Gravity Torque

R2026b

Joint torques that compensate gravity

• 

Gravity Torque block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Robotics System Toolbox / Manipulator Algorithms

Description

The Gravity Torque block returns the joint torques required to hold the robot at a given configuration with the current Gravity setting on the Rigid body tree robot model.

Examples

Calculate Manipulator Gravity Dynamics in Simulink

Use the manipulator algorithm blocks to compute and compare dynamics due to gravity for a manipulator robot.

• Open Script

Ports

Input

Config — Robot configuration

vector

Robot configuration, specified as a vector of positions for all nonfixed joints in the robot model, as set by the Rigid body tree parameter. You can also generate this vector for a complex robot using the homeConfiguration or randomConfiguration functions inside a Constant or MATLAB Function block.

Output

JointTorq — Joint torques

vector

Joint torques, specified as a vector. Each element corresponds to a torque applied to a specific joint. The number of joint torques is equal to the degrees of freedom (number of nonfixed joints) of the robot.

Parameters

Rigid body tree — Robot model

twoJointRigidBodyTree (default) | RigidBodyTree object

Robot model, specified as a rigidBodyTree object. You can also import a robot model from an URDF (Unified Robot Description Formation) file using importrobot.

The default robot model, twoJointRigidBodyTree, is a robot with revolute joints and two degrees of freedom.

Simulate using — Type of simulation to run

Interpreted execution (default) | Code generation

• Interpreted execution — Simulate model using the MATLAB^® interpreter. This option shortens startup time but has a slower simulation speed than Code generation. In this mode, you can debug the source code of the block.

• Code generation — Simulate model using generated C code. The first time you run a simulation, Simulink^® generates C code for the block. The C code is reused for subsequent simulations, as long as the model does not change. This option requires additional startup time, but the speed of the subsequent simulations is comparable to Interpreted execution.

Tunable: No

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"robotmaniplib/Gravity Torque"

Example: add_block("robotmaniplib/Gravity Torque","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

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

Version History

Introduced in R2018a