Multi-bar linkage, lower-limb exoskeleton robot using the same, and method of controlling the same

Patent metadata

Field	Value
Publication number	US-10792811-B2
Application number	US-201715824532-A
Country	US
Kind code	B2
Filing date	Nov 28, 2017
Priority date	Jun 30, 2017
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A multi-bar linkage includes a driving unit that is configured to supply torque to a driving shaft, where the driving shaft is provided on a first portion of a first link. A driving arm has one end fixed to the driving shaft and an opposite end being movable following rotation of the driving shaft. A first auxiliary link has one end pivotably connected to the opposite end of the driving arm. A second auxiliary link is pivotably connected to a first point of a second portion of the first link and to an opposite end of the first auxiliary link. A second link is disposed below the first link and pivotably connected to the second auxiliary link. A third auxiliary link has one end pivotably connected to a second point of the second portion of the first link, separated from the first point, and an opposite end pivotably connected to the second link.

First claim

What is claimed is:

1. A multi-bar linkage, comprising:
a driving unit supplying torque to a driving shaft;
a first link, wherein the driving shaft is provided on a first portion of the first link;
a driving arm having one side fixed to the driving shaft and an opposite side being movable following rotation of the driving shaft;
a first auxiliary link having one side pivotably connected to the opposite side of the driving arm;
a second auxiliary link pivotably connected to a first point of a second portion of the first link and pivotably connected to an opposite side of the first auxiliary link;
a second link disposed below the first link and pivotably connected to the second auxiliary link; and
a third auxiliary link having one side pivotably connected to a second point of the second portion of the first link, separated from the first point of the second portion of the first link, and an opposite side pivotably connected to the second link,
wherein the second auxiliary link has a contact surface, with which a lower side portion of the first link comes into contact, and the lower side portion of the first link slides on the contact surface when the driving shaft rotates, and
wherein the second auxiliary link comprises a guide forming the contact surface and a connecting portion fixed to one side of the guide, the connecting portion being pivotably connected to the first link and the first auxiliary link, and an opposite side of the guide being pivotably connected to the second link.

2. The multi-bar linkage according to claim 1 , wherein the lower portion of the first link comprises a curved surface, and the contact surface comprises a surface concavely curved in a direction of the first link.

3. The multi-bar linkage according to claim 1 , wherein the guide comprises roller bearings on the contact surface.

4. The multi-bar linkage according to claim 1 , further comprising a controller controlling the driving unit by determining torque of the driving shaft based on an angle of rotation detected from the driving arm.

5. The multi-bar linkage according to claim 4 , wherein the controller performs:
detecting the angle of rotation of the driving arm;
deriving an angle of a knee joint, as an angle between the first link and the second link corresponding to the detected angle of rotation of the driving arm, and a ratio between an angular speed of the knee joint and an angular speed of rotation of the driving arm, by applying a preset mapping function and a preset speed ratio, and deriving an angular speed of rotation of the driving art by differentiating the detected angle of rotation of the driving arm;
deriving an angular speed of the knee joint corresponding to the detected angle of rotation of the driving arm, using the ratio between the detected angular speed of rotation of the driving arm and the ratio between the angular speed of the knee joint and the angular speed of rotation of the driving arm;
deriving torque of the knee joint, as a torque of rotation of the second link based on the first link, using the derived angle of the knee joint and the derived angular speed of the knee joint; and
determining the torque of the driving shaft, using the derived ratio between the angular speed of the knee joint and the angular speed of rotation of the driving arm and the derived torque of the knee joint, and driving the driving unit to output the determined torque of the driving shaft.

6. The multi-bar linkage according to claim 5 , wherein the mapping function is predetermined by a formula:
θ k =f (θ a ),

where θ a is the angle of rotation of the driving arm, and θ k is the angle of the knee joint, and
the ratio between the angular speed of the knee joint and the angular speed of rotation of the driving arm is predetermined by differentiating and arranging both sides of the formula of the mapping function with respect to time so as to be expressed by a formula:

θ
.

k

θ
.

a

=

df
⁡

(

θ
a

)

d
⁢

⁢

θ
a

.

7. The multi-bar linkage according to claim 6 , wherein the controller determines the torque of the driving shaft by a torque calculation formula:

τ
a

=

θ
.

k

θ
.

a

⁢

τ
k

=

df
⁡

(

θ
a

)

d
⁢

⁢

θ
a

⁢

τ
k

,

wherein the torque calculation formula is determined, on an assumption that energy of the driving shaft is preserved as energy of rotation of the second link, by
establishing an energy preservation formula:
τ k {dot over (θ)} k =τ a {dot over (θ)} a ,

where τ k is the torque of the knee joint, τ a is the torque of the driving shaft, {dot over (θ)} k is the angular speed of the knee joint, and {dot over (θ)} a is the angular speed of the driving arm, and
dividing both sides of the energy preservation formula by the angular speed of the driving arm.

8. A method of controlling the multi-bar linkage as claimed in claim 1 , the method comprising:
detecting the angle of rotation of the driving arm;
deriving an angle of a knee joint corresponding to the detected angle of rotation of the driving arm, as an angle between the first link a

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp
• Hyundai Rotem Co

Inventors

• Hyun Dong Jin
• Ha Tae Jun
• Park Hyun Seok

Classifications

• B25J9/1065

  with parallelograms · CPC title

• B25J11/00

  Manipulators not otherwise provided for · CPC title

• B25J9/108

  Bearings specially adapted therefor (bearings in general F16C) · CPC title

• B25J9/106

  with articulated links · CPC title

• B25J9/1633 Primary

  compliant, force, torque control, e.g. combined with position control · CPC title