Actuator Reference Trajectory Smoothing Under Velocity and Acceleration Limits
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Solution Overview
Problem
Humanoid robots often receive unfeasible joint trajectories that violate maximum velocity, acceleration, or jerk limits, leading to poor performance and potential damage, as existing systems fail to ensure smooth and feasible motion profiles for their actuators.
Innovation Solution
The proposed method generates a feasible smooth reference trajectory with at least third derivative continuity, constrained by maximum velocity and acceleration, using a trajectory preprocessor that enforces these limits by sampling and smoothing the original trajectory signal, and outputs this to the actuator controller to ensure safe and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unfeasible joint trajectories are generated from robot operation, then the robot can achieve desired spatial pose and movement, but the trajectories violate actuator capabilities causing poor performance and potential damage
Solution Approach 1:
The trajectory preprocessor performs preliminary smoothing and constraint enforcement on joint trajectories before they are executed by the actuators. By pre-processing the trajectories to ensure they meet velocity, acceleration, and jerk constraints, the system prevents actuator damage and poor performance while maintaining task completion capability.
Solution Approach 2:
The trajectory preprocessor acts as an intermediary component between the motion planning system and the actuator controllers. It receives raw joint trajectories, applies smoothing filters and constraint enforcement, and outputs feasible trajectories that satisfy both task requirements and actuator capabilities.
2Ease of operation
If smooth reference trajectories with third derivative continuity are generated, then velocity, acceleration, and jerk are bounded within actuator limits, but additional processing blocks and complexity are introduced
Solution Approach 1:
The trajectory preprocessor is divided into four distinct processing blocks, each responsible for a specific function: velocity constraint enforcement, trajectory smoothing, constraint verification, and output generation. This segmentation allows each block to be optimized independently while maintaining overall system manageability and clarity.
3Object-affected harmful factors
If maximum velocity and acceleration constraints are enforced on trajectory samples, then actuator safety is ensured, but the trajectory may require adjustment and delay
Solution Approach 1:
The trajectory preprocessor applies partial smoothing and constraint enforcement only where needed in the trajectory, rather than uniformly processing the entire trajectory. This allows the system to enforce safety constraints while minimizing unnecessary delays and maintaining trajectory fidelity in regions where constraints are already satisfied.
Data Source
AI summary
A method of controlling an actuator having a maximum velocity and a maximum acceleration includes accessing a reference trajectory signal comprising temporally-spaced reference positions for the actuator and accessing a trajectory template having at least a third derivative continuity and at least one characteristic constrained by the maximum velocity and the maximum acceleration. The method includes generating a smooth reference trajectory signal based on the reference trajectory signal and the trajectory template and outputting the smooth reference trajectory signal. Controls for the actuator can be generated based on the smooth reference trajectory signal.