location at which contact pad <NUM> contacts the object when Accu-Finger <NUM> and opposable finger <NUM> are moved toward each other to grip the object.

For example, for opposable finger <NUM>, proximal phalange <NUM> is rotatably mounted to member 108b extending from palm <NUM> and to intermediate phalange <NUM>. Intermediate phalange <NUM> connects to distal phalange <NUM> and is rotatably connected to an arm <NUM> at one end thereof. The other end of arm <NUM> is rotatably connected to the palm. The linkages, actuators and/or motors of the palm may move member 108b and arm <NUM>, allowing for inward and outward movement of opposable finger <NUM>. The linkages, actuators and/or motors controllable to move Accu-finger <NUM> and opposable finger <NUM> may operate independently of each other, or in a cooperative manner.

<FIG> schematically shows a schematic see-thru view of distal phalange <NUM> to display internal components of the distal phalange in accordance with an embodiment of the disclosure. Phalange <NUM> houses a transmission system <NUM> that couples to a vibrator <NUM> via a shaft <NUM>, having an axis <NUM> which is a transmission axis of transmission system <NUM> and an axis of vibrator <NUM>. Transmission system <NUM> is operable to rotate vibrator <NUM> to a selected azimuth angle (Φ) about axis <NUM>, in accordance with an embodiment of the disclosure. When controlled to vibrate, vibrator <NUM> vibrates and generates vibratory motion of contact pad <NUM> back and forth along axis of vibration <NUM> (<FIG>). Vibration axis <NUM> is oriented to the selected azimuth angle to which transmission system <NUM> rotates vibrator <NUM> about axis <NUM>.

Transmission system <NUM> includes a motor <NUM>, coupled to a to rotate first bevel gear <NUM>, which intermeshes with a second bevel gear <NUM>. First and second bevel gears <NUM>, <NUM> intermesh to transfer rotational motion from first bevel gear <NUM> to second bevel gear <NUM>. Second bevel gear <NUM> couples to shaft <NUM>, which in turn, is coupled to vibrator <NUM>. Motor <NUM> is controllable to rotate first bevel gear <NUM> and thereby second bevel gear <NUM> and vibrator <NUM> about axis <NUM> selectively clockwise or counterclockwise.

Motor <NUM>, may for example, be a standard motor, which drives bevel gear <NUM>. Teeth 212a of the motor driven bevel gear <NUM>, engage and intermesh with a corresponding teeth 214a of bevel gear <NUM>, allowing for the transfer of rotational motion from motor driven bevel gear <NUM> to bevel gear <NUM>. Bevel gear <NUM> attaches to a collar <NUM>. The collar seats in a rotatable manner in a bearing <NUM>. Shaft <NUM> is attached to collar <NUM>, and extends through bevel gear <NUM>, collar <NUM>, and bearing <NUM>. Shaft <NUM> is, may for example, have a D-shaped cross section, formed, for example of a rounded portion 204a and a flat 204b, as shown in <FIG>. Flat 204b serves to lock bevel gear 214a to shaft <NUM>.

As also shown in <FIG>, a stop collar <NUM> receives shaft <NUM>. Shaft <NUM> and stop collar <NUM> seat in and rotate together in a second bearing <NUM>. Stop collar <NUM> includes a portion of larger diameter than the opening of second bearing <NUM> (through which shaft <NUM> and stop collar <NUM> extend) to prevent shaft <NUM> from moving axially in one direction. An optionally planar beam <NUM> having a normal "<NUM>" attaches stop collar <NUM> to vibrator <NUM>. Normal <NUM> may be substantially parallel to vibration axis <NUM>.

In an example operation of the Accu-Gripper <NUM>, as shown, for example in <FIG>, object <NUM> is initially held between Accu-Finger <NUM> and opposable finger <NUM>. Opposable finger <NUM> supports object <NUM> against Accu-Finger <NUM>, with contact pad <NUM> of opposable finger <NUM> advantageously substantially frictionless or characterized by substantially reduced friction. As noted above vibrator <NUM> is operable to vibrate in cycles, each cycle, including a first "forward" sticking phase and a second "rearward" slipping phase, along vibration axis <NUM> to move disk <NUM> in a forward direction indicated by of the shaded portion of arrow <NUM> shown in <FIG>.

For example, when contact pad <NUM> of Accu-Finger <NUM>, is pressed to contact surface region 106a of object <NUM>, and vibrator <NUM> is excited to vibrate, during the first sticking phase of each vibration cycle, static frictional force between contact pad <NUM> and contact surface region 106a of object <NUM> sticks and locks contact pad <NUM> to contact surface region 106a. Contact pad <NUM> applies force to the contact surface region 106a, which operates to move and displace the disk in the forward direction indicated by shaded region of vibration axis <NUM>. During the second phase of the vibration cycle, when motion of the contact pad is in the direction indicated by the unshaded region of vibration axis <NUM>, frictional force between contact pad <NUM> and the surface region decreases, from static friction to sliding friction and contact pad <NUM> slips along the contact surface region 106a. As a result, whereas during slippage the contact pad may move disk <NUM> in the rearward direction indicated by the unshaded portion of vibration axis <NUM>, displacement in the rearward direction is less than displacement in the forward direction. The slippage therefore results in a net displacement of disk <NUM> for the vibration cycle in the forward direction.

Attention is directed to <FIG>, which schematically show a robotic hand <NUM>, also known as Accu-Hand, formed of multiple Accu-Fingers <NUM>, and an opposable thumb <NUM>, in accordance with an embodiment of the disclosure. Accu-Fingers <NUM> are, by way of example, in accordance with the Accu-Finger <NUM> shown in <FIG> and <FIG> and described above. Opposable thumb <NUM> may for example, be equipped with a vibrator and operable similarly to Accu-Finger <NUM> as described above. Optionally, opposable thumb <NUM> does not comprise a vibrator and operates only to oppose Accu-Fingers <NUM> to enable Accu-Hand <NUM> to grasp an object.

<FIG>, schematically shows Accu-Hand <NUM> holding a ball <NUM>, between Accu-Fingers <NUM> and opposable thumb <NUM>. The movement of the Accu-Fingers <NUM> and the opposable thumb, with respect to each other are, for example, controlled by a motor (not shown) and controller (not shown) in a palm <NUM>, from which the Accu-Fingers <NUM> and opposable thumb <NUM> extend. Vibrators <NUM> in each of the Accu-fingers <NUM>, as well as that of opposable thumb <NUM> may be operable independently of each other. Additionally, each of Accu-Fingers <NUM> and opposable thumb <NUM> have their respective vibrators <NUM> (<FIG>) rotated to various azimuth angles to generate vibrations along different corresponding vibration axes <NUM>. This allows for various desired movements of ball <NUM>. By way of example, in <FIG> vibration axes <NUM> respectively associated with Accu-Fingers <NUM> and opposable thumb <NUM> are oriented so that vibrations of contact pads of the fingers and thumbs rotate ball <NUM> counterclockwise as indicated by curved arrow <NUM>. This counterclockwise movement occurs as the vibrations from the respective vibrators <NUM> result in displacement of the object <NUM> in the direction of the shaded portions of the vibration axes <NUM>.

While Accu-Fingers <NUM> and <NUM> are shown and described as having three phalanges, an Accu-finger in accordance with an embodiment of the disclosure is not limited to having a plurality of three phalanges. An Accu-Finger may have any number of phalanges and/or mechanical structures for supporting and moving a distal phalange to contact and move an object as desired. The term Accu-Finger may be used to refer only to a distal phalange comprising a vibrator coupled to a contact pad at an extreme end of the phalange for frictionally contacting an object and having a portion of a transmission system for rotating the vibrator.

Vibrator <NUM> schematically shown in <FIG> may include one or more piezo-electric actuators which apply forces along the vibration axis <NUM> and normal to it so as to switch between a sticking phase and a slipping phase and to move the object in a desired direction as detailed above.

In an embodiment, as schematically depicted in <FIG> vibrator <NUM> comprised in distal phalange <NUM> of finger Accu-Finger <NUM> shown in <FIG> includes a rotating mass (ERM) motor <NUM> which operates to switch between a sticking phase and a slipping phase to move an object, such as disk <NUM>, in a desired direction as discussed above. Motor <NUM> optionally has a housing <NUM> comprising an eccentric mass M located at a distance L from an axis and center of rotation R and C respectively of the motor about which ERM motor <NUM> is excited to rotate mass M. For convenience of discussion, features of motor <NUM> are referenced to an XYZ Cartesian coordinate system having a Y-axis coincident with transmission axis <NUM> of distal phalange <NUM>. Features of ERM motor <NUM> are referenced to an xyz coordinate system having a y-axis coincident with the Y-axis and a z-axis coincident with axis of rotation R of ERM motor <NUM>. Features of ERM motor <NUM> are shown enlarged in and inset <NUM>.

Let an angle θ represent angular displacement of rotation axis R from the X-axis, where a counterclockwise angular displacement as seen from a positive z coordinate, is a positive displacement. In <FIG> axis of rotation R is displaced by a negative angle θ. Angular displacement θ is the azimuth angle of vibration axis <NUM> relative to the X-axis of coordinate system <NUM>. If motor <NUM> is excited to rotate mass M about R at an angular velocity ω, (inset <NUM>) mass M exerts a time dependent centrifugal force having x and y components: <MAT> and <MAT>.

Assume that when motor ERM <NUM> is not excited to rotate mass M and the y-axis is perpendicular to gravity, that is when the mass M does not contribute to force with which contact pads <NUM> and <NUM> clamp disc <NUM>, the contact pads clamp disc <NUM> with a clamping force fC. Then, assuming that ŷ is normal to surface contact region 106a then motor M is excited to rotate mass M, contact pad <NUM> exerts a time dependent clamping force FC(t)ŷ in the ŷdirection which is normal to surface contact region 106a of disc <NUM> that may be given by an expression: <MAT> where <MAT> And ERM motor <NUM> exerts a time dependent accelerating force Fa(t)x̂ in the x̂ direction, parallel to surface contact region 106a that may be given by an expression, <MAT> where Γ is a mapping function that accounts for the structural configurations of Accu-Fingers <NUM> and <NUM> and materials from which the Accu-Fingers are made in mapping force MLω<NUM>cosωt to Fa(t)x.

Fa(t) x̂ defines a time dependent force vector FA(t) in coordinate system XYZ having components FA(t)X̂ and FA(t)Ẑ that Accu-Finger <NUM> applies to disc <NUM>. The components may be written, <MAT> <MAT> And if a center of mass, "com", of mass disc <NUM> has a position at time t given by a position vector Pcom(t) with respect to coordinate system XYZ, force FA(t) exerts a time dependent torque τ(t) on disc <NUM> that may be give by an expression, <MAT> where x indicates the cross product.

During a sticking phase FA(t) and clamping force FC(t)ŷ are related by an expression, <MAT> where µS is a coefficient of static friction and equations <NUM>) and <NUM>) are forces that determine linear acceleration of the com of disc <NUM>, and equation <NUM>) is a torque that determines time rate of change in angular momentum of disc <NUM>.

During a slipping phase FA(t) and clamping force FC(t)ŷ are related by an expression, <MAT> Components of forces FA(t) that determine acceleration of the com of disc <NUM> become <MAT> and <MAT> where µk is kinetic friction. Torque that determines time rate of change in angular momentum of disc <NUM> during the slipping phase becomes, <MAT>.

In the description and claims of the present application, each of the verbs, "comprise" "include" and "have", and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of components, elements or parts of the subject or subjects of the verb.

Claim 1:
A robotic finger (<NUM>) comprising:
a vibrator (<NUM>) for vibrating in vibratory motion cycles;
a contact pad (<NUM>) in communication with the vibrator for frictionally contacting an object at a surface contact region (106a) of the object, wherein the vibratory motion of the vibrator generates vibratory motion in the contact pad back and forth along an axis of vibration (<NUM>) and a net displacement of the object along a selected direction along the axis of vibration; and
a transmission system (<NUM>) in communication with the vibrator for rotating the vibrator and the vibration axis to a desired azimuth angle.