Industrial Robot Trajectory Planning Under Jerk and Torque Limits
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Solution Overview
Problem
Existing methods for determining time-optimal trajectories for industrial robots are inefficient due to suboptimal calculations and lack of consideration for dynamic limits, particularly in mixed path planning involving both continuous and point-to-point paths, leading to insufficient efficiency and longer travel times.
Innovation Solution
A method that calculates a time-optimal trajectory by dividing the path into partial paths, using 7-phase trajectories and polynomial profiles, and applying filters to ensure compliance with velocity, acceleration, and jerk limits, while also considering motor torque constraints, to determine joint angles over time intervals, thereby optimizing travel time and adhering to dynamic limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional online calculation methods are used to determine trajectories, then calculation speed is improved, but trajectory optimality deteriorates
Solution Approach 1:
The patent pre-calculates and stores optimal trajectories offline before actual robot operation. By performing the computationally intensive trajectory optimization in advance and storing the results in a database, the system achieves both optimality (from thorough offline calculation) and speed (from rapid online retrieval), resolving the contradiction between calculation completeness and execution speed.
2Ease of manufacture
If individual PTP and CP path methods are used separately, then calculation simplicity is improved, but overall path optimality deteriorates
Solution Approach 1:
The patent merges PTP (point-to-point) and CP (continuous path) planning methods into a unified trajectory optimization framework. The system can handle mixed paths containing both PTP and CP segments, automatically optimizing the entire path while considering dynamic limits and transition requirements, thereby achieving both calculation feasibility and path optimality.
3Ease of operation
If velocity and acceleration specifications are optimized, then mathematical convexity is improved, but dynamic limit compliance deteriorates
Solution Approach 1:
The patent extends the optimization parameters beyond velocity and acceleration to include jerk (rate of change of acceleration) and motor torque. By formulating the optimization problem in terms of joint angles, velocities, accelerations, and jerks while explicitly incorporating motor torque limits and dynamic constraints, the system maintains mathematical tractability while ensuring full compliance with dynamic limits through comprehensive parameter consideration.
Data Source
AI summary
A method, a device and a computer program product determines a time-optimal trajectory before the start of movement for a movement of an industrial robot, predefined by movement parameters, on a path. The method includes dividing the path into one or more partial paths and carrying out a predetermined number of repetitions of the following steps: calculating a time-optimal trajectory for each of the partial paths, joining the time-optimal trajectories for all partial paths, checking whether predetermined limit values are not exceeded and whether the fastest movement has been found, and varying one or more of the movement parameters.