Overview

Description

The Actual Position block is an Input block that is a source for Actual Position (Feedback) data. The output from the Actual Position block is the updated Axis Actual Position value, as determined by the Evaluate Block.

The Actual Position block is commonly used to calculate position error, generate position based feedforwards, or inputs to lookup tables.

Example

The following example is using the Actual Position to generate a sliding filter, allowing the digital BiQuad to change based on the Actual Position of an axis.

The following parameters are used to configure this block at load time:

AxisNumber	The number of the axis which is the source of the position data. This number may be absolute or linked to the Model Number.
Evaluate Block	This block allows you to specify whether the block executes Every Sample, Every Other Sample (Odd or Even), or Every Fourth Sample (and specify the First, Second, Third, or Fourth) or background. This provides greater flexibility in controlling the execution of a model and to preserve performance for other areas of motion control.
User Defined Block Priority	When selected, allows you to enter a Priority Code to modify Execution Ordering of this block. For more information, see Block Execution Order and User Defined Block Priority.
Priority	For an explanation of how the Priority field is used by the MechaWare Model Downloader, see Block Execution Order and User Defined Block Priority.
User Data 0	Application-specific data. See User Data Storage.
User Data 1	Application-specific data. See User Data Storage.

Matlab/Simulink

Simulink Interface

simulink1

The sim (opt) input is an input which only relates to simulation.

Note: This input is only used when simulating within Simulink and is ignored when the model is downloaded to a controller.

By supplying a value from a Simulink source or a trajectory generator that passes the value through the model, will allow you to see how the system responds given an actual position. Additionally, allows you to generate a Position Error when compared to a simulated Command Position.

The Output of the Actual Position block is the Axis Actual Position value.

The Axis Number of the axis provides the position data that is determined by the Axis Number parameter. This number can be absolute or linked to the model number.

The block has two user data fields (User Data 0, User Data 1) to store application-specific data for convenient storage and retrieval. See User Data Storage for details.

The block's update schedule is determined by the Evaluate Block. The following Parameter Dialog Box can be opened by double-clicking on the block in a Simulink Model:

simulink2

Double-click on the Lookup Table block to open the Block Parameters window.

C++ API

Actual Position

Declaration

Public Method

class ACTUAL_POSITONBlock: public virtual Block
{
public:
	// User accessible coefficients
};

Required Header: mechaware.h

Description

The Actual Position block is used to connect the inputs of a model.

Methods

Block Methods

Overview

Overview

Matlab/Simulink

Simulink Interface

C++ API

Actual Position

See Also