Adaptive Lookup Table (1D Stair-Fit)

One-dimensional adaptive table lookup

Library

Simulink Design Optimization

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Description

The Adaptive Lookup Table (1D Stair-Fit) block creates a one-dimensional adaptive lookup table by dynamically updating the underlying lookup table. The block uses the outputs, y, of your system to do the adaptations.

Each indexing parameter u may take a value within a set of adapting data points, which are called breakpoints. Two breakpoints in each dimension define a cell. The set of all breakpoints in one of the dimensions defines a grid. In the one-dimensional case, each cell has two breakpoints, and the cell is a line segment.

You can use the Adaptive Lookup Table (1D Stair Fit) block to model time-varying systems with one input.

Data Type Support

Doubles only

Parameters

First input (row) breakpoint set

The vector of values containing possible block input values. The input vector must be monotonically increasing.

Make initial table an input

Selecting this check box forces the Adaptive Lookup Table (1D Stair-Fit) block to ignore the Table data (initial) parameter, and creates a new input port Tin. Use this port to input the table data.

Table data (initial)

The initial table output values. This vector must be of size N-1, where N is the number of breakpoints.

Table numbering data

Number values assigned to cells. This vector must be the same size as the table data vector, and each value must be unique.

Adaptation method

Select one of the following options:

• Sample mean — Average all the values received within a cell.

• Sample mean (with forgetting) — Give more weight to the new data. The weighting is determined by the Adaptation gain parameter.

For more information, see Selecting an Adaptation Method.

Adaptation gain (0 to 1)

A number between 0 and 1 that regulates the weight given to new data during the adaptation. A 0 means short memory (last data becomes the table value), and 1 means long memory (average all data received in a cell).

Make adapted table an output

Selecting this check box creates an additional output port Tout for the adapted table.

Add adaptation enable/disable/reset port

Selecting this check box creates an additional input port Enable that enables, disables, or resets the adaptive lookup table. A signal value of 0 applied to the port disables the adaptation, and signal value of 1 enables the adaptation. Setting the signal value to 2 resets the table values to the initial table data.

Add cell lock enable/disable port

Selecting this check box creates an additional input port Lock that provides the means for updating only specified cells during a simulation run. A signal value of 0 unlocks the specified cells and signal value of 1 locks the specified cells.

Action for out-of-range input

Ignore or Adapt by extrapolating beyond the extreme breakpoints.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2009a