Assistance device and control method therefor
AssigneeBionicM Inc.
InventorXiaojun Sun
Life of this patent
Estimating the term…
Abstract
An assistance device is described to assist a joint motion of a lower limb. The assistance device includes a driving part, an elastic part, and a crank mechanism. The driving part includes a motor and a transmission mechanism to change a speed of the motor and converts a rotational motion of the motor into a linear motion. The elastic part includes at least: a series spring provided in series between the transmission mechanism and the crank mechanism, a first parallel spring provided between the driving part and the ankle part, and a second parallel spring provided between the ankle part and the foot part. The crank mechanism is provided between the driving part and the foot part and converts the linear motion to a rotational motion while changing a deceleration coefficient according to an ankle angle.
Claims11
An assistance device to assist a joint motion of a foot part, the device comprising:
- a driving part which comprises a motor and a transmission mechanism to change a speed of the motor, and converts a rotational motion of the motor into a linear motion;
- an elastic part which alleviates an impact from an object through the foot part and accumulates an impact force or self-gravity by compression, and releases an accumulated energy by stretching to apply an energizing force for motion assistance;
- and
- a crank mechanism which is provided between the driving part and the foot part, and an ankle part connected to the crank mechanism, the ankle part comprising a rotation shaft,
- wherein:
- the crank mechanism comprises a crank connected to and rotatable around the rotation shaft of the ankle part, and a rod with one end and the other end, the one end of the rod being connected to a leading end of the driving part, the other end of the rod being connected to the crank,
- and wherein:
- the crank mechanism is constituted so as to make one end of the rod on the side opposite to the driving part side to perform circulation motion, make the crank rotate around the rotation shaft of the ankle part, converts the linear motion into a rotational motion while changing a deceleration ratio by the crank, thereby transmitting the rotational motion to the foot part via the ankle part,
- the deceleration ratio rate is expressed by a following expression:
- K
-
- 2
-
- π
-
- N
-
- b
-
- R
- 2
-
- L
-
- b
-
- N
-
- m
- Nm is a number of teeth of a pulley on a side of motor in the transmission mechanism,
- Nb is a number of teeth of the pulley on a side of a ball screw in the transmission mechanism, Lb is a lead length of the ball screw,
- R is a arm length of the ankle part, and
- K is a deceleration coefficient by the crank represented as follows:
- K
- =
- Sin
-
- (
- α
- +
- β
- )
- Cos
-
- β
- wherein α is an angle between an arm of the ankle part and a vertical direction, and
- β is an angle between the vertical direction and the rod.
A control method of an assistance device to assist a joint motion of a lower limb, wherein
- the assistance device comprises:
- a driving part which comprises a motor and a transmission mechanism to change a speed of the motor, and converts a rotational motion of the motor into a linear motion;
- an elastic part which alleviates an impact from an object through a foot part and accumulates an impact force by compression, and releases an accumulated energy by stretching to apply an energizing force for motion assistance;
- and
- a crank mechanism which is provided between the driving part and the foot part, and converts the linear motion into a rotational motion while changing a deceleration ratio, thereby transmitting the rotational motion to the foot part via an ankle part,
- the crank mechanism comprises a crank connected to and rotatable around the rotation shaft of the ankle part, and a rod with one end and the other end, the one end of the rod being connected to a leading end of the driving part, the other end of the rod being connected to the crank,
- the deceleration ratio rate is expressed by a following expression:
- K
-
- 2
-
- π
-
- N
-
- b
-
- R
- 2
-
- L
-
- b
-
- N
-
- m
- Nm is a number of teeth of a pulley on a side of motor in the transmission mechanism,
- Nb is a number of teeth of the pulley on a side of a ball screw in the transmission mechanism, Lb is a lead length of the ball screw,
- R is a arm length of the ankle part, and
- K is a deceleration coefficient by the crank represented as follows:
- K
- =
- Sin
-
- (
- α
- +
- β
- )
- Cos
-
- β
- wherein “α” is an angle between an arm of the movable part and a vertical direction, and “β” is an angle between the vertical direction and the rod,
- and wherein:
- walking can be assisted by accumulating and releasing energy by the elastic part in addition to adjusting torque of the motor by estimating moving situation of a user within a walking cycle and controlling the driving part according to an estimated moving situation.
Dependencies are inferred from the claim text.