Complex mass trajectories for improved haptic effect
A haptic actuator includes mechanical links defining a first J-trajectory and mechanical links defining a second J-trajectory as well as a motor coupled to the mechanical links so as to synchronously accelerate a first mass over the first J-trajectory and a second mass over the second J-trajectory. During a first time interval, reactive forces of the first mass accelerating substantially balance reactive forces of the second mass accelerating and during a second time interval reactive forces of the first mass accelerating do not substantially balance reactive forces of the second mass accelerating. This un-balanced condition results in a tap signal being produced.
1. A haptic transducer comprising:
an inertial mass;
a mechanical linkage assembly, said mechanical linkage assembly being adapted to support said inertial mass for rotary motion about an axis of rotation; and
a latch mechanism, said latch mechanism being adapted to maintain said mechanical linkage in a first retained configuration during a first time interval and thereafter release said mechanical linkage into a second released configuration during a second time interval such that during said second time interval said inertial mass follows an arcuate path away from said axis of rotation and thereby accelerates said mechanical linkage along said axis of rotation so as to produce a haptic signal of said haptic transducer.
2. A haptic transducer as defined in claim 1 wherein said inertial mass comprises at least two inertial mass portions.
3. A haptic transducer as defined in claim 1 wherein said arcuate path away from said axis of rotation comprises a spiral helix path.
4. A haptic transducer as defined in claim 1 wherein said mechanical linkage comprises a rectangular four bar linkage.
5. A haptic transducer as defined in claim 1 wherein said latch mechanism comprises a magnetic latch mechanism.
6. A haptic transducer comprising:
an inertial mass;
a primary linkage, said primary linkage supporting said inertial mass for rotary motion about an axis of rotation;
a secondary linkage, said secondary linkage including a primary rotor, a secondary rotor, and a four bar spherical linkage, said primary rotor and said secondary rotor being supported for concentric rotation about said axis of rotation, said four bar spherical linkage being disposed between said primary rotor and said secondary rotor and operatively coupling said primary rotor to said secondary rotor;
a coupling member, said coupling member having a first end and a second end, said first end being coupled through said primary linkage to said inertial mass and said second end being coupled to said four bar spherical linkage, whereby when said four bar spherical linkage is arranged in a first linkage configuration, said inertial mass is disposed in a first mass configuration relatively proximate to said axis of rotation, and when said four bar spherical linkage is arranged in a second linkage configuration, said inertial mass is disposed in a second mass configuration relatively distal from said axis of rotation, and whereby a transition from said first mass configuration to said second mass configuration produces a haptic signal of said haptic transducer.
7. A haptic transducer as defined in claim 6 wherein said primary linkage comprises a four bar parallelogram linkage.
8. A haptic transducer as defined in claim 6 wherein said primary linkage comprises an Evans linkage.
9. A haptic transducer as defined in claim 8 further comprising a motor, said motor having a shaft, said shaft being disposed substantially coaxially with said axis of rotation.
10. A haptic transducer as defined in claim 9 wherein said shaft is coupled to said primary rotor of said secondary linkage.
11. A haptic transducer as defined in claim 10 wherein operating said motor in a first direction is adapted to place said four bar spherical linkage in tension between said primary rotor and said secondary rotor and wherein thereafter abruptly operating said motor in a second direction is adapted to place said four bar spherical linkage in compression between said primary rotor and said secondary rotor.
12. A haptic transducer as defined in claim 11 wherein transitioning said motor from operation in said first direction to operation in said second direction is adapted to move said inertial mass from said first mass configuration into said second mass configuration.
13. A haptic transducer as defined in claim 12 wherein said transition from said first mass configuration to said second mass configuration is adapted to produce a momentary acceleration of said haptic transducer.
14. A haptic transducer as defined in claim 13 wherein said momentary acceleration of said haptic transducer is substantially aligned with said axis of rotation.
15. A haptic transducer as defined in claim 14 wherein said shaft mutually supports said primary linkage and said secondary linkage.
16. A haptic transducer as defined in claim 6 further comprising a further inertial mass.
17. A haptic transducer as defined in claim 16 wherein said inertial mass and said further inertial mass are identical in mass.
18. A haptic transducer as defined in claim 6 wherein each of said primary linkage and said secondary linkage includes at least one substantially rigid layer of material and one substantially flexible layer of material.
19. A haptic transducer as defined in claim 6 wherein said inertial mass follows a substantially arcuate path from said first mass configuration to said second mass configuration.
20. A method of operating a haptic transducer comprising:
operating a rotary motor of said haptic transducer below a particular angular velocity to add angular momentum to an inertial mass while holding said inertial mass in a first configuration relatively proximal to a center of rotation of said inertial mass;
thereafter operating said rotary motor above said particular angular velocity so as to exceed a holding capacity of a latch mechanism and thereby transition said inertial mass to a second configuration relatively distal from said center of rotation;
operating a mechanical linkage to convert a measure of said angular momentum to a linear acceleration of said mechanical linkage; and
conveying a portion of said linear acceleration of said mechanical linkage to a housing of said haptic transducer to produce a haptic signal.