Robot Path Interpolation With Endpoint Speed and Acceleration Limits
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Solution Overview
Problem
Existing robot path generation methods face challenges in accurately controlling robot motion due to issues such as insufficient speed at end points, inability to reach target positions, and exceeding acceleration limits, particularly in high-order interpolation methods like quintic spline interpolation and simple linear interpolation.
Innovation Solution
A path generation method that includes linear interpolation between target positions, with corrections to ensure path acceleration does not exceed predefined limits and initial speeds meet or exceed minimum required speeds to reach subsequent target positions, using a two-tiered control system with a superior and subordinate control device to manage robot commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If linear interpolation is used for path generation, then the path control is simple and easy to implement, but the speed at end points becomes insufficient and the robot cannot reach target positions
Solution Approach 1:
The patent applies preliminary action by calculating and setting the initial speed at the start point of each interpolation zone in advance, before the robot actually traverses the zone. This pre-calculated initial speed ensures that the robot maintains sufficient velocity throughout the interpolation zone and reaches the end point with adequate speed, preventing the speed insufficiency problem that occurs with simple linear interpolation.
2Stability of the object's composition
If high-order interpolation such as quintic spline interpolation is used, then the path smoothness is improved, but the acceleration exceeds the acceleration limit and the motion control becomes complex
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the initial speed parameter and the number of interpolation zones based on the robot's acceleration limits and the required path smoothness. Instead of using fixed high-order interpolation that may exceed acceleration limits, the system modifies these parameters to ensure that acceleration remains within acceptable bounds while still achieving smooth path traversal.
Solution Approach 2:
The patent applies segmentation by dividing the entire path into multiple interpolation zones, where each zone has its own initial speed and acceleration constraints. This segmentation allows the system to manage acceleration locally within each zone, preventing any single zone from exceeding the maximum acceleration limit while collectively achieving smooth overall path traversal.
3Manufacturing precision
If the number of interpolation zones is increased, then the path control precision is improved, but the control period becomes longer and the system responsiveness decreases
Solution Approach 1:
The patent applies dynamics by making the number of interpolation zones and the control period adaptive rather than fixed. The system dynamically adjusts these parameters based on the robot's current state, the path characteristics, and the acceleration limits. This allows the system to increase precision when needed while maintaining faster response times when the path allows, optimizing the trade-off between precision and responsiveness.
Data Source
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AI summary
A method of the present disclosure is a path generation method of generating a path of a robot using a command from an external apparatus, including (a) sequentially receiving command information including a control command from the external apparatus, and (b) determining a path position with interpolation between a first target position and a second target position. The step (b) includes (b1) obtaining the path position by performing linear interpolation between the first target position and the second target position, (b2) determining whether or not path speed at the second target position is no lower than lower limit speed, and (b3) correcting the path speed between the first target position and the second target position so as to become no lower than the lower limit speed when it is determined that the path speed at the second target position fails to be no lower than the lower limit speed.