# US 2021/0276838 A1 · Crane and crane control method

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- Number: US 2021/0276838 A1
- Document ID: US20210276838A1
- Status: Published application
- Kind: A1
- Application number: 17/256,520
- Filed: 2019-07-04
- Published: 2021-09-09
- Earliest claimed: 2018-07-09
- Assignees: Tadano Ltd.
- Applicants: Tadano Ltd.
- Inventors: Yoshimasa MINAMI
- Web page: https://patentgrep.com/patent/US20210276838A1

## CPC

- B66C 13/105: {electrical}
- B66C 23/88: Safety gear (for cranes in general B66C15/00; for rope, cable, or chain winding mechanisms B66D1/54)
- B66C 13/22: for electric drives (transmitting control pulses B66C13/40; systems or devices of general application H02P)
- B66C 13/42: Hydraulic transmitters
- B66C 13/46: Position indicators for suspended loads or for crane elements
- B66C 13/48: Automatic control of crane drives for producing a single or repeated working cycle; Program control
- B66C 2700/088: Remote control of electric cranes
- B66C: CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES ({specially adapted for lifting invalids A61G7/10;} rope, cable, or chain winding mechanisms, braking or detent devices therefor B66D; specially adapted for nuclear reactors G21)

## Abstract

A crane is provided. The crane includes an acceleration sensor that detects the acceleration of a load, wherein a target velocity signal is converted into target location coordinates of the load, current location coordinates of a boom are calculated from a slewing angle, a luffing angle, and an expansion/contraction length, the spring constant of a wire rope is calculated from the previously calculated location of the load from a unit time earlier, the current location coordinates of the boom, and the current accelerations of the load as detected by the acceleration sensor, target location coordinates of the boom are calculated from the accelerations, the spring constant, and the target location coordinates of the load, and an actuator operation signal is generated.

## Claims

### Claim 1

A crane comprising:
control circuitry configured to control an actuator of a boom based on a target speed signal relating to a moving direction and a speed of a load suspended from the boom by a wire rope and a suspending tool; and
an acceleration sensor configured to detect an acceleration of the suspending tool or the load, wherein
the control circuitry is configured to:
convert, every predetermined unit time, the target speed signal into a target position of the load relative to a reference position,
compute, every unit time, a spring constant of the wire rope from a previously-computed position of the load the unit time before, the current position of the boom tip relative to the reference position and a current acceleration of the suspending tool or the load,
compute, every unit time, a target position of the boom tip for the target position of the load from the current acceleration of the suspending tool or the load, the spring constant of the wire rope and the target position of the load, and
generate, every unit time, an operation signal for the actuator based on the target position of the boom tip.

### Claim 2 (depends on 1)

The crane according to claim 1, wherein a relationship between the target position of the boom tip and the target position of the load is expressed by Expression 1 based on an acceleration of the load, a weight of the load, the spring constant of the wire rope and the target position of the load,
the control circuitry is configured to:
compute, every unit time, the spring constant of the wire rope from the previously-computed position of the load the predetermined unit time before, the current position of the boom tip and the current acceleration of the suspending tool or the load using Expression 1, and
compute, every unit time, the target position of the boom tip for the target position of the load from the current acceleration of the suspending tool or the load, the spring constant of the wire rope and the target position of the load using Expression 1:
m{umlaut over (p)}=mg+f=mg+kf(q−p) (1)
where f is a tension of the wire rope, kf is the spring constant, m is a mass of the load, q is the current position or the target position of the tip of the boom, p is the current position or the target position of the load and g is a gravitational acceleration.

### Claim 3

A crane controlling method performed by control circuitry for controlling an actuator of a boom based on a target speed signal relating to a moving direction and a speed of a load suspended from the boom by a wire rope and a suspending tool, the method comprising:
converting, every predetermined unit time, the target speed signal into a target position of the load relative to a reference position;
obtaining, every unit time, a current acceleration of the suspending tool or the load;
computing, every unit time, a spring constant of the wire rope from a previously-computed position of the load the unit time before, a current position of a boom tip relative to the reference position and the current acceleration of the suspending tool or the load;
computing, every unit time, a target position of the boom tip for the target position of the load from the current acceleration of the suspending tool or the load, the spring constant of the wire rope and the target position of the load; and
generating, every unit time, an operation signal for the actuator based on the target position of the boom tip.