Robot Trajectory Planning With Joint-Axis Grouping for Direction Constraints
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Solution Overview
Problem
Existing trajectory planning methods for multi-axis robots are limited in determining the direction of the robot arm's tip and cannot effectively plan a trajectory while satisfying direction restrictions, leading to potential interference with obstacles.
Innovation Solution
A trajectory planning apparatus that classifies joint axes into different groups, including a path search axis group, to minimize an evaluation function and calculate angles for each axis group, ensuring the robot arm's direction constraint is met during path planning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If joint interpolation path constraining is applied to joints J4-J6, then the robot posture is limited and interference with obstacles is avoided, but the direction of the robot arm tip cannot be properly controlled and trajectory planning fails to satisfy direction restrictions
Solution Approach 1:
The patent segments the six joint axes into two independent groups: J1-J3 (first group) and J4-J6 (second group). Each group is planned independently with its own configuration space search, allowing the direction control requirements to be applied to one group while maintaining obstacle avoidance capabilities in the other group through joint interpolation constraints.
Solution Approach 2:
The patent introduces a new dimension of control by performing trajectory planning in two separate configuration spaces simultaneously. The first configuration space (J1-J3) handles position and direction requirements, while the second configuration space (J4-J6) handles obstacle avoidance through joint interpolation, effectively adding a dimensional layer to the trajectory planning problem.
2Adaptability or versatility
If only joints J1-J3 are searched in configuration space, then direction restrictions can be satisfied, but interference with obstacles cannot be avoided
Solution Approach 1:
The patent divides the joint axes into two groups (J1-J3 and J4-J6) that can be planned independently. By segmenting the control problem, the system can satisfy direction restrictions through configuration space search on J1-J3 while simultaneously ensuring obstacle avoidance through joint interpolation constraints on J4-J6.
Solution Approach 2:
The patent merges two independent trajectory planning processes into a unified system. The first process searches configuration space for J1-J3 to satisfy direction restrictions, while the second process applies joint interpolation constraints on J4-J6 for obstacle avoidance. Both processes are combined to produce a complete trajectory that satisfies all requirements.
3Device complexity
If joint paths are determined in advance without considering all joint axes, then computation is simplified, but the robot arm tip direction cannot be assumed and trajectory planning fails
Solution Approach 1:
The patent segments the trajectory planning computation into two independent parts: configuration space search for J1-J3 and joint interpolation for J4-J6. This segmentation reduces the overall computational complexity compared to searching all six joints simultaneously, while still enabling complete trajectory planning that satisfies both direction restrictions and obstacle avoidance requirements.
Data Source
AI summary
A trajectory planning apparatus including a joint axis classification unit for classifying a plurality of joint axes of a robot into axis groups, according to joint axis classification information for classifying into the axis groups including at least a path search axis group, a path search unit for searching for a path of an angle of the joint axis classified into the path search axis group that minimizes an evaluation function for evaluating a planed trajectory, based on trajectory start point information representing a posture of the robot at a start point of the planed trajectory and trajectory endpoint information representing a posture of the robot at an end point of the planned trajectory, and an axis group angle calculation unit for calculating an angle of the joint axis classified into each axis group other than the path search axis group during the search of the path.