Spherical linkage and force feedback controls

A user interface system comprises a plurality of linkages connected between a platform and a base. The linkages permit motion of the platform over at least a portion of a spherical surface. A support assembly coupled between the platform and the base comprises a spherical joint having a center of rotation substantially concentric with a center of the spherical surface. The spherical joint constrains motion of the platform to the spherical surface. The system may include a sensor corresponding to each linkage. Each sensor may be coupled to sense a movement of its corresponding linkage in response to motion of the platform over the portion of the spherical surface. A user-manipulable handle may be coupled to the platform so that the user can move the platform.

TECHNICAL FIELD

The invention relates to input force feedback controls. Some embodiments provide force feedback controls that include a moveable handle or other grippable member for use in input devices of user interface systems, haptic systems or the like.

BACKGROUND

Robotic systems may be controlled by corresponding user interfaces. Some user interface systems permit users to control robotic systems by manipulating an interface member (e.g. a grippable handle or the like) in space to provide control information to the robotic system. Some user interface systems allow users to manipulate virtual objects by manipulating an interface member.

In such user interface systems, it is often desirable to provide the user with force feedback. User interface systems incorporating force feedback are referred to in the art as “haptic systems” or “haptic devices”. Force feedback can allow the user to experience the sensation of feeling virtual objects that the user is interacting with by way of the user interface and can provide improved user control over the forces applied by a corresponding robotic system.

There is a need for haptic user interface systems and other force feedback devices which provide force feedback to a user.

DESCRIPTION

FIG. 1shows a force-feedback10according to an embodiment of the invention. Device10comprises a hand-operated handle assembly12, which may be used by a user to interact with device10. Handle assembly12is supported on a platform14by shaft50. Device10comprises a mechanism16that permits platform14to move in multiple dimensions. In the illustrated embodiment, mechanism16comprises a plurality of linkages18A,18B,18C (collectively, linkages18) which allow platform14to be moved over a portion of a surface of an imaginary sphere centred at point28A. Mechanism16provides platform16with three degrees of freedom q, f, y shown inFIG. 1A.

FIG. 2shows theFIG. 1device10without linkages18. Device10comprises a support assembly24which, in theFIG. 2embodiment, extends between base surface32and platform14to support platform14. In device10, base surface32is provided by base member31. In some embodiments, base member31is not required and base surface32may be the surface on which device10is standing. Base surface32may be relatively flat.

Support assembly24comprises a support joint28between support members26,30. Support joint28is a spherical joint having a centre of rotation28A. The center of rotation28A of spherical joint28is concentric with the sphere about which mechanism16permits movement of platform14. In device10, spherical support joint28incorporates a ball34between support members26,30and support members26,30have corresponding concave sockets (not visible) which allow support members26,30to move independently relative to ball34. A portion of each of the concave sockets of support members26,30may be spherically concave with a radius of curvature that is substantially similar to that of ball34, such that spherical support joint28resists motion of support members26,30in a radial direction relative to centre of rotation28A.

In other embodiments, a first one of support members26,30is fixed relative to ball34and need not incorporate a concave socket. In such embodiments, the second one of support members26,30incorporates a concave socket for movement relative to ball34. A portion of the concave socket on the second one of support members26,30may be spherically concave with a radius of curvature that is substantially similar to that of ball34. In other embodiments, spherical support joint28is implemented without ball34. In such embodiments, a first one of members26,30comprises a convex surface and the other one of members26,30comprises a concave socket. A portion of the convex surface may be spherically convex and a portion of the concave socket may be spherically concave with substantially similar radii of curvature.

As used herein, the term “spherical joint” (including “spherical support joint”) means a joint which facilitates movement of at least one element such that a point within the element moves over at least a portion of a spherical surface that is centred at a centre of rotation and wherein the joint resists movement of the point in a radial direction relative to the centre of rotation. Together, mechanism16and spherical joint28permit platform14to move about the surface of an imaginary sphere having a radius r (FIG. 1A) centred at the centre of rotation28A of spherical support joint28(i.e. platform14is permitted to move in the angular directions θ, φ, ψ ofFIG. 1A). Spherical joint28constrains the motion of platform14to this spherical surface by resisting movement of platform14in a radial direction relative to centre of rotation28A. During movement of platform14, support member26moves relative to support member30such that platform14remains a fixed distance r from the centre of rotation28A of spherical support joint28. Preferably, spherical support joint28provides minimal resistance to movement of platform14in the angular directions θ, φ, ψ. As explained in more detail below, support24and spherical support joint28prevent mechanism16and linkages18from binding and allow system10to provide a user with improved force feedback.

FIG. 3Ashows an overhead view of system10with handle assembly12and some of its other components removed. As shown inFIG. 3A, mechanism16incorporates linkages18which moveably couple platform14to mounts36A,36B,36C (collectively, mounts36). Mounts36may optionally be rigidly connected to base surface32. Each of linkages18comprises a pair of links, which include:primary links20A,20B,20C (collectively, primary links20) pivotally coupled to platform14at primary pivot joints22A,22B,22C (collectively, primary pivot joints22) for pivotal movement about primary pivot axes38A,38B,38C (collectively, primary pivot axes38); andsecondary links40A,40B,40C (collectively, secondary links40) pivotally coupled at their first ends to mounts36at pivot joints42A,42B,42C (collectively, secondary pivot joints42) for pivotal movement about secondary pivot axes44A,44B,44C (collectively, secondary pivot axes44) and at their second ends to primary links20at intermediate pivot joints46A,46B,46C (collectively, intermediate pivot joints44) for pivotal movement about intermediate pivot axes48A,48B,48C (collectively, intermediate pivot axes48).

In system10, primary pivot axes38, secondary pivot axes44and intermediate25pivot axes48intersect at point28A (i.e. the centre of rotation28A of spherical support joint28). As platform14moves about a portion of an imaginary spherical surface centred at point28A (i.e. in the angular directions θ, φ, ψ ofFIG. 1A), primary links20and secondary links40pivot to different orientations about primary pivot axes38, secondary pivot axes44and intermediate pivot axes48. In system10,30mechanism16may operate such that regardless of the configuration of linkages18, a radial line r (FIG. 1A) extending between central point28A and platform14that intersects platform14at a particular location will pass through platform14with the same orientation.

Handle assembly12is mounted on platform14via shaft50. A user may exert force on platform14through handle assembly12. Such force may generally be oriented in any direction and may cause movement of platform14in the angular directions θ, φ, ψ as discussed above. In response to such applied force, the corresponding movement of mechanism16will typically require the simultaneous movement of a number of pivot joints22,42,46(i.e. unless the applied force happens to be oriented to coincide exactly with pivotal movement of one of pivot joints22,42,46). In addition, applied force may tend to move platform14off of the spherical surface over which mechanism16permits movement. In such circumstances (i.e. under a load which has a tendency to cause simultaneous movement of a number of pivot joints22,42,46and/or under a load which tends to move platform14off of the spherical surface over which mechanism16permits movement), mechanism16may be susceptible to binding at one or more of pivot joints22,42,46.

Support assembly24acts to counter force applied in a radial direction (relative to centre of rotation28A) and to constrain the motion of platform14to the angular directions θ, φ, ψ, thereby reducing the chance that one or more of linkages18will bind at pivot joints22,42,46. Since spherical support joint28is also capable of facilitating relative movement of support member26in any direction that platform14is capable of moving (i.e. in the angular directions θ, φ, ψ), spherical support joint28is unlikely to bind under the application of force.

For each linkage18in mechanism16, system10comprises a corresponding motor52A,52B,52C (collectively, motors52) or some other suitable actuator and a corresponding sensor54A,54B,54C (collectively, sensors54). Motors52are operationally coupled to secondary pivot joints42to apply torques which would tend to pivot secondary links40about secondary axes44. In system10, motors52are operationally coupled to secondary pivot joints42, via sectors56A,56B,56C (collectively, sectors56) which are coupled to pivot with secondary links40. Sectors56have corresponding arcuate sides58A,58B,58C (collectively, arcuate sides58) which are operationally connected to the shafts (not shown) of motors52. Sectors56(may be coupled to the shafts of motors52by suitable gear mechanisms, pulley and cable mechanisms, friction-based mechanisms or the like. In a particular embodiment, tendons (not shown) are wrapped around the shafts of motors52(or around pulleys coupled to move with the shafts of motors52) and are rigidly connected to sectors56, such that movement of the shafts of motors52causes the tendons to pull on sectors56and causes corresponding pivotal motion of secondary links40(and pivot joints42) about secondary axes44.

Sensors54are connected to detect the angular positions of secondary links40about secondary axes44. Sensors54may be connected to the shafts of motors52or to other components in the operative connection between the shafts of motors52and secondary pivot joints42. Sensors54may comprise rotary encoders. Motors52and sensors54may respectively comprise the motor and sensor components of servomotors. A computer or other processing device (e.g. processor712ofFIG. 8discussed in more detail below) may be connected to receive position signals from sensors54(i.e. signals corresponding to the positions of secondary links40about secondary axes44). When a user moves handle assembly12and causes corresponding movement of platform14in the angular directions θ, φ, ψ, the processor may use the position signals from sensors54to determine drive signals for motors52to provide the user with force feedback.

Those skilled in the art will appreciate that there are a wide variety of ways in which a motor can be operationally coupled to drive a component about a pivot axis implemented by a pivot joint and to provide a corresponding sensor for detecting the angular position of the component about the pivot axis. The invention should be understood to accommodate any suitable mechanism(s) for operationally coupling motors52to secondary links40or to pivot joints42so as to drive secondary links40about pivot axes44and any suitable arrangement for coupling a sensor to detect the motion of secondary links40or pivot joints42about pivot axes44.

When device10is used to provide force feedback as a part of a haptic system, it is desirable for device10to be transparent to the user, such that the user can use handle assembly12to move platform14in the angular directions θ, φ, ψ and experience a feeling of force-feedback through handle assembly12that is independent of the mechanism16used to facilitate movement of platform14. When using a transparent force feedback device, a user will not feel reaction forces from friction and inertia of the device (e.g. the components of mechanism16) and will only feel the forces applied by the force feedback actuators (e.g. motors52). A force feedback device with a high degree of transparency may be referred to as a high fidelity force feedback device.

Clearly, if mechanism16binds when handle assembly12is operated by a user, then device10is not acting in a transparent manner. As discussed above, support assembly24(including spherical support joint28) reduce the chances that mechanism16will bind during movement of platform14, thereby improving the fidelity of device10. Support24(and spherical support joint28) also improve the fidelity of device10by reducing the friction, deadweight and inertia in mechanism16(i.e. in links20,40and pivot joints22,42,46). In some embodiments, linkages18can be made from lighter materials, since linkages18are not required to support platform14against forces applied by a user in the radial direction. The reduction in friction, deadweight and inertia of mechanism16improve the ability of a user to manipulate platform14via handle assembly12(i.e. movement of mechanism16will be more responsive (e.g. in speed and accuracy) to forces applied by the user). In addition, the reduction in friction, deadweight and inertia of mechanism16improve the ability of motors52or provide force feedback to a user (i.e. movement of mechanism16will be more responsive (e.g. in speed and accuracy) to forces applied by motors52).

The dimensions of device10(and in particular the dimensions of mechanism16) maybe selected to provide sufficient strength while permitting platform14to be moved through the desired range of angles θ, φ, ψ.

Handle assembly12of device10comprises finger grips102A,102B (collectively, finger grips102) through which a user may insert their fingers to manipulate device10. Finger grips102are supported by ring104. Using finger grips102, a user may manipulate platform14in the angular directions θ, φ, ψ as discussed above.

As shown most clearly inFIGS. 2 and 3B, handle assembly12may provide device10with a number of additional degrees of freedom. Using finger grips102, a user may cause handle assembly12to move inwardly and outwardly along the longitudinal shaft axis (as indicated by double-headed arrow110) of shaft50. In device10, handle assembly12is mechanically coupled to a motor114(or other actuator) by linkage118and sensor116is provided to detect the position of handle assembly12along longitudinal shaft axis110. In this manner, a processor can receive position information from sensor116and can drive motor114to provide the user with force feedback that counters the movement of handle assembly12in either direction along longitudinal shaft axis110.

As shown best inFIG. 3B, shaft50of device10comprises: an exterior shaft member55; a slot57which runs along the longitudinal dimension of exterior shaft member55; and an interior shaft member59which is slidably moveable within exterior shaft member55along longitudinal shaft axis110. Handle assembly12is coupled to move with interior shaft member59along longitudinal shaft axis110.

In device10, linkage118which couples handle assembly12to motor114comprises a longitudinal shaft coupling arm118A which extends in a direction substantially parallel to shaft50. Transverse shaft coupling arm118B connects longitudinal shaft coupling arm118A (through slot57) to interior shaft member59.

Motor engaging component118C is coupled between motor114and longitudinal shaft coupling arm118A so as to transfer torque from motor114to shaft coupling arm118A and to thereby apply linear force to handle assembly in one of the directions of longitudinal shaft axis110. In some embodiments, the coupling between shaft coupling arm118A and motor engaging component118C is implemented with a friction coupling. In other embodiments, shaft coupling arm118A and motor engaging component118C may comprise pulleys and cables, gears or the like. In one particular embodiment a tendon (not shown) is wrapped around the shaft of motor114(or around a pulley coupled to move with the shaft of motor114) and is rigidly coupled to shaft coupling arm118A, such that movement of the shaft of motor114causes the tendon to pull on shaft coupling arm118A and causes corresponding translational motion of handle assembly12along the longitudinal shaft axis110.

Those skilled in the art will appreciate that there are a wide variety of ways in which a motor can be operationally coupled to drive a component in a translational manner and to provide a corresponding sensor for detecting the translational position of the component. The invention should be understood to accommodate any suitable mechanism(s) for operationally coupling a motor114to exert force on handle assembly12in the direction of longitudinal shaft axis110and any suitable arrangement for coupling a sensor to detect the motion of handle assembly12.

Handle assembly12may provide other degrees of freedom. By way of non-limiting example: a user may pivot finger grips102and ring104about the longitudinal axis110of shaft50as indicated by double-headed arrow112; a user may pivot finger grips102relative to ring104about axis122as indicated by double-headed arrow120; a user may move finger grips102toward one another and/or away from one another as indicated by double-headed arrow124; and a user may pivot finger grips126within ring104as indicated by double-headed arrow126.

Each of these movements of handle assembly12may be facilitated by a suitably configured mechanical joint (not shown), such as a pivot joint or a suitably configured mechanism (not shown) capable of providing translational movement, for example. Sensors (not shown) may be connected to detect the configuration of these joints and/or mechanisms (e.g. the pivotal orientation of a pivot joint and/or the translational orientation of a translation mechanism). Motors or other actuators (e.g. motors117A,117B) may be operationally coupled to pivot and/or translate finger grips102and/or ring104using these joints and/or mechanisms. A computer or other processor can receive position information from the sensors and use the motors to provide the user with force feedback through these joints and/or mechanisms.

Spherical support joint28may generally be supported using any suitable support assembly. In device10, spherical support joint28is supported on the end of a centrally-located, vertically-extending support member30.FIG. 4Ais a partial view of a force feedback device210according to another embodiment of the invention. Some of the components of device210are not shown inFIG. 4Ato provide a view of support assembly224, wherein ball234of spherical support joint228is supported by an arm230that is cantilevered from mount236A. In other respects, spherical support joint228is similar to spherical support joint28of device10. Device210incorporates a mechanism216(similar to mechanism16of device10) which permits platform214to be moved about an imaginary spherical surface.

As with device10, the spherical support joint228of device210is located such that its centre of rotation is coincident with the centre of the imaginary sphere about which platform14can move (i.e. the point of intersection of the primary, secondary and intermediate axes of mechanism216. Spherical support joint228may act in a manner substantially similar to spherical support joint28of device10to prevent binding of mechanism216and to reduce the friction, deadweight and inertia of mechanism216, thereby improving the fidelity of the force feedback provided by device210.

It is not generally necessary that arm230of spherical support joint228be cantilevered from the same mount236A that holds motor252A.FIG. 4Bshows a device210′ according to another embodiment of the invention. Some of the components of device210′ are not shown inFIG. 4Ato provide a view of support assembly224′, wherein ball234′ of spherical support joint228′ is supported by an arm230′ that is cantilevered from its own mount235′.

Those skilled in the art will appreciate that there are other arrangements for supporting a spherical support joint with its centre of rotation located at the intersection of the primary axes38, secondary axes44and intermediate axes48. Preferably, the structure provided to support the spherical support joint does not unduly limit the range of motion of platform14by interfering with mechanism16.

Spherical support joint28maybe implemented using other constructions. In device10, spherical support joint28is implemented using a ball34and at least one support member with a concave socket (i.e. a ball and socket construction).FIG. 5is a partial view of a force feedback device310according to another embodiment of the invention. Some of the components of device310are not shown inFIG. 5to provide a view of spherical support joint328which comprises a three degree of freedom (3-DOF) joint327. 3-DOF joint327comprises: an optional support member326that is rigidly connected to platform314; a joint body357that is pivotally coupled to support member326(or to platform314) at a first pivot joint355for relative pivotal movement between support member326(or platform314) and joint body357about a first pivot axis351as indicated by double-headed arrow353; a second pivot joint343for relative pivotal movement between joint body357and support member329about a second pivot axis345as indicated by double-headed arrow347; and a third pivot joint337for relative pivotal movement between joint body357and support member335about a third pivot axis339as indicated by double-headed arrow341.

In the illustrated embodiment, 3-DOF joint327is configured such that pivot axes339,345,351are orthogonal to one another and is located such that pivot axes339,345,351intersect at point328A, which is the centre of the sphere about which mechanism316permits movement (i.e. the same point328A of intersection of the primary, secondary and intermediate axes of mechanism316). Together, 3-DOF joint327and mechanism316permit the movement of platform314in the angular directions θ, φ, ψ about an imaginary sphere having a radius r and centred at point328A. 3-DOF joint327has the characteristics of a spherical support joint discussed above. More specifically, 3-DOF joint327constrains movement of platform314such that platform314is able to move over at least a portion of a spherical surface that is centred at a centre of rotation328A is prevented from moving in a radial direction relative to the centre of rotation328A.

In a manner similar to that in which ball and socket joint28(together with supports26,30) support mechanism16(FIGS. 1-3B), 3-DOF joint327(together with support members326,329,335) support mechanism316to reduce the chances of mechanism316binding and to reduce the friction, deadweight and inertia of mechanism316. 3-DOF joint327provides the additional feature that longitudinal shaft350which connects handle assembly312to platform314can project through platform314and through the centre of rotation328A.

Handle assembly12may be implemented using other alternative handle apparatus. As explained above, in device10ofFIGS. 1-3B, handle assembly12comprises a pair of finger grips102housed within a ring104, which permits finger grips102to move with a number of additional degrees of freedom (i.e. about the longitudinal shaft axis110(double-headed arrow112); about axis122(double-headed arrow120); toward one another and/or away from one another (double-headed arrow124); and within ring104(double-headed arrow126)).

FIG. 6Adepicts a force feedback device410according to another embodiment of the invention wherein handle assembly412comprises a handle member452having a pair of finger grips454A,454B (collectively, finger grips454) that are fixed relative to one another. In device410, handle member452may move backward and forward along the direction of the longitudinal axis (as indicated by double-headed arrow456) of shaft450and may pivot about the longitudinal axis456of shaft450(as indicated by double-headed arrow458).

Device410incorporates a sensor462connected to detect the position of handle member452along longitudinal shaft axis456and to provide this position information to a processor. Device410also incorporates a motor460(or other actuator) operationally coupled to drive handle member452along longitudinal shaft axis456to provide force feedback to handle member452. The operation of sensor462and motor460may be substantially similar to motor114and sensor116of device10(FIGS. 1-3B). Device410may also incorporate one or more sensors (not shown) for detecting the pivotal orientation of handle member452about longitudinal shaft axis456and one or more actuators (not shown) operationally coupled to handle member452for providing force feedback to the movement of handle member452about longitudinal shaft axis456. A computer or other processor (not shown) may be used to receive position information from the sensors and to provide drive signals to the motors (or other actuators).

In other embodiments, handle assembly412may incorporate one or more additional pivot joints (not shown) which permit one or both of finger grips454to move toward or away from one another as indicated by double-headed arrow464. The one or more additional pivot joints may be located at the junction466of arms468A,468B for example. The one or more pivot joints may also be provided with one or more suitably connected sensors and one or more suitably connected actuators which permit force feedback to the movement of finger grips454toward and/or away from one another.

FIG. 6Bdepicts a force feedback device510according to another embodiment of the invention. Device510differs from the previously described embodiments in that device510comprises a spherical support joint528that is located between platform514and handle assembly512. In the illustrated embodiment, spherical support joint528of device510comprises a 3-DOF joint527(similar to 3-DOF joint327of device310(FIG.5)), such that shaft550of handle assembly512is capable of projecting through spherical support joint528.

Handle assembly512of device510comprises a handle member552having a pair of finger grips554A,554B (collectively, finger grips554). Handle member552is coupled to shaft550via a secondary joint570. Secondary joint570permits movement of handle member552relative to shaft550in the orthogonal angular directions θ and φ indicated by double-headed arrows572and574. The movement of handle member552provided by secondary joint570may be similar to that of a joystick. Device510may comprise one or more sensors (not shown) connected to detect the angular position of handle member552relative to secondary joint570and/or shaft550and one or more motors or other actuators (not shown) operationally coupled to handle member552to provide force feedback to the motion of handle member552in the angular directions θ and φ indicated by double-headed arrows572and574.

In the embodiment illustrated inFIG. 6B, finger grips554are rigidly coupled to handle member552. In other embodiments, one or both of finger grips554may be coupled to one or more pivot joints for pivotal movement relative to handle member552and/or relative to the other one of finger grips554. One or more suitably connected sensors and actuators may be connected to provide force feedback to such pivot joints. As with the previously described embodiments, handle assembly512maybe translated in either direction along longitudinal shaft axis556and maybe pivoted about longitudinal shaft axis56in the directions indicated by double-headed arrow558. One or more suitably connected sensors and actuators may be connected to provide force feedback to such translation of handle assembly512and to such pivotal movement of handle assembly552.

Mechanisms different from mechanism16maybe used to permit movement of platform14in the angular directions θ, φ, ψ (FIG. 1A).FIG. 7Adepicts a partial view of a force feedback device610according to another embodiment of the invention. Device610comprises a different mechanism616for facilitating movement of platform614in the angular directions θ, φ, ψ (i.e. about the x, y and z axes ofFIG. 1A), with an origin corresponding to the centre628A of a spherical support joint628. Spherical support joint628constrains the movement of platform614to the surface of an imaginary sphere centred at centre of rotation628A. Some of the components of device610(e.g. sensors) are not shown inFIG. 7Ato provide a better view of mechanism616.

Mechanism616of device610comprises three linkages618A,61813,618C (collectively, linkages618) which are coupled to holding mount632at one of their ends and to platform614at their opposing ends. In device610, linkages618are coupled to holding mount632and to platform614at evenly angularly-spaced apart locations (i.e. 120° apart). Linkages618each comprise six links interconnected by a plurality of in-plane pivot joints to provide a spherical mechanism616. Mechanism616provided by linkages618permits platform614to be moved (via user actuation of handle612) in the angular directions θ,100, ψ (i.e. about the x, y and z axes ofFIG. 1A) with an origin corresponding to the centre of rotation628A of spherical support joint628.

FIG. 7Bdepicts linkage618A in more detail. It will be appreciated that linkages618B,618C are substantially similar to linkages618A. Linkage618A comprises a rod615A which is rigidly coupled at one of its ends to platform614(not shown inFIG. 7B) and at its opposing end to spherical connection613A. Linkage also comprises a fitting617A which is rigidly coupled at one of its ends to link619A and at its opposing end to spherical connection613A. Linkage618A comprises six links619A,621A,623A,625A,627A and629A which are interconnected by seven in-plane pivot joints631A,633A,635A,637A,639A,641A and643A. Link627A is operationally coupled to a shaft645A of motor (or other actuator)647A. Actuator647A is rigidly coupled to holding mount632(not shown inFIG. 7B). When shaft645A of actuator647A pivots (i.e. about axis651A), linkage618A will pivot into and/or out of the page (i.e. about the axis651A of link627A).

FIG. 7Balso shows that the axis651A of link627A and the axis653A of link619A intersect at a point628A. Spherical support joint628is located such that the point628A of intersection of axes651A and653A is coincident with the centre of rotation of spherical support joint628A. This property of linkage618A is true for all permitted configurations of linkage618A and platform614. Linkages618B and618C exhibit similar properties. More specifically, linkage618B comprises a pair of links627B,619B having axes651B,653B that intersect at centre of rotation628A and linkage618C comprises a pair of links627C,619C having axes651C,653C that intersect at centre of rotation628A.

In linkage618A, links619A,621A,623A,625A,627A and629A are substantially straight, although this is not necessary. In linkage618A, central links621A,625A maybe approximately twice the length of exterior links619A,623A,627A,629A. Pivot joints631A,633A,635A,637A,639A,641A and643A of linkage618A are in-plane pivot joints, which means that their respective pivot axes are parallel with one another. Those skilled in the art will appreciate that sensors (not shown) could be operationally coupled to axis645A of actuator647A and/or to one or more of pivot joints631A,633A,635A,637A,639A,641A and643A and/or to links619A,621A,623A,625A,627A and629A and could be used in conjunction with actuator647A to provide force-feedback to linkage618A in a manner similar to that discussed above.

Device610comprises three mounts651A,651B,651C (collectively, mounts651) which are connected to holding mount632at one of their ends and which extend away from holding mount632toward base surface653on which device610is standing. Mounts651,632bear the weight of device610and hold up device610on base surface653. In device610ofFIG. 7A, support assembly624comprises a support assembly similar to support assembly24of device10FIGS. 1-3B). More particularly, support assembly624comprises: a ball-type spherical joint628(see ball634); a first support member630that extends from base surface653to ball634; and a second support member626that extends from ball634to platform614. In other respects, device610may be substantially similar to any of the force feedback devices discussed above and may have similar variations in respect of the handle assemblies, spherical support joints, and support assemblies as any of the force feedback devices discussed above.

FIG. 8is a schematic diagram showing an application of the invention in a haptic system700. Haptic system700represents only one exemplary and non-limiting application of the devices described herein. Those skilled in the art will appreciate that theFIG. 8diagram is schematic and high-level in nature and that some components of system700are omitted for clarity. Haptic system includes a force feedback device706which may be implemented in accordance with any of the embodiments described herein. Force feedback device706is coupled to a processor712. In haptic system700, processor712is coupled to an external system718that operates in a workplace720. The objective of haptic system700is to permit a user to control the operation of external system718in workplace720using force feedback device706. In some alternative applications, external system718and workplace720can be modeled by processor712.

A user interacts with force feedback device702(e.g. by manipulating a handle assembly) and causes movement of various components of force feedback device706. For example, a user may cause the platform of device706to move in the angular directions θ, φ, ψ as discussed above. The movement of the component(s) of device706is detected by sensors and provided as sensor output information708to processor712. Processor712is provided with a control model of force feedback device706and a control model of external system718. Using these control models, processor712determines motor drive signals716that are provided to drive the components of external system718and to operate external system718in workplace720.

When external system718operates in workplace720(i.e. the components of external system718move within workplace720), external system718interacts with workplace720. During such interaction, forces may be applied by workplace720to the components of external system718. For example, external system718may be a robot performing a medical procedure on a workplace720that is a human patient. One of the components of robot718may touch the patient's liver and experience a certain force level and then encounter the patient's rib and experience a different force level.

Such different force levels may manifest themselves as different position responses to motor drive signals716. For example, if a component of system718was moving though liver, then it may move a certain distance in response to a given drive signal level, but when the component encounters bone, it may move much less in response to the same drive signal. These position responses are detected by sensors in external system718and are provided to processor712as sensor output714. Using its control models for force feedback device706and external system718, processor determines motor drive signals710which are provided to drive the motors of force feedback device706.

In response to receiving the motor drive signals710, the motors of force feedback device706apply force to the component(s) of force feedback device706and thereby provide the user with force feedback704as discussed above. This force feedback704can enable the user interacting with force feedback device706to experience the sensation of “feeling” a virtual object. In the example provided above, the user will experience greater force feedback when external system718encounters a patient's bone as opposed to the patient's liver and will therefore “feel” a virtual rib.

It will be appreciated by those skilled in the art that the force feedback704provided by system700is most useful when the force feedback704is provided as quickly as possible and where force feedback device706is transparent to the user (i.e. the user feels as though he or she is actually operating external system718in workplace720). As discussed above, the support assembly (including the spherical support joint) of the force feedback devices described herein improves the fidelity and transparency of the force feedback devices.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example:

In some embodiments of the invention, brakes may be provided to supply force-feedback to a user in addition to or instead of motors. Linear actuators may also be provided in addition to or instead of pivotal actuators.

The handle assemblies described in connection with the devices discussed herein are optional. In alternative embodiments, a user may directly manipulate the platforms of the various devices with some part of the user's body.

The platforms of the force feedback devices disclosed herein need not be solid components. The platforms are preferably something on which a handle assembly can be mounted.

In the illustrated embodiments described herein, spherical joints are implemented using ball and socket joints or 3-DOF joints. Those skilled in the art will appreciate that other embodiments of the invention may make use other spherical joints having the characteristics described above. By way of non-limiting example, a spherical joint having the characteristics discussed above may comprise a first member having a convex surface and a second member having multiple contact points, wherein the multiple contact points are located about an imaginary concave surface, such that the contact points can slideably engage the convex surface of the first member. A portion of the convex surface may be spherically convex and the contact points may be located about an imaginary spherically concave surface. As another non-limiting example, a spherical joint having the characteristics discussed above may comprise a first member having a concave surface and a second member having multiple contact points, wherein the multiple contact points are located about an imaginary convex surface such that the contact points can slideably engage the concave surface of the first member.

The embodiments described above depict devices that can be operated by a user using a single hand. In some embodiments of the invention, a pair of devices (each similar to one of the above-described devices) is provided to be controlled by each of a user's hands.

As discussed above, device510ofFIG. 6Bcomprises a spherical joint528that is located between platform514and handle assembly512. In device510, spherical support joint528of device510comprises a 3-DOF joint527, such that shaft550of handle assembly512is capable of projecting through spherical support joint528. In other embodiments where the spherical support joint is located between the platform and the handle assembly, the shaft of the handle assembly is offset from centre, such that it does not pass through the centre of rotation of the spherical support joint.

Haptic system700described above and shown inFIG. 8incorporates position sensors and make use of position sensor information only. In other embodiments, force feedback device706and/or external system718may comprise other types of sensors, such as pressure sensors, force sensors and the like which may be used in a manner similar to the position sensors to provide a user with improved force feedback.

In some embodiments, the devices described above can be used as input devices without force feedback. In such cases, the devices described above do not require motors or other actuators for providing force feedback. For example, system700ofFIG. 8can be modified such that processor712does not provide motor drive signals710to device706.

Haptic system700represents only one exemplary and non-limiting application of the devices described herein. In some applications, it is not necessary that processor712interact with an external system718or a workplace720. For example, processor712may be running a software model or software application, such as a video game. In response to sensor output signals708, processor712may provide motor drive signals710on the basis of information and/or instructions obtained from such software.

Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.