A465 World Coordinates to Joint Angles

Converts cartesian world coordinates to joint angles for the CRS A465 robot.

Library

Description

The A465 World Coordinates to Joint Angles block computes the joint angles that place the robot end-effector at the given position and orientation for the CRS A465 robot. Since this mapping is not unique, additional information must be supplied to indicate which of the eight possible solutions (in general) is desired. The block uses the previous joint angles and the desired stance to arrive at a suitable configuration. If there is no solution because a joint is out of range, or the given stance cannot achieve the requested wrench, or the world coordinates are out of the robot workspace, then the error output will be non-zero to indicate the error. Typically, the stance supplied by the A465 Forward Kinematics block is used for the stance input.

Note that the A465 Inverse Kinematics block block is generally easier to use because it keeps track of the previous joint angles automatically. The reference frame is shown below:

Input Ports

World Coordinates

A 6-vector containing the position and orientation of the robot end-effector. The vector elements represent the X, Y, and Z cartesian coordinates of the end-effector in millimeters, followed by the yaw, pitch, and roll, respectively, in radians. Note that yaw is the rotation about the Z-axis, pitch is the rotation about the Y-axis and roll is the rotation about the X-axis.

Stance

A 3-vector representing the desired stance of the robot. The elements and their possible values are defined in the table below:

Previous Joint Angles

The previous joint angles (in radians) for the six A465 joints. The joint angles should be supplied as a 6-vector in order of the joints, i.e., base, shoulder, elbow, forearm roll, wrist pitch and wrist roll.

Output Ports

Joint Angles

The joint angles (in radians) for the six A465 joints. The joint angles should be supplied as a 6-vector in order of the joints, i.e., base, shoulder, elbow, forearm roll, wrist pitch and wrist roll.

Error

A vector denoting whether a solution could be found. The first element of the vector is an error code. An error code of zero indicates that a solution was found. The possible error codes and their meaning are listed in the table below. The second element is a joint number indicating which joint is out of range if the error is an "out of range" error. A joint number of 1 indicates the base joint, 2 denotes the shoulder joint, 3 is the elbow joint, 4 is the forearm roll joint, 5 is the wrist pitch joint and 6 is the wrist roll joint. If no error occurred then the joint number element is zero.

Data Type Support

This block supports inputs and outputs of type double.

Parameters and Dialog Box

The A465 World Coordinates to Joint Angles block has no parameters.

Targets

See Also

• Robots - CRS A465

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