WO2020229825A1 - Cable driven robot - Google Patents

Cable driven robot Download PDF

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Publication number
WO2020229825A1
WO2020229825A1 PCT/GB2020/051172 GB2020051172W WO2020229825A1 WO 2020229825 A1 WO2020229825 A1 WO 2020229825A1 GB 2020051172 W GB2020051172 W GB 2020051172W WO 2020229825 A1 WO2020229825 A1 WO 2020229825A1
Authority
WO
WIPO (PCT)
Prior art keywords
optionally
cable
length
effector
cables
Prior art date
Application number
PCT/GB2020/051172
Other languages
French (fr)
Inventor
Patrice Lambert
Christos Bergeles
Lyndon Da Cruz
Original Assignee
King's College London
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by King's College London filed Critical King's College London
Publication of WO2020229825A1 publication Critical patent/WO2020229825A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/003—Programme-controlled manipulators having parallel kinematics
    • B25J9/0078—Programme-controlled manipulators having parallel kinematics actuated by cables
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J13/00—Controls for manipulators
    • B25J13/02—Hand grip control means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J13/00—Controls for manipulators
    • B25J13/02—Hand grip control means
    • B25J13/025—Hand grip control means comprising haptic means
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/016—Input arrangements with force or tactile feedback as computer generated output to the user
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/033—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor
    • G06F3/0346—Pointing devices displaced or positioned by the user, e.g. mice, trackballs, pens or joysticks; Accessories therefor with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors

Definitions

  • the invention relates to a cable driven robot, and a method of using a cable driven robot.
  • the invention relates to a cable driven robot with a grasping platform. More particularly, the invention relates to a device for providing haptic feedback.
  • Haptic devices can be used to provide feedback to a user.
  • a haptic device can be used to allow a user to control a robot, for example in the context of surgery (e.g. retinal surgery).
  • a known type of haptic interface is provided by a parallel robot.
  • Parallel robots comprise multiple serial chains, or legs, connecting a rigid platform to a base in parallel. Only one joint per leg is actuated.
  • Haptic interfaces are actuated interactive devices recording motion and providing force feedback to a human operator.
  • Cable-driven robots are a special type of parallel robots in which flexible cables are used as actuators. One end of each cable is reeled around a rotor twisted by a motor, and the other end is connected to the end-effector. They are generally lighter than rigid links robots and have also been used as haptic devices.
  • parallel robots do not generally provide a grasping capability, which prevents natural interactions. It is sometimes desirable to provide grasping force feedback to allow the operator to feel the shape and stiffness of the manipulated objects.
  • a known approach to provide haptic grasping is to mount an actuated grasper on an existing haptic device. This adds undesirable mass at the worst possible location, i.e. at the furthest point from the base.
  • Bowden cable transmissions may be used as an alternative to provide grasping from base-located motors, but they can produce unwanted friction, stiction, and stiffness at the interaction point.
  • US 2001/0038376 A1 discloses a three-dimensional input apparatus with eight motors, each placed at each comer of a frame.
  • the frame is formed in a cubic lattice and supports one grip with eight strings at the centre.
  • the grip comprises a folding link having a pair of link plates crossed to the other, and a spherical surrounding for containing the folding link linked with a returned spring.
  • the surrounding having elasticity is grasped with the thumb and another finger and the grasping power is increased, the cross angle between the link plates is made smaller. Then, the length of the strings is changed according to the change of the grasping power. Therefore, using the grip, seven degrees of freedom of the grip: the three-dimensional position, the rotation around the arbitrary axes and the grasping is detected, and the corresponding drag is provided to the operator as the tactile sense.
  • a cable driven robot comprising: an end-effector;
  • a cable driven robot comprising:
  • Figure 1 schematically shows a cable driven robot according to an embodiment of the invention:
  • Figure 2 schematically shows an end-effector of a cable driven robot according to an embodiment of the invention.
  • Figure 3 is a schematic of the connection network of the cables of a cable driven robot according to an embodiment of the invention.
  • FIG. 1 schematically shows a cable driven robot 30 according to an embodiment of the invention.
  • the cable driven robot 30 comprises a plurality of actuator cables 1 to 8 and an end-effector 20.
  • the cable driven robot 30 comprises a frame 31, which may be called a base frame.
  • the cable driven robot 30 uses the actuator cables 1 to 8 in tension connecting in parallel the frame 31 to the end-effector 20.
  • the end-effector 20 is a plurality of rigid bodies connected by cables. Each of the actuator cables 1 to 8 has one end connected to the end-effector 20.
  • each actuator cable 1 to 8 is connected to the frame 31.
  • the cable driven robot 30 comprises a plurality of motors.
  • the motors may be mounted on the frame 31.
  • the tension and length of each actuator cable 1 to 8 is controlled by a corresponding motor.
  • the combined action of the motors determines the position/orientation or the forces/moments of the end- effector 20.
  • Figure 2 is a close-up of the end-effector 20.
  • the end- effector 20 comprises a plurality of manual interaction bodies H, Fi, F2.
  • a user of the cable driven robot 30 interacts with the manual interaction bodies H, Fi, F2 using parts of their hand. This is explained in further detail below.
  • the end-effector 20 comprises a plurality of passive cables 9 to 18.
  • the passive cables 9 to 18 connect the manual interaction bodies H, Fi, F2.
  • the passive cables 9 to 18 are kept in tension.
  • the passive cables 9 to 18 in tension provide a one degree of freedom (DOF) grasping capability.
  • DOF degree of freedom
  • two of the manual interaction bodies Fi, F2 can move towards each other or away from each other. This provides the one DOF.
  • This DOF is in addition to the DOFs relating to the position/orientation or the forces/moments of the end-effector 20
  • the passive cables 9 to 18 provide for a lightweight end-effector 20.
  • This means that the cable driven robot 30 is expected to provide all the advantages of known cable driven robots.
  • the cable driven robot 30 can provide grasping capability.
  • each actuator cable 1 to 8 (and in turn the passive cables 9 to 18) is controlled by a corresponding motor on the frame 31.
  • the combined action of the actuator cables 1 to 8 (which is in turn controlled by the action of the motors) determines the one DOF position or force of the two manual interaction bodies Fi, F2 relative to each other.
  • grasping capability is provided without the need for a bearing. This reduces the complexity of manufacturing the cable driven robot 30. This also helps to improve the reliability of the function provided by the cable driven robot 30. It is not necessary to provide maintenance for any bearing.
  • the cable driven robot 30 can provide grasping capability without using any mounted grasping motor. This is possible because of the configurable end-effector 20 comprising passive cables 9 to 18 kept in tension. The operator interacts with the end-effector 20 via, for example, the palm of the hand and the index and thumb fingers. The coordinated action of the actuator cables 1 to 8 fully controls the position and orientation of the end-effector 20 as well as the grasping
  • any type of movement of the end-effector 20 or force control on the end-effector 20 may be effected by a combination of all of the actuator cables 1 to 8 together, so as to keep all of the cables in tension. In some particular motions, some actuator cables 1 to 8 will do most of the work.
  • the actuator cables 5, 6 that are directly connected to the manual interaction bodies Fi, F2 for grasping can be shortened so as to move the manual interaction bodies, Fi, F2 away from each other (or apply a feedback force to the operator in that direction).
  • the actuator cables 5, 6 will pull the most, although other actuator cables may also be shortened or lengthened in order to keep all of the cables in tension.
  • a different combination of actuator cables can be controlled to bring the manual interaction bodies Fi, F2 together (or apply a feedback force to the operator in that direction).
  • the actuator cables 7, 8 connected at points Q7 and Qs may pull the most. If attachment points C5 and C 6 get further apart, then attachment points C3 and C4 need to get closer, and vice versa.
  • the end-effector 20 comprises the passive cables 9 to 18, it is kept lightweight. This improves the realistic nature of the force feedback.
  • the end-effector 20 is lightweight means that the inertia of the end-effector 20 itself does not significantly disturb the rendered forces.
  • the end-effector 20 comprises manual interaction bodies H, Fi, F2, the end-effector 20 remains stiff. This means that the end-effector 20 can mechanically present high frequency content forces to the user.
  • the positions of the manual interaction bodies H, Fi, F2 relative to each other and the tension in the passive cables 9 to 18 correspond to grasping movements of a user manually interacting with the manual interaction bodies H, Fi, F2.
  • the operator can use the palm of their hand, as well as the index and thumb fingers to interact with the cable driven robot 30, including grasping.
  • the end-effector 20 comprises at least three manual interaction bodies H, Fi, F2 for interacting with different parts of a user’s hand.
  • at least one of the manual interaction bodies H is a handle for interacting with a user’s palm.
  • at least one (and preferably two) of the manual interaction bodies Fi, F2 is a ring for interacting with a user’s finger.
  • the user may interact with one of the manual interaction bodies Fi with their index finger and may interact with another of the manual interaction bodies F2 with their thumb.
  • FIG. 3 is a schematic of the connection network of the actuator cables 1 to 8 and the passive cables 9 to 18 of the cable driven robot 30. As shown in Figure 3, optionally there are eight actuator cables 1 to 8. Cable driven robots require at least one more actuator cable than the total number of DOFs. By providing eight actuator cables 1 to 8, the position/orientation of the end-effector 20 can be controlled in six degrees of freedom, with the additional degree of freedom for the grasping capability. The eight actuator cables 1 to 8 can fully control the cable driven robot 30.
  • the length and tension of the actuator cables 1 to 8 correspond to the position/orientation of the end-effector 20 in six degrees of freedom as well as the arrangement of the manual interaction bodies H, Fi, F2.
  • the end-effector 20 comprises at least five attachment points at which at least one of the actuator cables 1 to 8 is attached to the end-effector 20.
  • the examples shown in Figures 2 and 3 comprises six attachment points Ci to C 6.
  • each ring Fi, F2 comprises an attachment point C3, C4 at which an actuator cable 5, 6 is attached to the end-effector 20.
  • the handle H extends between attachment points Ci, C2 at which at least one of the actuator cables 1 to 4 is attached to the end-effector 20. This allows direct control of the manual interaction bodies H, Fi, F2.
  • the handle H extends between attachment points C3, C4 at which a plurality of the passive cables 1 to 4 are attached.
  • Two actuator cables 1, 2 are attached to the end-effector 20 at one attachment point Ci.
  • Two other actuator cables 3, 4 are attached to the end-effector 20 via another attachment point C 2.
  • the attachment points Ci, C 2 are at either end of the handle H. This allows the operator to input accurate control to the end-effector 20 by moving the handle H with the palm of their hand.
  • the arrangement of the end-effector 20 can be considered as an open polyhedron made of six rigid triangular faces, and one open face with the attachment points C3 to C 6 at its vertices.
  • the structure has one DOF, which is used to provide grasping capability between the rings Fi, F2.
  • the handle H is connected to four actuator cables 1 to 4.
  • the four remaining attachment points C3 to C 6 are connected to one actuator cable 5 to 8 each.
  • the whole end-effector 20 can be controlled to move as a rigid body in three translational DOFs and three rotational DOFs.
  • the grasping capability provides a further DOF, meaning that there may be seven DOFs in total.
  • the cable driven robot 30 is controlled using the minimum number of cables.
  • An embodiment of the invention is expected to achieve grasping capability without the use of bearings on the end-effector 20 or any embedded grasper actuators that may require external pneumatic or electric power.
  • the grasping capability is provided by configuring the passive cables 9 to 18 to allow two of the manual interaction bodies Fi, F2to move relative to each other in one DOF.
  • the end-effector 20 comprises at least one attachment body in addition to the manual interaction bodies H, Fi, F2, the attachment body comprising at least one attachment point C 5 , C 6 at which at least one of the actuator cables 7, 8 is attached to the end-effector 20.
  • the end-effector 20 comprises five rigid bodies.
  • the handle H and rings Fi, F2 provide force-feedback to the operator.
  • the upper and bottom attachment points C 5 , C 6 serve to transmit forces between cables.
  • the handle H can be considered as a rigid body with six DOFs while the four remaining bodies are considered as point-objects with three DOFs. Each body is affected not only by the tensions of the actuator cables 1 to 8 and by the operator forces, but also from the tension in the passive cables 9 to 18 of the end-effector 20
  • An embodiment of the invention is expected to achieve all of the advantages of the known cable driven power of robots while additionally offering grasping capability.
  • the invention provides grasping force feedback via multiple contact points to allow the operator to feel the shape and stiffness of a manipulated object. This makes the feedback more natural, i.e. more similar to how the operator would manipulate a tool with their bare hands but with a grasping tool.
  • the invention allows the operator to interact with a remote or virtual environment in a more natural way.
  • the rigid parts of the end-effector 20 can be 3D printed.
  • the cables 1 to 18 can be assembled into the frame 31, without a hardware control or motor installed. This provides a passive assembly. This can be useful for a scientific validation of assumptions of the mathematical model used to design the assembly.
  • the invention can be used in both teleoperation and haptic training involving grasping.
  • the cable driven robot 30 can be used to remotely control a robot equipped with a grasping tool such as scissors, tweezers, forceps or a gripper. Such tools are common in general surgery.
  • the cable driven robot 30 can be used as a human-machine interface in robot-assisted surgery, such as retinal surgery (although it can also be used in other types of surgery).
  • the cable driven robot 30 can be used as a training platform that provides realistic force-feedback. This reduces the cost of training a surgeon to improve their skills.
  • the cable driven robot 30 could alternatively be used in other haptic applications involving grasping such as rehabilitation, video games or teleoperation within remote, dangerous or inaccessible environments.
  • the motor locations are distributed symmetrically on the frame 31.
  • the end-effector 20 is symmetrical.
  • the size of the frame 31 is not particularly limited. Merely as an example, each side of the frame 30 may be at least 500mm and at most 1000mm in length.
  • the axes x, y and z are shown in Figure 1.
  • the x axis may correspond to the axis along which the rings (or cups) Fi, F2 are most separated from each other.
  • the z axis may correspond to the longitudinal direction of the handle H.
  • the y axis is orthogonal to the x axis and the z axis.
  • the frame 30 is longer along the x axis and along the y axis compared to along the z axis.
  • the frame 30 is longer along the x axis compared to along the y axis.
  • the frame 30 may have an equal length along the x axis as along the y axis.
  • the frame 31 may have dimensions of 800 x 700 x 650mm.
  • the frame 31 has dimensions of 800 x 800 x 700mm.
  • the positions of the vertices Qi to Qs may be selected to increase the workspace (volume of effectiveness) of the device.
  • the vertex Qi is at the same position along the x axis as the vertex Q 3 .
  • the vertex Qi is at the same position along the x axis as the vertex Q 5 .
  • the vertex Qi is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis.
  • the vertex Qi is a distance of at most 500mm from the centre point along the x axis.
  • the vertex Qi is a distance of 350mm from the centre point along the x axis.
  • the vertex Qi is at the same position along the y axis as the vertex Q 2 .
  • the vertex Qi is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis.
  • the vertex Qi is a distance of at most 500mm from the centre point along the y axis.
  • the vertex Qi is a distance of 350mm from the centre point along the y axis.
  • the vertex Qi is at the same position along the z axis as the vertex Q 2 .
  • the vertex Qi is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis.
  • the vertex Qi is a distance of at most 500mm from the centre point along the z axis.
  • the vertex Qi is a distance of 320mm from the centre point along the z axis.
  • the vertex Q 2 is at the same position along the x axis as the vertex Q 4 .
  • the vertex Q 2 is at the same position along the x axis as the vertex (3 ⁇ 4.
  • the vertex Q 2 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis.
  • the vertex Q 2 is a distance of at most 500mm from the centre point along the x axis.
  • the vertex Q 2 is a distance of 350mm from the centre point along the x axis.
  • the vertex Q 2 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis.
  • the vertex Q 2 is a distance of at most 500mm from the centre point along the y axis.
  • the vertex Q 2 is a distance of 350mm from the centre point along the y axis.
  • the vertex Q 2 is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis.
  • the vertex Q 2 is a distance of at most 500mm from the centre point along the z axis.
  • the vertex Q 2 is a distance of 320mm from the centre point along the z axis.
  • the vertex Q 3 is at the same position along the x axis as the vertex Q 5 .
  • the vertex Q3 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis.
  • the vertex Q 3 is a distance of at most 500mm from the centre point along the x axis.
  • the vertex Q 3 is a distance of 350mm from the centre point along the x axis.
  • the vertex Q 3 is at the same position along the y axis as the vertex Q 4 .
  • the vertex Q 3 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis.
  • the vertex Q 3 is a distance of at most 500mm from the centre point along the y axis.
  • the vertex Q 3 is a distance of 350mm from the centre point along the y axis.
  • the vertex Q3 is at the same position along the z axis as the vertex Q4.
  • the vertex Q 3 is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis.
  • the vertex Q3 is a distance of at most 500mm from the centre point along the z axis.
  • the vertex Q3 is a distance of 320mm from the centre point along the z axis.
  • the vertex Q 4 is at the same position along the x axis as the vertex (3 ⁇ 4.
  • the vertex Q 4 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis.
  • the vertex Q 4 is a distance of at most 500mm from the centre point along the x axis.
  • the vertex Q 4 is a distance of 350mm from the centre point along the x axis.
  • the vertex Q 4 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis.
  • the vertex Q 4 is a distance of at most 500mm from the centre point along the y axis.
  • the vertex Q 4 is a distance of 350mm from the centre point along the y axis.
  • the vertex Q 4 is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis.
  • the vertex Q 4 is a distance of at most 500mm from the centre point along the z axis.
  • the vertex Q 4 is a distance of 320mm from the centre point along the z axis.
  • the vertex Q 5 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis.
  • the vertex Q 5 is a distance of at most 500mm from the centre point along the x axis.
  • the vertex Q 5 is a distance of 350mm from the centre point along the x axis.
  • the vertex Q 5 is at the same position along the y axis as the vertex (3 ⁇ 4.
  • the vertex Q 5 is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the y axis.
  • the vertex Q 5 is at centre point along the y axis.
  • the vertex Q 5 is at the same position along the z axis as the vertex (3 ⁇ 4.
  • the vertex Q 5 is a distance of at least 10mm, optionally at least 20mm and optionally at least 50mm from the centre point along the z axis.
  • the vertex Q 5 is a distance of at most 100mm from the centre point along the z axis.
  • the vertex Qs is a distance of 60mm from the centre point along the z axis.
  • the vertex Qs is below the centre point along the z axis as viewed in Figure 1.
  • the vertex (3 ⁇ 4 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis.
  • the vertex (3 ⁇ 4 is a distance of at most 500mm from the centre point along the x axis.
  • the vertex (3 ⁇ 4 is a distance of 350mm from the centre point along the x axis.
  • the vertex (3 ⁇ 4 is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the y axis.
  • the vertex (3 ⁇ 4 is at centre point along the y axis.
  • the vertex (3 ⁇ 4 is a distance of at least 10mm, optionally at least 20mm and optionally at least 50mm from the centre point along the z axis.
  • the vertex (3 ⁇ 4 is a distance of at most 100mm from the centre point along the z axis.
  • the vertex (3 ⁇ 4 is a distance of 60mm from the centre point along the z axis.
  • the vertex (3 ⁇ 4 is below the centre point along the z axis as viewed in Figure 1.
  • the vertex Q7 is at the same position along the x axis as the vertex Qx.
  • the vertex Q7 is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the x axis.
  • the vertex Q7 is at the centre point along the x axis.
  • the vertex Q7 is at the same position along the y axis as the vertex Qx.
  • the vertex Q7 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis.
  • the vertex Q7 is a distance of at most 500mm from the centre point along the y axis.
  • the vertex Q7 is a distance of 350mm from the centre point along the y axis.
  • the vertex Q7 is a distance of at least 100mm, and optionally at least 200mm from the centre point along the z axis.
  • the vertex Q7 is a distance of at most 500mm from the centre point along the z axis.
  • the vertex Q7 is a distance of 320mm from the centre point along the z axis.
  • the vertex Qx is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the x axis.
  • the vertex Qx is at the centre point along the x axis.
  • the vertex Qs is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis.
  • the vertex Qs is a distance of at most 500mm from the centre point along the y axis.
  • the vertex Qs is a distance of 350mm from the centre point along the y axis.
  • the vertex Qs is a distance of at least 100mm, and optionally at least 200mm from the centre point along the z axis.
  • the vertex Qs is a distance of at most 500mm from the centre point along the z axis.
  • the vertex Qs is a distance of 320mm from the centre point along the z axis.
  • the size of the handle H is not particularly limited.
  • the handle H is at least 100mm in length.
  • the handle H is at most 150mm in length.
  • the handle H has a length of 120mm. This leaves enough space for the palm of the user’s hand.
  • the length of the passive cables 9 to 18 can be selected so as to constrain the distance between the rings Fi, F2 and the handle H.
  • the distance is not particularly limited.
  • the ring-to-handle distance is at least 50mm.
  • the ring-to-handle distance is at most 100mm.
  • the passive cables 9 to 18 are selected such that the ring-to-handle distance is constrained to be about 70mm.
  • the lengths of the passive cables 9 to 18 may be selected to increase the workspace (volume of effectiveness) of the device.
  • the length of cable 9 is equal to the length of cable 10.
  • the length of cable 9 is less than the length of cable 11.
  • the length of cable 9 is less than the length of cable 12.
  • the length of cable 9 is less than the length of cable 13.
  • the length of cable 9 is less than the length of cable 14.
  • the length of cable 9 is less than the length of cable 15.
  • the length of cable 9 is less than the length of cable 16.
  • the length of cable 9 is less than the length of cable 17.
  • the length of cable 9 is less than the length of cable 18.
  • the length of cable 10 is less than the length of cable 11.
  • the length of cable 10 is less than the length of cable 12.
  • the length of cable 10 is less than the length of cable 13.
  • the length of cable 10 is less than the length of cable 14.
  • the length of cable 10 is less than the length of cable 15.
  • the length of cable 10 is less than the length of cable 16.
  • the length of cable 10 is less than the length of cable 17.
  • the length of cable 10 is less than the length of cable 18.
  • the length of cable 9 is at least 20mm and optionally at least 50mm.
  • the length of cable 9 is at most 200mm and optionally at most 100mm.
  • the length of cable 9 is 54mm.
  • the length of cable 10 is at least 20mm and optionally at least 50mm.
  • the length of cable 10 is at most 200mm and optionally at most 100mm.
  • the length of cable 10 is 54mm.
  • the length of cable 11 is equal to the length of cable 12.
  • the length of cable 11 is less than the length of cable 13.
  • the length of cable 11 is less than the length of cable 14.
  • the length of cable 11 is less than the length of cable 15.
  • the length of cable 11 is less than the length of cable 16.
  • the length of cable 11 is less than the length of cable 17.
  • the length of cable 11 is less than the length of cable 18.
  • the length of cable 12 is less than the length of cable 13.
  • the length of cable 12 is less than the length of cable 14.
  • the length of cable 12 is less than the length of cable 15.
  • the length of cable 12 is less than the length of cable 16.
  • the length of cable 12 is less than the length of cable 17.
  • the length of cable 12 is less than the length of cable 18.
  • the length of cable 11 is at least 20mm and optionally at least 50mm.
  • the length of cable 11 is at most 200mm and optionally at most 100mm.
  • the length of cable 11 is 69mm.
  • the length of cable 12 is at least 20mm and optionally at least 50mm.
  • the length of cable 12 is at most 200mm and optionally at most 100mm.
  • the length of cable 12 is 69mm.
  • the length of cable 13 is less than the length of cable 14.
  • the length of cable 13 is less than the length of cable 15.
  • the length of cable 13 is greater than the length of cable 16.
  • the length of cable 13 is less than the length of cable 17.
  • the length of cable 13 is less than the length of cable 18.
  • the length of cable 13 is at least 50mm and optionally at least 100mm.
  • the length of cable 13 is at most 200mm.
  • the length of cable 13 is 108mm.
  • the length of cable 14 is equal to the length of cable 15.
  • the length of cable 14 is greater than the length of cable 16.
  • the length of cable 14 is less than the length of cable 17.
  • the length of cable 14 is less than the length of cable 18.
  • the length of cable 15 is greater than the length of cable 16.
  • the length of cable 15 is less than the length of cable 17.
  • the length of cable 15 is less than the length of cable 18.
  • the length of cable 14 is at least 50mm and optionally at least 100mm.
  • the length of cable 14 is at most 200mm.
  • the length of cable 14 is 145mm.
  • the length of cable 15 is at least 50mm and optionally at least 100mm.
  • the length of cable 15 is at most 200mm.
  • the length of cable 15 is 145mm.
  • the length of cable 16 is less than the length of cable 17.
  • the length of cable 16 is less than the length of cable 18.
  • the length of cable 16 is at least 20mm and optionally at least 50mm.
  • the length of cable 16 is at most 200mm and optionally at most 100mm.
  • the length of cable 16 is 91mm.
  • the length of cable 17 is equal to the length of cable 18.
  • the length of cable 17 is at least 50mm and optionally at least 100mm.
  • the length of cable 17 is at most 200mm.
  • the length of cable 17 is 148mm.
  • the length of cable 18 is at least 50mm and optionally at least 100mm.
  • the length of cable 18 is at most 200mm.
  • the length of cable 18 is 148mm.
  • the actuator cables 1 to 8 of the cable driven robot 30 are controlled such that all of the cables 1 to 18 are kept in tension.
  • the tension in each cable 1 to 18 is kept to be a minimum of 0.5N.
  • the tension in each cable 1 to 18 is at most 50N. This prevents sagging of the cables 1 to 18.
  • the frame 31 is formed as a cubic lattice.
  • some of the actuator cables 1 to 4 are connected to vertices Qi to Q4 of the frame 31.
  • the cables 1 to 4 that are connected to the handle H may be connected to the vertices Qi to Q4 of the frame 31.
  • actuator cables 5 to 8 may be connected to the centre point of edges of the frame 31.
  • actuator cables 5, 6 are connected between the rings Fi, F2 and centre points Q5, Qe of edges of the frame 31.
  • Further actuator cables 7, 8 are connected between the attachment bodies at attachment points C5, C 6 to the centre point Q7, Qx of edges of the frame 31.
  • the positions of the frame 31 at which the actuator cables 1 to 8 are attached may be selected so as to optimise the kinematics of the design.
  • each ring Fi, F2 comprises at least one attachment point C3, C4 at which a plurality of the passive cables 9 to 12, 14, 15, 17, 18 are attached.
  • a plurality of the passive cables 9 to 13, 16 are attached to the attachment points C5, C 6 of the attachment bodies that are in addition to the manual interaction bodies H, Fi, F2. It will be understood that the invention is not limited to the embodiments above- described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub combinations of one or more features described herein.

Abstract

A cable driven robot (30) comprises an end-effector (20) and a plurality of actuator cables (1 - 8), each having one end connected to the end-effector (20). The end-effector comprises a plurality of manual interaction bodies (H,F1, F2), and a plurality of passive cables (9 - 18) connecting the manual interaction bodies (H, F1, F2).

Description

CABLE DRIVEN ROBOT
The invention relates to a cable driven robot, and a method of using a cable driven robot. In an embodiment, the invention relates to a cable driven robot with a grasping platform. More particularly, the invention relates to a device for providing haptic feedback.
Background
Haptic devices can be used to provide feedback to a user. For example, such a haptic device can be used to allow a user to control a robot, for example in the context of surgery (e.g. retinal surgery). A known type of haptic interface is provided by a parallel robot.
Parallel robots comprise multiple serial chains, or legs, connecting a rigid platform to a base in parallel. Only one joint per leg is actuated. Haptic interfaces are actuated interactive devices recording motion and providing force feedback to a human operator.
Cable-driven robots are a special type of parallel robots in which flexible cables are used as actuators. One end of each cable is reeled around a rotor twisted by a motor, and the other end is connected to the end-effector. They are generally lighter than rigid links robots and have also been used as haptic devices.
Despite their advantages, parallel robots do not generally provide a grasping capability, which prevents natural interactions. It is sometimes desirable to provide grasping force feedback to allow the operator to feel the shape and stiffness of the manipulated objects. A known approach to provide haptic grasping is to mount an actuated grasper on an existing haptic device. This adds undesirable mass at the worst possible location, i.e. at the furthest point from the base. Bowden cable transmissions may be used as an alternative to provide grasping from base-located motors, but they can produce unwanted friction, stiction, and stiffness at the interaction point.
US 2001/0038376 A1 discloses a three-dimensional input apparatus with eight motors, each placed at each comer of a frame. The frame is formed in a cubic lattice and supports one grip with eight strings at the centre. The grip comprises a folding link having a pair of link plates crossed to the other, and a spherical surrounding for containing the folding link linked with a returned spring. When the surrounding having elasticity is grasped with the thumb and another finger and the grasping power is increased, the cross angle between the link plates is made smaller. Then, the length of the strings is changed according to the change of the grasping power. Therefore, using the grip, seven degrees of freedom of the grip: the three-dimensional position, the rotation around the arbitrary axes and the grasping is detected, and the corresponding drag is provided to the operator as the tactile sense.
However, the manufacture of the gripper is complicated, requiring a bearing. Furthermore, there is limited control over the feedback force provided to the operator as a result of using the returned spring.
It is an aim of the present disclosure to provide a cable driven robot with a grasping function, which has a simpler construction and/or which can provide more controlled feedback to a user.
Brief Summary
According to a first aspect there is provided a cable driven robot comprising: an end-effector; and
a plurality of actuator cables, each having one end connected to the end- effector, wherein the end-effector comprises:
a plurality of manual interaction bodies; and a plurality of passive cables connecting the manual interaction bodies.
According to a second aspect there is provided a method of using a cable driven robot, the cable driven robot comprising:
an end-effector; and
a plurality of actuator cables, each having one end connected to the end- effector, wherein the end-effector comprises:
a plurality of manual interaction bodies; and
a plurality of passive cables connecting the manual interaction bodies.
Brief Description of the Drawings
Embodiments will now be described by way of example only, with reference to the Figures, in which:
Figure 1 schematically shows a cable driven robot according to an embodiment of the invention:
Figure 2 schematically shows an end-effector of a cable driven robot according to an embodiment of the invention: and
Figure 3 is a schematic of the connection network of the cables of a cable driven robot according to an embodiment of the invention.
Detailed Description
Figure 1 schematically shows a cable driven robot 30 according to an embodiment of the invention. As shown in Figure 1, the cable driven robot 30 comprises a plurality of actuator cables 1 to 8 and an end-effector 20. Additionally, the cable driven robot 30 comprises a frame 31, which may be called a base frame. The cable driven robot 30 uses the actuator cables 1 to 8 in tension connecting in parallel the frame 31 to the end-effector 20. The end-effector 20 is a plurality of rigid bodies connected by cables. Each of the actuator cables 1 to 8 has one end connected to the end-effector 20.
The other end of each actuator cable 1 to 8 is connected to the frame 31. Although not shown in Figure 1, the cable driven robot 30 comprises a plurality of motors. The motors may be mounted on the frame 31. The tension and length of each actuator cable 1 to 8 is controlled by a corresponding motor. The combined action of the motors determines the position/orientation or the forces/moments of the end- effector 20.
Figure 2 is a close-up of the end-effector 20. As shown in Figure 2, the end- effector 20 comprises a plurality of manual interaction bodies H, Fi, F2. A user of the cable driven robot 30 interacts with the manual interaction bodies H, Fi, F2 using parts of their hand. This is explained in further detail below.
As shown in Figure 2, the end-effector 20 comprises a plurality of passive cables 9 to 18. The passive cables 9 to 18 connect the manual interaction bodies H, Fi, F2. In use, the passive cables 9 to 18 are kept in tension. The passive cables 9 to 18 in tension provide a one degree of freedom (DOF) grasping capability. In particular, two of the manual interaction bodies Fi, F2 can move towards each other or away from each other. This provides the one DOF. This DOF is in addition to the DOFs relating to the position/orientation or the forces/moments of the end-effector 20
The passive cables 9 to 18 provide for a lightweight end-effector 20. This means that the cable driven robot 30 is expected to provide all the advantages of known cable driven robots. In addition, the cable driven robot 30 can provide grasping capability.
The tension and length of each actuator cable 1 to 8 (and in turn the passive cables 9 to 18) is controlled by a corresponding motor on the frame 31. The combined action of the actuator cables 1 to 8 (which is in turn controlled by the action of the motors) determines the one DOF position or force of the two manual interaction bodies Fi, F2 relative to each other.
By providing the manual interaction bodies H, Fi, F2 connected by the passive cables 9 to 18, grasping capability is provided without the need for a bearing. This reduces the complexity of manufacturing the cable driven robot 30. This also helps to improve the reliability of the function provided by the cable driven robot 30. It is not necessary to provide maintenance for any bearing.
The cable driven robot 30 can provide grasping capability without using any mounted grasping motor. This is possible because of the configurable end-effector 20 comprising passive cables 9 to 18 kept in tension. The operator interacts with the end-effector 20 via, for example, the palm of the hand and the index and thumb fingers. The coordinated action of the actuator cables 1 to 8 fully controls the position and orientation of the end-effector 20 as well as the grasping
configuration while keeping all the passive cables 9 to 18 in tension.
In general, any type of movement of the end-effector 20 or force control on the end-effector 20 may be effected by a combination of all of the actuator cables 1 to 8 together, so as to keep all of the cables in tension. In some particular motions, some actuator cables 1 to 8 will do most of the work.
For example, the actuator cables 5, 6 that are directly connected to the manual interaction bodies Fi, F2 for grasping can be shortened so as to move the manual interaction bodies, Fi, F2 away from each other (or apply a feedback force to the operator in that direction). The actuator cables 5, 6 will pull the most, although other actuator cables may also be shortened or lengthened in order to keep all of the cables in tension. A different combination of actuator cables can be controlled to bring the manual interaction bodies Fi, F2 together (or apply a feedback force to the operator in that direction). In order to close the grasper between interaction bodies Fi and F2, then the actuator cables 7, 8 connected at points Q7 and Qs (see Figure 1) may pull the most. If attachment points C5 and C6 get further apart, then attachment points C3 and C4 need to get closer, and vice versa.
By providing that the end-effector 20 comprises the passive cables 9 to 18, it is kept lightweight. This improves the realistic nature of the force feedback. In particular, by providing that the end-effector 20 is lightweight means that the inertia of the end-effector 20 itself does not significantly disturb the rendered forces. Meanwhile, by providing that the end-effector 20 comprises manual interaction bodies H, Fi, F2, the end-effector 20 remains stiff. This means that the end-effector 20 can mechanically present high frequency content forces to the user.
The positions of the manual interaction bodies H, Fi, F2 relative to each other and the tension in the passive cables 9 to 18 correspond to grasping movements of a user manually interacting with the manual interaction bodies H, Fi, F2. For example, the operator can use the palm of their hand, as well as the index and thumb fingers to interact with the cable driven robot 30, including grasping. As shown in Figure 2, optionally the end-effector 20 comprises at least three manual interaction bodies H, Fi, F2 for interacting with different parts of a user’s hand. Optionally, at least one of the manual interaction bodies H is a handle for interacting with a user’s palm. Optionally, at least one (and preferably two) of the manual interaction bodies Fi, F2 is a ring for interacting with a user’s finger. For example, the user may interact with one of the manual interaction bodies Fi with their index finger and may interact with another of the manual interaction bodies F2 with their thumb.
The operator interacts with the end-effector 20 using the palm of their hand on body H, and the index and thumb fingers on the bodies Fi, F2. The bodies H, Fi, F2 are connected by the network of passive cables 9 to 18 kept in tension by the independently controlled parallel actuator cables 1 to 8. Figure 3 is a schematic of the connection network of the actuator cables 1 to 8 and the passive cables 9 to 18 of the cable driven robot 30. As shown in Figure 3, optionally there are eight actuator cables 1 to 8. Cable driven robots require at least one more actuator cable than the total number of DOFs. By providing eight actuator cables 1 to 8, the position/orientation of the end-effector 20 can be controlled in six degrees of freedom, with the additional degree of freedom for the grasping capability. The eight actuator cables 1 to 8 can fully control the cable driven robot 30.
Hence, optionally the length and tension of the actuator cables 1 to 8 correspond to the position/orientation of the end-effector 20 in six degrees of freedom as well as the arrangement of the manual interaction bodies H, Fi, F2.
Optionally, as shown in Figures 2 and 3, the end-effector 20 comprises at least five attachment points at which at least one of the actuator cables 1 to 8 is attached to the end-effector 20. In particular, the examples shown in Figures 2 and 3 comprises six attachment points Ci to C6.
By providing more than four attachment points, the manual interaction bodies H, Fi, F2 of the end-effector 20 can be controlled more carefully and accurately compared to if there are fewer attachment points. For example, US 2001/0038376 A1 discloses only four attachment points to the gripper, thereby providing less control over the gripper compared to in the present invention.
As shown in Figures 2 and 3, optionally each ring Fi, F2 comprises an attachment point C3, C4 at which an actuator cable 5, 6 is attached to the end-effector 20. As shown in Figures 2 and 3, optionally the handle H extends between attachment points Ci, C2 at which at least one of the actuator cables 1 to 4 is attached to the end-effector 20. This allows direct control of the manual interaction bodies H, Fi, F2. As shown in Figure 3, optionally the handle H extends between attachment points C3, C4 at which a plurality of the passive cables 1 to 4 are attached. Two actuator cables 1, 2 are attached to the end-effector 20 at one attachment point Ci. Two other actuator cables 3, 4 are attached to the end-effector 20 via another attachment point C2. The attachment points Ci, C2 are at either end of the handle H. This allows the operator to input accurate control to the end-effector 20 by moving the handle H with the palm of their hand.
As explained above, all of the passive cables 9 to 18 are kept in tension. As shown in Figure 3, the arrangement of the end-effector 20 can be considered as an open polyhedron made of six rigid triangular faces, and one open face with the attachment points C3 to C6 at its vertices. The structure has one DOF, which is used to provide grasping capability between the rings Fi, F2. The handle H is connected to four actuator cables 1 to 4. The four remaining attachment points C3 to C6 are connected to one actuator cable 5 to 8 each.
The whole end-effector 20 can be controlled to move as a rigid body in three translational DOFs and three rotational DOFs. The grasping capability provides a further DOF, meaning that there may be seven DOFs in total. By providing eight actuator cables 1 to 8, the cable driven robot 30 is controlled using the minimum number of cables. An embodiment of the invention is expected to achieve grasping capability without the use of bearings on the end-effector 20 or any embedded grasper actuators that may require external pneumatic or electric power. The grasping capability is provided by configuring the passive cables 9 to 18 to allow two of the manual interaction bodies Fi, F2to move relative to each other in one DOF.
Optionally, the end-effector 20 comprises at least one attachment body in addition to the manual interaction bodies H, Fi, F2, the attachment body comprising at least one attachment point C5, C6 at which at least one of the actuator cables 7, 8 is attached to the end-effector 20. In particular, as shown in Figure 3, optionally the end-effector 20 comprises five rigid bodies. The handle H and rings Fi, F2 provide force-feedback to the operator. In addition, the upper and bottom attachment points C5, C6 serve to transmit forces between cables. The handle H can be considered as a rigid body with six DOFs while the four remaining bodies are considered as point-objects with three DOFs. Each body is affected not only by the tensions of the actuator cables 1 to 8 and by the operator forces, but also from the tension in the passive cables 9 to 18 of the end-effector 20
An embodiment of the invention is expected to achieve all of the advantages of the known cable driven power of robots while additionally offering grasping capability. The invention provides grasping force feedback via multiple contact points to allow the operator to feel the shape and stiffness of a manipulated object. This makes the feedback more natural, i.e. more similar to how the operator would manipulate a tool with their bare hands but with a grasping tool. The invention allows the operator to interact with a remote or virtual environment in a more natural way.
Optionally, the rigid parts of the end-effector 20 can be 3D printed. The cables 1 to 18 can be assembled into the frame 31, without a hardware control or motor installed. This provides a passive assembly. This can be useful for a scientific validation of assumptions of the mathematical model used to design the assembly.
The invention can be used in both teleoperation and haptic training involving grasping. In teleoperation, the cable driven robot 30 can be used to remotely control a robot equipped with a grasping tool such as scissors, tweezers, forceps or a gripper. Such tools are common in general surgery. The cable driven robot 30 can be used as a human-machine interface in robot-assisted surgery, such as retinal surgery (although it can also be used in other types of surgery).
The cable driven robot 30 can be used as a training platform that provides realistic force-feedback. This reduces the cost of training a surgeon to improve their skills. The cable driven robot 30 could alternatively be used in other haptic applications involving grasping such as rehabilitation, video games or teleoperation within remote, dangerous or inaccessible environments.
Optionally, the motor locations are distributed symmetrically on the frame 31. Optionally, the end-effector 20 is symmetrical.
The size of the frame 31 is not particularly limited. Merely as an example, each side of the frame 30 may be at least 500mm and at most 1000mm in length. The axes x, y and z are shown in Figure 1. The x axis may correspond to the axis along which the rings (or cups) Fi, F2 are most separated from each other. The z axis may correspond to the longitudinal direction of the handle H. The y axis is orthogonal to the x axis and the z axis. Optionally, the frame 30 is longer along the x axis and along the y axis compared to along the z axis. Optionally, the frame 30 is longer along the x axis compared to along the y axis. Alternatively, the frame 30 may have an equal length along the x axis as along the y axis. Merely as a specific example, the frame 31 may have dimensions of 800 x 700 x 650mm. In another example, the frame 31 has dimensions of 800 x 800 x 700mm.
The positions of the vertices Qi to Qs may be selected to increase the workspace (volume of effectiveness) of the device.
Optionally, the vertex Qi is at the same position along the x axis as the vertex Q3. Optionally, the vertex Qi is at the same position along the x axis as the vertex Q5. Optionally, the vertex Qi is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis. Optionally, the vertex Qi is a distance of at most 500mm from the centre point along the x axis. Optionally, the vertex Qi is a distance of 350mm from the centre point along the x axis.
Optionally, the vertex Qi is at the same position along the y axis as the vertex Q2. Optionally, the vertex Qi is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis. Optionally, the vertex Qi is a distance of at most 500mm from the centre point along the y axis. Optionally, the vertex Qi is a distance of 350mm from the centre point along the y axis.
Optionally, the vertex Qi is at the same position along the z axis as the vertex Q2. Optionally, the vertex Qi is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis. Optionally, the vertex Qi is a distance of at most 500mm from the centre point along the z axis. Optionally, the vertex Qi is a distance of 320mm from the centre point along the z axis.
Optionally, the vertex Q2 is at the same position along the x axis as the vertex Q4. Optionally, the vertex Q2 is at the same position along the x axis as the vertex (¾. Optionally, the vertex Q2 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis. Optionally, the vertex Q2 is a distance of at most 500mm from the centre point along the x axis. Optionally, the vertex Q2 is a distance of 350mm from the centre point along the x axis.
Optionally, the vertex Q2 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis. Optionally, the vertex Q2 is a distance of at most 500mm from the centre point along the y axis. Optionally, the vertex Q2 is a distance of 350mm from the centre point along the y axis.
Optionally, the vertex Q2 is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis. Optionally, the vertex Q2 is a distance of at most 500mm from the centre point along the z axis. Optionally, the vertex Q2 is a distance of 320mm from the centre point along the z axis.
Optionally, the vertex Q3 is at the same position along the x axis as the vertex Q5. Optionally, the vertex Q3 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis. Optionally, the vertex Q3 is a distance of at most 500mm from the centre point along the x axis. Optionally, the vertex Q3 is a distance of 350mm from the centre point along the x axis.
Optionally, the vertex Q3 is at the same position along the y axis as the vertex Q4. Optionally, the vertex Q3 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis. Optionally, the vertex Q3 is a distance of at most 500mm from the centre point along the y axis. Optionally, the vertex Q3 is a distance of 350mm from the centre point along the y axis. Optionally, the vertex Q3 is at the same position along the z axis as the vertex Q4. Optionally, the vertex Q3 is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis. Optionally, the vertex Q3 is a distance of at most 500mm from the centre point along the z axis. Optionally, the vertex Q3 is a distance of 320mm from the centre point along the z axis.
Optionally, the vertex Q4 is at the same position along the x axis as the vertex (¾. Optionally, the vertex Q4 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis. Optionally, the vertex Q4 is a distance of at most 500mm from the centre point along the x axis. Optionally, the vertex Q4 is a distance of 350mm from the centre point along the x axis.
Optionally, the vertex Q4 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis. Optionally, the vertex Q4 is a distance of at most 500mm from the centre point along the y axis. Optionally, the vertex Q4 is a distance of 350mm from the centre point along the y axis.
Optionally, the vertex Q4 is a distance of at least 100mm and optionally at least 200mm from the centre point along the z axis. Optionally, the vertex Q4 is a distance of at most 500mm from the centre point along the z axis. Optionally, the vertex Q4 is a distance of 320mm from the centre point along the z axis.
Optionally, the vertex Q5 is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis. Optionally, the vertex Q5 is a distance of at most 500mm from the centre point along the x axis. Optionally, the vertex Q5 is a distance of 350mm from the centre point along the x axis.
Optionally, the vertex Q5 is at the same position along the y axis as the vertex (¾. Optionally, the vertex Q5 is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the y axis. Optionally, the vertex Q5 is at centre point along the y axis. Optionally, the vertex Q5 is at the same position along the z axis as the vertex (¾. Optionally, the vertex Q5 is a distance of at least 10mm, optionally at least 20mm and optionally at least 50mm from the centre point along the z axis. Optionally, the vertex Q5 is a distance of at most 100mm from the centre point along the z axis. Optionally, the vertex Qs is a distance of 60mm from the centre point along the z axis. Optionally, the vertex Qs is below the centre point along the z axis as viewed in Figure 1.
Optionally, the vertex (¾ is a distance of at least 100mm and optionally at least 200mm from the centre point along the x axis. Optionally, the vertex (¾ is a distance of at most 500mm from the centre point along the x axis. Optionally, the vertex (¾ is a distance of 350mm from the centre point along the x axis.
Optionally, the vertex (¾ is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the y axis. Optionally, the vertex (¾ is at centre point along the y axis. Optionally, the vertex (¾ is a distance of at least 10mm, optionally at least 20mm and optionally at least 50mm from the centre point along the z axis. Optionally, the vertex (¾ is a distance of at most 100mm from the centre point along the z axis. Optionally, the vertex (¾ is a distance of 60mm from the centre point along the z axis. Optionally, the vertex (¾ is below the centre point along the z axis as viewed in Figure 1.
Optionally, the vertex Q7 is at the same position along the x axis as the vertex Qx. Optionally, the vertex Q7 is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the x axis. Optionally, the vertex Q7 is at the centre point along the x axis. Optionally, the vertex Q7 is at the same position along the y axis as the vertex Qx. Optionally, the vertex Q7 is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis. Optionally, the vertex Q7 is a distance of at most 500mm from the centre point along the y axis. Optionally, the vertex Q7 is a distance of 350mm from the centre point along the y axis.
Optionally, the vertex Q7 is a distance of at least 100mm, and optionally at least 200mm from the centre point along the z axis. Optionally, the vertex Q7 is a distance of at most 500mm from the centre point along the z axis. Optionally, the vertex Q7 is a distance of 320mm from the centre point along the z axis. Optionally, the vertex Qx is a distance of at most 100mm, optionally at most 50mm, optionally at most 20mm and optionally at most 10mm from the centre point along the x axis. Optionally, the vertex Qx is at the centre point along the x axis. Optionally, the vertex Qs is a distance of at least 100mm and optionally at least 200mm from the centre point along the y axis. Optionally, the vertex Qs is a distance of at most 500mm from the centre point along the y axis. Optionally, the vertex Qs is a distance of 350mm from the centre point along the y axis.
Optionally, the vertex Qs is a distance of at least 100mm, and optionally at least 200mm from the centre point along the z axis. Optionally, the vertex Qs is a distance of at most 500mm from the centre point along the z axis. Optionally, the vertex Qs is a distance of 320mm from the centre point along the z axis.
The size of the handle H is not particularly limited. For example, optionally the handle H is at least 100mm in length. Optionally, the handle H is at most 150mm in length. In one example, the handle H has a length of 120mm. This leaves enough space for the palm of the user’s hand.
The length of the passive cables 9 to 18 can be selected so as to constrain the distance between the rings Fi, F2 and the handle H. The distance is not particularly limited. As an example, the ring-to-handle distance is at least 50mm. Optionally, the ring-to-handle distance is at most 100mm. In one example, the passive cables 9 to 18 are selected such that the ring-to-handle distance is constrained to be about 70mm.
The lengths of the passive cables 9 to 18 may be selected to increase the workspace (volume of effectiveness) of the device.
Optionally, the length of cable 9 is equal to the length of cable 10. Optionally, the length of cable 9 is less than the length of cable 11. Optionally, the length of cable 9 is less than the length of cable 12. Optionally, the length of cable 9 is less than the length of cable 13. Optionally, the length of cable 9 is less than the length of cable 14. Optionally, the length of cable 9 is less than the length of cable 15. Optionally, the length of cable 9 is less than the length of cable 16. Optionally, the length of cable 9 is less than the length of cable 17. Optionally, the length of cable 9 is less than the length of cable 18. Optionally, the length of cable 10 is less than the length of cable 11. Optionally, the length of cable 10 is less than the length of cable 12. Optionally, the length of cable 10 is less than the length of cable 13. Optionally, the length of cable 10 is less than the length of cable 14. Optionally, the length of cable 10 is less than the length of cable 15. Optionally, the length of cable 10 is less than the length of cable 16. Optionally, the length of cable 10 is less than the length of cable 17. Optionally, the length of cable 10 is less than the length of cable 18. Optionally, the length of cable 9 is at least 20mm and optionally at least 50mm. Optionally, the length of cable 9 is at most 200mm and optionally at most 100mm. Optionally, the length of cable 9 is 54mm. Optionally, the length of cable 10 is at least 20mm and optionally at least 50mm. Optionally, the length of cable 10 is at most 200mm and optionally at most 100mm.
Optionally, the length of cable 10 is 54mm.
Optionally, the length of cable 11 is equal to the length of cable 12. Optionally, the length of cable 11 is less than the length of cable 13. Optionally, the length of cable 11 is less than the length of cable 14. Optionally, the length of cable 11 is less than the length of cable 15. Optionally, the length of cable 11 is less than the length of cable 16. Optionally, the length of cable 11 is less than the length of cable 17. Optionally, the length of cable 11 is less than the length of cable 18. Optionally, the length of cable 12 is less than the length of cable 13. Optionally, the length of cable 12 is less than the length of cable 14. Optionally, the length of cable 12 is less than the length of cable 15. Optionally, the length of cable 12 is less than the length of cable 16. Optionally, the length of cable 12 is less than the length of cable 17. Optionally, the length of cable 12 is less than the length of cable 18. Optionally, the length of cable 11 is at least 20mm and optionally at least 50mm. Optionally, the length of cable 11 is at most 200mm and optionally at most 100mm. Optionally, the length of cable 11 is 69mm. Optionally, the length of cable 12 is at least 20mm and optionally at least 50mm. Optionally, the length of cable 12 is at most 200mm and optionally at most 100mm. Optionally, the length of cable 12 is 69mm.
Optionally, the length of cable 13 is less than the length of cable 14. Optionally, the length of cable 13 is less than the length of cable 15. Optionally, the length of cable 13 is greater than the length of cable 16. Optionally, the length of cable 13 is less than the length of cable 17. Optionally, the length of cable 13 is less than the length of cable 18. Optionally, the length of cable 13 is at least 50mm and optionally at least 100mm. Optionally, the length of cable 13 is at most 200mm. Optionally, the length of cable 13 is 108mm.
Optionally, the length of cable 14 is equal to the length of cable 15. Optionally, the length of cable 14 is greater than the length of cable 16. Optionally, the length of cable 14 is less than the length of cable 17. Optionally, the length of cable 14 is less than the length of cable 18. Optionally, the length of cable 15 is greater than the length of cable 16. Optionally, the length of cable 15 is less than the length of cable 17. Optionally, the length of cable 15 is less than the length of cable 18. Optionally, the length of cable 14 is at least 50mm and optionally at least 100mm. Optionally, the length of cable 14 is at most 200mm. Optionally, the length of cable 14 is 145mm. Optionally, the length of cable 15 is at least 50mm and optionally at least 100mm. Optionally, the length of cable 15 is at most 200mm. Optionally, the length of cable 15 is 145mm.
Optionally, the length of cable 16 is less than the length of cable 17. Optionally, the length of cable 16 is less than the length of cable 18. Optionally, the length of cable 16 is at least 20mm and optionally at least 50mm. Optionally, the length of cable 16 is at most 200mm and optionally at most 100mm. Optionally, the length of cable 16 is 91mm.
Optionally, the length of cable 17 is equal to the length of cable 18. Optionally, the length of cable 17 is at least 50mm and optionally at least 100mm. Optionally, the length of cable 17 is at most 200mm. Optionally, the length of cable 17 is 148mm. Optionally, the length of cable 18 is at least 50mm and optionally at least 100mm. Optionally, the length of cable 18 is at most 200mm. Optionally, the length of cable 18 is 148mm.
As explained above, the actuator cables 1 to 8 of the cable driven robot 30 are controlled such that all of the cables 1 to 18 are kept in tension. Optionally, the tension in each cable 1 to 18 is kept to be a minimum of 0.5N. Optionally, the tension in each cable 1 to 18 is at most 50N. This prevents sagging of the cables 1 to 18.
As shown in Figure 1, optionally the frame 31 is formed as a cubic lattice. As shown in Figure 1, optionally some of the actuator cables 1 to 4 are connected to vertices Qi to Q4 of the frame 31. In particular, the cables 1 to 4 that are connected to the handle H may be connected to the vertices Qi to Q4 of the frame 31.
Meanwhile, other actuator cables 5 to 8 may be connected to the centre point of edges of the frame 31. For example, actuator cables 5, 6 are connected between the rings Fi, F2 and centre points Q5, Qe of edges of the frame 31. Further actuator cables 7, 8 are connected between the attachment bodies at attachment points C5, C6 to the centre point Q7, Qx of edges of the frame 31.
The positions of the frame 31 at which the actuator cables 1 to 8 are attached may be selected so as to optimise the kinematics of the design.
As shown in Figure 2, the handle extends between attachment points Ci, C2 at which a plurality of the passive cables 13 to 18 are attached. Meanwhile, each ring Fi, F2 comprises at least one attachment point C3, C4 at which a plurality of the passive cables 9 to 12, 14, 15, 17, 18 are attached.
A plurality of the passive cables 9 to 13, 16 are attached to the attachment points C5, C6 of the attachment bodies that are in addition to the manual interaction bodies H, Fi, F2. It will be understood that the invention is not limited to the embodiments above- described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub combinations of one or more features described herein.

Claims

Claims
1. A cable driven robot comprising:
an end-effector; and
a plurality of actuator cables, each having one end connected to the end-effector, wherein the end-effector comprises:
a plurality of manual interaction bodies; and
a plurality of passive cables connecting the manual interaction bodies.
2. The cable driven robot of claim 1, wherein the positions of the manual interaction bodies relative to each other and the tension in the passive cables correspond to grasping movements of a user manually interacting with the manual interaction bodies.
3. The cable driven robot of any preceding claim, wherein the length and tension of the actuator cables correspond to the position/orientation of the end-effector in six degrees of freedom and the arrangement of the manual interaction bodies.
4. The cable driven robot of any preceding claim, wherein the end-effector comprises at least five attachment points at which at least one of the actuator cables is attached to the end-effector.
5. The cable driven robot of any preceding claim, wherein the end-effector comprises at least five attachment points at which a plurality of the passive cables are attached.
6. The cable driven robot of any preceding claim, wherein the passive cables are configured to allow two of the manual interaction bodies to move relative to each other in at least one degree of freedom.
7. The cable driven robot of any preceding claim, wherein the end-effector comprises at least three manual interaction bodies for interacting with different parts of a user’s hand.
8. The cable driven robot of any preceding claim, wherein at least one of the manual interaction bodies is a handle for interacting with a user’s palm.
9. The cable driven robot of claim 8, wherein the handle extends between attachment points at which at least one of the actuator cables is attached to the end-effector.
10. The cable driven robot of claim 8 or 9, wherein the handle extends between attachment points at which a plurality of the passive cables are attached.
11. The cable driven robot of any preceding claim, wherein at least one of the manual interaction bodies is a ring for interacting with a user’s finger.
12. The cable driven robot of claim 11, wherein at least two of the manual interaction bodies are ring for interacting with a user’s finger.
13. The cable driven robot of claim 11 or 12, wherein each ring comprises at least one attachment point at which at least one of the actuator cables is attached to the end-effector.
14. The cable driven robot of any of claims 11 to 13, wherein each ring
comprises at least one attachment point at which a plurality of the passive cables are attached.
15. The cable driven robot of any preceding claim, wherein the end-effector comprises at least one attachment body in addition to the manual interaction bodies, the attachment body comprising at least one attachment point at which at least one of the actuator cables is attached to the end- effector.
16. The cable driven robot of any preceding claim, wherein the end-effector comprises at least one attachment body in addition to the manual interaction bodies, the attachment body comprising at least one attachment point at which a plurality of the passive cables are attached.
17. A method of using a cable driven robot, the cable driven robot comprising:
an end-effector; and
a plurality of actuator cables, each having one end connected to the end-effector, wherein the end-effector comprises:
a plurality of manual interaction bodies; and a plurality of passive cables connecting the manual interaction bodies.
18. The method of claim 17, comprising:
adjusting the length and tension of the actuator cables so as to provide haptic feedback to a user interacting with the manual interaction bodies.
PCT/GB2020/051172 2019-05-15 2020-05-14 Cable driven robot WO2020229825A1 (en)

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GB1906857.6 2019-05-15

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Citations (4)

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