CANopen DSP 402 Implementation Guide
92
12.3.1Linear Interpolation
Linear interpolation requires only the position specified in data record object 0x60C1. The structure of the position data is according to data type 0x41 (refer to the Elmo CANopen Implementation Guide). The velocity at each time point is calculated by finding the difference between the corresponding position and the position of the previous point, as in the following figure.
| P3 |
P1 | P2 |
P0
∆T | ∆T | ∆T | ∆T |
T start | Time |
|
|
Figure 10: Linear IP
In the linear interpolation, two set points can be given in one message and thereby save on busload and real time requirements.
12.3.2Spline Interpolation
In cubic spline interpolation, the user specifies both the position and the speed at each time point. The record data type is 0x44 (refer to the Elmo CANopen Implementation Guide). The drive constructs the motion path to be at the given time, at the given position, with the given speed, as in the following figure. Spline interpolation can yield a more accurate path specification with fewer time points, but it requires the care in constructing the speed data.
P3
P1P2
P0
∆T | ∆T | ∆T | ∆T |
T start | Time |
|
|
Figure 11: Spline IP
