Parallel kinematic mechanisms with decoupled rotational motions

Abstract

A parallel kinematic mechanism apparatus includes a frame, a handle and an input joint that connects having at least two independent and functionally parallel paths for transmission of motion coupling the handle to the frame. A first path includes a first intermediate body connected to the frame by a first connector and to the handle by a third connector while the second path that is independent from the first path includes a second intermediate body that is connected to the frame by a second connector and to the handle by a fourth connector. The first connector and the fourth connector both allow rotation in a first rotational direction and restrict rotation in a second rotational direction and the second and third connectors allow rotation in the second rotational direction and restrict rotation in the first rotational direction.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 15 / 054,068, filed Feb. 25, 2016, titled “PARALLEL KINEMATIC MECHANISMS WITH DECOUPLED ROTATIONAL MOTIONS,” now U.S. Patent Application Publication No. 2016 / 0256232, which is herein incorporated by reference in its entirety.INCORPORATION BY REFERENCE[0002]All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.FIELD[0003]This invention relates to a minimal access tool, such as for surgery, endoscopy, or other interventions.BACKGROUND[0004]Devices, including minimally invasive surgical tools, may be controlled by controlling the motion of multiple rigid bodies forming the device. In machines, mechanisms, robots, etc., multiple rigid bodies are often in...

AI Technical Summary

Benefits of technology

The patent describes parallel kinematic mechanisms and apparatuses with at least two rotational degrees of freedom between a handle and a frame. These mechanisms use a constraint map to define the movements that can be transmitted between the handle and the frame. The mechanisms have at least two independent paths for transmitting motion, which allows for relative motion between the two bodies. The mechanisms can be used in minimally invasive tools and may include a tool shaft connected to the frame. The technical effects of the patent include improved control and precision in motion transmission between the handle and the frame, as well as reduced size and weight of the mechanisms.

Problems solved by technology

Minimally invasive surgical (MIS) and other minimal access procedures are increasing in frequency and becoming more complex, thus demanding improvements in technology to meet the needs of surgeons.

The traditional mechanical tools are difficult to use because of their lack of dexterity (i.e. the yaw and pitch rotational DoF).

While the newer tools are capable of enhanced dexterity given their extra two DoF, they present non-intuitive DoF control (input motion to output motion mapping) schemes that limit user's ability to fully exploit the tool's enhanced dexterity capability.

In addition, large size, high cost, and limited large-scale maneuverability also reduce the overall functionality of such robotic systems.

Therefore, most existing multiple DoF tools lack the design characteristics to allow for enhanced dexterity as well as desired functionality in a cost effective, compact package.

In particular, multiple DoF tools that allow for wrist-like rotations of the tool tip manipulator are important to meet the needs of modern minimal access and MIS procedures, but are not effective unless comfortable, ergonomic, and intuitive control of these additional DoF are ensured.

One challenge of using a serial kinematic mechanism design as the input joint of a surgical tool or machine or device is that of transmitting the two rotational DoF from the input joint to another location on the tool or machine or device.

Unfortunately, since the second axis itself rotates with respect to the frame about the first axis, it does not remain practical or easy to transmit the second rotation to a remote end effector on the frame.

Designing and building a transmission across any moving interface / joint is non-trivial, and adds significant complexity, cost, and the potential for failure.

These are some of the biggest limitations of a multi-DoF serial kinematic mechanism design.

Wireless does not require any physical transmission components, and so the drawback of the serial kinematic mechanisms described above are no longer relevant.

As a result serial kinematic mechanisms are common input joints or input interfaces for various computer or electronics based devices, but are somewhat challenging for purely mechanical devices.

To do this mechanically is very complicated, challenging, and generally impractical.

As a result serial kinematic mechanisms are common in devices / machines where electrical, electromechanical, hydraulic, or pneumatic actuation is involved, but are challenging as output joints of purely mechanical devices / machines.

Even in the former case, one drawback of a serial kinematic design is that the multiple actuators in the device / machine are not all mounted on the frame or the reference ground, and instead most move along with the DoFs.

This may make the machine large and bulky and require moving cable connections, which add to cost and machine size.

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