# US 2016/0355256 A1 · Aircraft landing gear longitudinal force control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0355256 A1 - Document ID: US20160355256A1 - Status: Published application - Kind: A1 - Application number: 14/443,282 - Filed: 2013-11-15 - Published: 2016-12-08 - Earliest claimed: 2012-11-16 - Assignees: Airbus Operations GmbH - Applicants: Airbus Operations Limited; Airbus Operations SAS - Inventors: Miguel Angel GAMA-VALDEZ; Louis-Emmanuel ROMANA; Andrea DAMIANI - Web page: https://patentgrep.com/patent/US20160355256A1 ## CPC - B64C 25/405: {Powered wheels, e.g. for taxing} - B60T 8/1703: {for aircrafts} - B60T 8/1766: Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle - B64C 25/426: {Braking devices providing an automatic sequence of braking} - Y02T 50/80: Energy efficient operational measures, e.g. ground operations or mission management - B64C: AEROPLANES; HELICOPTERS - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An aircraft landing gear longitudinal force control system for an aircraft having landing gears with braking and/or driving wheel(s). The system includes an error-based force controller having feedback for minimising any error between the demanded force and the actual force achieved by the force control system. The feedback may be derived from force sensors on the landing gear for direct measurement of the landing gear longitudinal force. The force control system may include an aircraft level landing gear total force controller and/or a landing gear level force controller for each actuated landing gear. ## Claims ### Claim 1 A landing gear force control system for an aircraft having a longitudinal axis and a plurality of landing gears having one or more braking and/or driving wheels, the force control system comprising an error-based force control module adapted to: receive an input signal representative of a longitudinal force demand to be achieved by the force control system; receive an input signal representative of an actual measured longitudinal force acting upon one or more landing gears; calculate any error between the force demand signal and the actual force signal; and output a longitudinal force command for the one or more landing gears so as to minimize any error between the demanded force and the actual force. ### Claim 2 (depends on 1) The force control system according to claim 1, wherein the error-based force control module is further adapted to: estimate the longitudinal force being achieved by the force control system based upon the longitudinal force command and known characteristics of the landing gear braking and/or driving wheel systems; and augment, or replace, the actual measured longitudinal force with the estimated longitudinal force for use in the error calculation. ### Claim 3 (depends on 2) The force control system according to claim 2, wherein the error calculation based upon the actual measured longitudinal force is amplitude limited. ### Claim 4 (depends on 1) The force control system according to claim 1, wherein the error-based force control module includes a landing gear total force controller associated with all of the landing gears of the aircraft and being configured to: receive an input signal representative of a landing gear total longitudinal force demand to be achieved by the force control system; receive an input signal representative of an actual measured longitudinal force acting upon all of the landing gears; calculate any error between the force demand signal and the actual force signal; and output a landing gear total longitudinal force command to be achieved by the force control system so as to minimize any error between the demanded force and the actual force. ### Claim 5 (depends on 4) The force control system according to claim 4, wherein the error-based force control module includes a summation block configured to receive an input signal representative of an actual measured longitudinal force acting upon each of the landing gears, and to output a signal to the total force controller representative of an actual measured longitudinal force being achieved for all of the landing gears. ### Claim 6 (depends on 1) The force control system according to claim 1, wherein the error-based force control module includes one or more landing gear force controllers each associated with a respective one of the landing gears equipped with braking and/or driving wheel(s), each landing gear force controller being configured to: receive an input signal representative of a landing gear longitudinal force demand to be achieved by the force control system for that landing gear; receive an input signal representative of an actual measured landing gear longitudinal force being achieved by the force control system for that landing gear; calculate any error between the force demand signal and the actual force signal; and output a landing gear longitudinal force command for that landing gear so as to minimize any error between the demanded force and the actual force. ### Claim 7 (depends on 6) The force control system according to claim 6, wherein each landing gear force controller is further adapted to limit the landing gear longitudinal force demand for its landing gear to within safe structural limits, so as to provide loads limitation for that landing gear. ### Claim 8 (depends on 6) The force control system according to claim 6, wherein each landing gear force controller includes an actuator gain estimator for its landing gear, and wherein the force controller output based upon the actual measured longitudinal force is limited based upon the estimated actuator gain. ### Claim 9 (depends on 1) The force control system according to claim 1, wherein the force control module further comprises a force distributor for dividing a total longitudinal force demand to be achieved by the force control system into a plurality of force components to be achieved by the respective landing gears equipped with braking and/or driving wheels. ### Claim 10 (depends on 1) The force control system according to claim 1, further comprising a configuration manager for providing configuration data to the force control module. ### Claim 11 (depends on 10) The force control system according to claim 10, wherein the configuration manager is arranged to receive one or more signals from effectors and/or sensors, and the configuration manager is adapted to generate the configuration data based upon the signals from the effector(s) and/or sensor(s). ### Claim 12 (depends on 10) The force control system according to claim 10, wherein the configuration manager is arranged to receive one or more signals representative of operational scenario(s) and/or parameter(s) of the aircraft, and the configuration manager is adapted to generate the configuration data based upon the aircraft parameter(s) and/or operational scenario(s). ### Claim 13 (depends on 10) The force control system according to claim 10, wherein the configuration manager is arranged to provide the configuration data to the force control module so as to reconfigure the force control module without disrupting its continuous operation. ### Claim 14 (depends on 10) The force control system according to claim 10, further comprising a fitness evaluation module for evaluating the fitness and/or reliability of one or more signals destined for the configuration manager, and outputting status data for the signal(s) to the configuration manager. ### Claim 15 (depends on 1) An aircraft having a longitudinal axis and a plurality of landing gears having one or more braking and/or driving wheels, and the force control system recited in claim 1. ### Claim 16 (depends on 15) The aircraft according to claim 15, wherein each landing gear includes at least one sensor for measuring force in the aircraft longitudinal direction acting upon the landing gear. ### Claim 17 A method for directly controlling force produced by one or more aircraft landing gears equipped with braking and/or driving wheels, the method comprising: receiving an input signal representative of a longitudinal force demand to be achieved by one or more landing gears; measuring force in the aircraft longitudinal direction acting upon one or more landing gears; calculating any error between the demanded force and the actual force; and outputting a corrected longitudinal force command for the one or more landing gears so as to minimize any error between the demanded force and the actual force. ### Claim 18 (depends on 17) The method according to claim 17, further comprising estimating the longitudinal force based upon the longitudinal force command and known characteristics of the landing gear braking and/or driving wheel systems; and augmenting, or replacing, the actual measured longitudinal force with the estimated longitudinal force for use in the error calculation. ### Claim 19 (depends on 17) The method according to claim 17, further comprising: receiving an input signal representative of a total longitudinal force demand to be achieved by all of the aircraft landing gears; receiving an input signal representative of an actual measured longitudinal force being achieved by all of the aircraft landing gears; calculating any error between the force demand signal and the actual force signal; and outputting a corrected total longitudinal force command so as to minimise any error between the demanded force and the actual force. ### Claim 20 (depends on 17) The method according to claim 17, further comprising, for each landing gear equipped with braking and/or driving wheels: receiving an input signal representative of a landing gear longitudinal force demand to be achieved by that landing gear; receiving an input signal representative of an actual measured landing gear longitudinal force being achieved by that landing gear; calculating any error between the force demand signal and the actual force signal; and outputting a corrected landing gear longitudinal force command for that landing gear so as to minimize any error between the demanded force and the actual force. ### Claim 21 (depends on 20) The method according to claim 20, further comprising limiting the landing gear longitudinal force demand for its landing gear to within safe structural limits, so as to provide loads limitation for that landing gear. ### Claim 22 (depends on 17) The method according to claim 17, further comprising distributing a total longitudinal force demand into a plurality of force components to be achieved by the respective landing gears equipped with braking and/or driving wheels. ### Claim 23 (depends on 22) The method according to claim 22, wherein the longitudinal force distribution minimizes undesired yaw moments by balancing the longitudinal forces either side of the aircraft centerline. ### Claim 24 (depends on 17) The method according to claims 17, further comprising reconfiguring the longitudinal force control without disrupting its continuous operation. ### Claim 25 (depends on 24) The method according to claim 24, wherein the reconfiguring is to account for a change of status of one or more effector(s) and/or sensor(s) and/or operational scenario(s) and/or parameter(s) of the aircraft.