# US 10,865,075 B2 · Dynamic optimization of a crane load curve

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- Number: US 10,865,075 B2
- Document ID: US10865075B2
- Status: Granted
- Kind: B2
- Application number: 16/138,205
- Filed: 2018-09-21
- Published: 2019-03-21
- Granted: 2020-12-15
- Earliest claimed: 2017-09-21
- Assignees: Manitowoc Crane Group France SAS
- Applicants: Manitowoc Crane Group France
- Inventors: Xavier Claeys
- Web page: https://patentgrep.com/patent/US10865075B2

## CPC

- B66C 13/48: Automatic control of crane drives for producing a single or repeated working cycle; Program control
- B66C 13/063: {electrical}
- B66C 13/22: for electric drives (transmitting control pulses B66C13/40; systems or devices of general application H02P)
- B66C 23/90: Devices for indicating or limiting lifting moment
- B66C 2700/08: Electrical assemblies or electrical control devices for cranes, winches, capstans or electrical hoists
- 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 method for controlling command of lifting a load suspended from a boom, carried by a mast of a crane, includes determining: depending on the mass of the suspended load, a specified load factor quantifying an acceptable exceedance with respect to a predetermined maximum allowable load for said crane; a maximum permitted lifting acceleration, depending on the mass of the suspended load, on the specified load factor and on the distribution position of the load suspended on the boom with respect to the mast; from lifting speed setpoints, optimized lifting speed setpoints intended to be executed by a motor device for displacing the suspended load according to a lifting movement so that the acceleration related to the lifting movement remains, in absolute value, less than or equal to the maximum permitted acceleration.

## Claims

### Claim 1

A method for controlling the command of the lifting of a load suspended from a boom, carried by a mast of a crane, the method including:
determining, depending on a mass (M) of the suspended load, a specified load factor (ψ0*) quantifying an acceptable exceedance related to a predetermined maximum allowable load for said crane;
determining a maximum permitted lifting acceleration (L″MAX), depending on the mass (M) of the suspended load, the specified load factor (ψ0*) and a distribution position (Xc) of the load suspended on the boom with respect to the mast;
determining, from lifting speed setpoints (CMD), optimized lifting speed setpoints (CMD′) to be executed by a motor device for displacing the suspended load according to a lifting movement so that an acceleration related to the lifting movement remains, in absolute value, less than or equal to the maximum permitted acceleration (L″MAX).

### Claim 2 (depends on 1)

The method according to claim 1, wherein the maximum permitted lifting acceleration (L″MAX) is determined using the following mathematical expression:
ℊ
⁢
⁢
J
z
x
c
2
⁢
M
+
J
z
⁢
ψ
0
*
wherein:
xc, corresponds to the distribution position of the suspended load;
M corresponds to the mass of the suspended load; and
Jz corresponds to a model of stiffness and inertia of the first order related to the structure of the crane.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the specified load factor (ψ0*) is determined from a maximum allowable load curve, corresponding to a limit load factor (ψ0) and to a maximum static load.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the limit load factor (ψ0) is determined from a first theoretical threshold dependent on theoretical load capacities handled by the crane and from a second threshold dependent on measurement uncertainties related to the mass of the suspended load and/or to the lifting movement of the suspended load.

### Claim 5 (depends on 3)

The method according to claim 3, wherein the specified load factor (ψ0*) is obtained by multiplying the limit load factor (ψ0) by a ratio between the maximum static load corresponding to the maximum allowable load curve and the mass (M) of the suspended load.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the optimized lifting speed setpoints (CMD′) are determined so that their execution by the motor device for displacing the suspended load according to the lifting movement meets the following condition:
the lifting acceleration of the suspended load, in absolute value, remains less than or equal to the maximum permitted acceleration (L″MAX); and
one or more of the following additional conditions:
the lifting speed of the suspended load, in absolute value, remains lower than a maximum permitted lifting speed (VMAX BRK), the maximum permitted lifting speed (VMAX BRK) being determined depending on the capacities of the crane to slow down the movements of the suspended load; and/or
the lifting speed of the suspended load, in absolute value, remains lower than a maximum safety lifting speed (VMAX SEC), determined depending on the capacities of the crane to withstand a sudden lying of the suspended load on the ground and/or an emergency stopping; and/or
the lifting acceleration of the suspended load, in absolute value, remains lower than a maximum lifting acceleration (L″SEC) achievable by the motor device; and/or
the lifting acceleration of the suspended load, in absolute value, remains greater than a minimal lifting acceleration (L″MIN).

### Claim 7 (depends on 1)

The method according to claim 1, wherein the optimized lifting speed setpoints are determined so that the absolute value of the lifting speed of the suspended load increases, over a predefined period of time, along a ramp having a slope corresponding to the maximum permitted lifting acceleration (L″MAX).

### Claim 8 (depends on 1)

A computer program including instructions for performing the steps of the method according to claim 1, when said program is executed by a processor.

### Claim 9 (depends on 1)

A computer-readable recording medium on which is recorded a computer program comprising instructions for performing the steps of the methods according to claim 1.

### Claim 10 (depends on 1)

The method according to claim 1, further comprising:
controlling operation of the motor device based on the optimized lifting speed setpoints (CMD′).

### Claim 11

A tower crane including a mast supporting a boom on which is mounted a carriage intended to carry a suspended load, the tower crane further comprising a system for controlling the command of the lifting of the suspended load, the system configured to:
determine, depending on the mass (M) of the suspended load, a specified load factor (ψ0*) quantifying an acceptable exceedance with respect to a predetermined maximum allowable load for said crane;
determine a maximum permitted lifting acceleration (L″MAX), depending on the mass (M) of the suspended load, on the specified load factor (ψ0*) and on the distribution position (Xc) of the load suspended on the boom with respect to the mast;
determine, from lifting speed setpoints (CMD), optimized lifting speed setpoints (CMD′) intended to be executed by a motor device (41) for displacing the suspended load according to a lifting movement so that the acceleration related to the lifting movement remains, in absolute value, less than or equal to the maximum permitted acceleration (L″MAX).

### Claim 12 (depends on 11)

The tower crane of claim 11, wherein the system is further configured to control operation of the motor device based on the optimized lifting speed setpoints (CMD′).