Concrete Pump Articulated Arm Trajectory Control Under Hydraulic Constraints

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Solution Overview

Problem

The control of the distribution mast in concrete pumps is complex, requiring coordination of multiple rotary degrees of freedom in a three-dimensional workspace, with a high risk of uncontrolled movement of the final hose, endangering construction site staff.

Innovation Solution

A joint arm control system that includes geometry control, which generates a trajectory with target values for the movement of the rotary sector and/or joints from input values for a target TCP movement, by solving an optimization problem that minimizes the deviation between the target TCP movement and the TCP movement resulting from the trajectory in a physical model of the joint arm, while considering restrictions on hydraulics and workspace.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If single-axis control is used for the distribution mast, then the control system is simpler, but the risk of uncontrolled movement increases and safety deteriorates

Engineering Contradiction:
Improvecontrol system complexityVSAvoidsafety
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The control system continuously receives feedback from sensors about the actual position and movement of the distribution mast, comparing it with the planned trajectory. This closed-loop control enables real-time corrections to prevent uncontrolled movements while maintaining manageable system complexity through automated monitoring and adjustment mechanisms.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system dynamically adjusts control parameters and trajectory planning based on real-time system state and external conditions. This dynamic adaptation allows the system to maintain safety under varying operational conditions without requiring overly complex static control structures, balancing simplicity and reliability.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If multiple rotational degrees of freedom are coordinated in three-dimensional workspace, then positioning precision improves, but control complexity increases

Engineering Contradiction:
Improvepositioning precisionVSAvoidcontrol complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The control system introduces intermediate computational layers including trajectory planning modules and coordinate transformation mechanisms that mediate between simple operator inputs and complex multi-axis actuator coordination. This intermediary processing achieves precise three-dimensional positioning while shielding the operator from the underlying control complexity through automated kinematic calculations and path optimization.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If optimization problem solving is used for trajectory generation, then movement accuracy improves, but computational requirements increase

Engineering Contradiction:
Improvemovement accuracyVSAvoidcomputational power
Core Design Contradiction:
Measurement precisionVSPower

Solution Approach 1:

The control system performs preliminary computation of optimal trajectories using optimization algorithms before execution, storing pre-calculated path data. This advance computation achieves high movement accuracy by solving complex optimization problems offline or in advance, reducing real-time computational requirements during actual arm movement while maintaining precision through pre-planned optimal paths.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3705663B2Articulated arm control for a concrete pump
Publication Date: 2025.04.16 LIEBHERR MISCHTECHN
  • EP3705663B2 patent drawingFigure 1
  • EP3705663B2 patent drawingFigure 2
  • EP3705663B2 patent drawingFigure 3

AI summary

The present invention relates to an articulated arm control system for the articulated arm of a concrete pump, wherein the articulated arm has a swivel base rotatable about a vertical axis and at least two segments pivotable about horizontal axes by means of joints, wherein the swivel base can be moved about the vertical axis via an actuator and the segments can be pivoted about the horizontal axes via actuators, wherein sensors are preferably provided for determining the rotation angle of the swivel base and for determining the joint angles of the joints, wherein the articulated arm control system serves to control the actuators and comprises a geometry control system which generates a trajectory with target values ​​for the movement of the swivel base and/or the joints from input values ​​for a target TCP movement.The geometry control is designed to determine the trajectory by solving an optimization problem, where the optimization problem, as the objective function, minimizes a deviation between the target TCP movement and a TCP movement resulting from the trajectory in a physical model of the articulated arm, with constraints of the hydraulics and/or the workspace being incorporated into the optimization as a constraint.