Robot Trajectory Planning With Orientation-Based Acceleration Limits
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Solution Overview
Problem
Existing robot trajectory generation methods fail to fully utilize the robot's capability to move faster when the arm is contracted due to a common acceleration upper limit value applied in all orientations, leading to suboptimal performance.
Innovation Solution
A trajectory generation device that generates a trajectory exploration graph, acquires orientation-specific acceleration upper limit values, sets velocities and accelerations based on these values, and explores paths with minimum total cost to optimize movement speed across different orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a common acceleration upper limit value is applied in all orientations, then the control system is simple, but the robot cannot move the hand at the velocity that is originally possible when the arm is contracted
Solution Approach 1:
The patent applies dynamics by making the acceleration upper limit value variable based on robot orientation. Instead of using a fixed common value, the system dynamically adjusts the acceleration limit according to the current orientation angles (θ1, θ2, θ3) of the robot arm. This allows the robot to operate at higher acceleration values when the arm is contracted (where higher speeds are physically possible) and uses more conservative limits when extended, thereby maximizing productivity while respecting physical constraints.
Solution Approach 2:
The patent implements parameter changes by modifying the acceleration upper limit value based on orientation parameters. The system calculates different acceleration limits corresponding to different orientation states of the robot arm. By changing this critical parameter dynamically, the trajectory generation unit can optimize movement speed for each orientation, resolving the contradiction between maintaining simplicity and achieving maximum operational velocity.
2Productivity
If the orientations of the robot in the middle of the trajectory are not taken into consideration, then the calculation is simpler, but it is difficult to make full use of the capability of the robot
Solution Approach 1:
The patent applies segmentation by dividing the trajectory into discrete segments between waypoints. For each segment, the system calculates the orientation at intermediate points and determines appropriate acceleration limits. This segmentation approach allows the system to consider orientation changes throughout the trajectory without requiring continuous complex calculations, balancing computational efficiency with full capability utilization.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing multiple acceleration upper limit values corresponding to different orientation states before actual trajectory execution. The system prepares a lookup table or database of orientation-specific acceleration limits in advance, so during real-time operation, the trajectory generation unit can quickly retrieve and apply the appropriate values without performing complex real-time calculations, thus reducing computational time while maintaining high capability utilization.
Data Source
AI summary
A trajectory generation device which generates a trajectory of a robot includes: a trajectory exploration graph generation unit which is configured to generate a trajectory exploration graph composed of a plurality of nodes for generating the trajectory; an acceleration upper limit value acquisition unit which is configured to acquire a first acceleration upper limit value based on orientations and an acceleration direction of the robot at a current node; a velocity and acceleration setting unit which is configured to set a first velocity representing a velocity when moving from the current node to a next node adjacent to the current node based on the acquired first acceleration upper limit value, and an acceleration; and a node cost calculation unit which is configured to calculate a moving time by using the set first velocity and the acceleration as cost from the current node to the next node.