Vehicle Trajectory Planning with Actuator-Limit Search Constraints
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Solution Overview
Problem
Current vehicle trajectory planning systems lack the ability to account for actuator limits and dynamics, leading to the planning of non-executable trajectories, controller windup, and increased computational effort.
Innovation Solution
A procedure for vehicle trajectory planning that includes creating an actuator model, determining time steps for foresight, limiting the search space based on actuator limits, and converting torque limits to vehicle acceleration limits, ensuring that only executable trajectories are planned.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the planner does not consider actuator limits and dynamics, then the planning process is simpler and faster, but the planned trajectories become non-executable and cause controller windup
Solution Approach 1:
The patent applies preliminary action by predicting actuator states (torque, acceleration) in advance for the entire forecast horizon before trajectory optimization begins. This pre-computed actuator information is then used to define realistic boundary conditions for the planner, ensuring trajectories are executable without requiring iterative adjustments during the planning process.
Solution Approach 2:
The patent introduces an intermediary actuator model that translates controller commands into predicted actuator states (torque, acceleration). This intermediary layer bridges the gap between the planner's abstract trajectory requirements and the physical actuator constraints, enabling the planner to work with realistic boundary conditions without directly managing complex actuator dynamics.
2Device complexity
If the planner uses a simple approach without actuator information, then the computational effort is reduced, but the trajectories planned are not feasible with available actuator dynamics
Solution Approach 1:
The patent applies preliminary action by pre-computing actuator states (torque, acceleration) for the entire forecast horizon before trajectory optimization. This pre-computed information enables the planner to use simple boundary conditions that already embody complex actuator dynamics, achieving high trajectory accuracy without increasing planner complexity.
Solution Approach 2:
The patent transforms the planning problem by changing parameters from direct torque/force specifications to acceleration-based boundary conditions derived from predicted actuator states. This parameter transformation allows the planner to maintain simplicity while achieving high accuracy, as the acceleration limits naturally encode the complex actuator dynamics without requiring the planner to understand them.
3Speed
If actuator limits are not predicted in advance, then the system response is faster, but frequent replanning occurs causing drift between required and actually driven trajectory
Solution Approach 1:
The patent applies preliminary action by predicting actuator states for the entire forecast horizon in advance, before trajectory optimization begins. This pre-computation eliminates the need for iterative replanning during execution, as the planner receives realistic boundary conditions upfront, ensuring trajectory feasibility without sacrificing response speed.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining consistent actuator state predictions across the entire forecast horizon. This continuous actuator information allows the planner to generate a single feasible trajectory that can be executed without interruption or replanning, eliminating drift between required and actual trajectories while maintaining fast response.
Data Source
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AI summary
The invention relates to a method for steering a vehicle (1) with at least one actuator along a trajectory, in which the trajectory is planned within a search range taking into account a projection of at least one manipulated variable of the actuator. Said method comprises the following steps: determining an actuator model of the actuator based on the at least one adjustment variable of the actuator; defining the time steps of the projection; determining the change in the adjustment variable of the actuator along the time steps based on the actuator model and a limit value of the adjustment variable; limiting the search range based on the limit value of the adjustment variable of the actuator; determining an acceleration value and/or a deceleration value of the vehicle (1) by converting the at least one adjustment variable with the vehicle mass and the wheel radius; and outputting the acceleration value and the deceleration value for limiting the search range within which the trajectory is planned,