1.3.1 Computer Control of Robot Paths (Incremental Interpolation)

 

• Path Planning is a simple process where the path planning methods described before (such as straight line motion) are used before the movement begins, and then a simple real-time lookup table is used.

 

• The path planner puts all of the values in a trajectory table

 

• The on-line path controller will look up values from the trajectory table at predetermined time, and use these as setpoints for the controller.

 

• The effect of the two tier structure is that the robot is always shooting for the next closest ‘knot-point’ along the path.

 

 

• The above scheme leads to errors between the planned, and actual path, and lurches occur when the new setpoints are updated for each servo motor.

 

 

 

 

• The quantization of the desired position requires a decision of what value to use, and this value is fixed for a finite time.

 

• The result is that the path will tend to look somewhat bumpy,