Overview of the LabVIEW Robotics Simulator

Publish Date: Dec 22, 2015 | 8 Ratings | 3.12 out of 5 | Print

Overview

Simulation is critical for robot development; it allows developers to validate their design and algorithm more efficiently and effectively. The LabVIEW Roboics Simulator, based on the Open Dynamics Engine (http://www.ode.org), is a physics-based simulator to emulate your robotics design. This tutorial highlights different components of the LabVIEW Robotics Simulator and demonstrates how you can take a custom 3D CAD model design into the LabVIEW Robotics Simulator.

Table of Contents

  1. Robotics Design
  2. The  LabVIEW Robotics Simulator
  3. CAD Model Importer
  4. Robot Simulation Model Builder
  5. Robotics Environment Simulator Wizard
  6. References

1. Robotics Design

There are many steps to ensure a successful robot design for any application. The design phase of the platform is perhaps the most challenging of the entire process. The engineers will have to ensure that the design not only fulfills the needs, but also is practical and plausible. By translating ideas into CAD drawings and models, it allows the engineers to quickly prototype the design.

The LabVIEW Robotics Simulator can further extend the design process through physical simulation of the design. It can work with various CAD software such as SolidWorks and Google SketchUp via COLLADA (.dae) file format. Let’s take the Robotics Starter Kit for example, the robotics platform was first designed in SolidWorks to ensure the design fulfill the physical requirements.

 

 

Figure 1. LabVIEW Robotics Starter Kit in SolidWorks

Figure 2. Convert to COLLADA (.dae) File using Blender

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2. The  LabVIEW Robotics Simulator

There are three major components of the LabVIEW Robotics Simulator and we will discussion each of the components in this section.

  • CAD Model Importer
  • Robot Simulation Model Builder
  • Robotics Environment Simulator Wizard

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3. CAD Model Importer

The CAD model importer allows you to import your models with the extension .ive, .dae, and .wrl into the LabVIEW Robotics Simulator.

Open Robot Simulation Model Builder from Tools>>Robot Simulation Model Builder…, and follow the steps below to build your simulated robot model.

 

1. Right-click the User Model Library folder in the Model Library and select Add

Models from the shortcut menu.

2. Select a model file from the local directory. The Robot Simulation Model Builder

supports model files with the extension .ive, .dae, and .wrl. Click OK.

3. In the Computer Aided Design (CAD) Model Importer dialog box that opens,

create physical models for the robot model and modify the properties of the

physical model.

  1. You can drag one node to another to make simple rearrangement to the model structure. You can also create a dummy node to help you arrange the nodes, e.g. dragging some nodes to a dummy node and create a box to include all nodes by creating on the dummy node.
  2. If you create physical model for the parent node, then you cannot create physical model for its children nodes any more.
  3. You can drag the x,y,z axis and 3 quarter-fans to roughly modify the related posture of the physical model to the visual CAD model. To make more precise modification, use the “Position” and “Rotation” properties in the “Properties” list. (The Rotation X,Y,Z are the global Euler angles of the physical model).

  1. Properties that typically need modification are: Steel, Length, and Mass.

 

4. Click OK to save the robot model with edited properties to a specific path and

close the CAD Model Importer. In the Robot Simulation Model Builder, a new

component adds to the User Model Libray folder.

  1. If you save the part under default folder(you can create sub-folder), the part will be automatically loaded in the Model Library Tree, or you have to manually load the part into the Model View of Robot Simulation Model Builder by clicking the “Import” button.
  2. A folder named “PartName + RSC” will be created to store the resource files of the model, DO NOT modify this folder manually.

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4. Robot Simulation Model Builder

The Model Builder allows you to add additional components, sensors, and actuators to the simulation model. You can also use the model builder to position different parts of the robot and define all the joint types on the robotic system.

To assemble the robot in model builder

  1. Select a component or robot model in the Built-in Model Library folder and

preview the component in the Model Preview section.

  1. Right-click the component or robot model and select Add to View from the

shortcut menu to add the robot model to the Model View.

  1. Position Parts

In the Model View section, edit the position of each component or robot model that you add to assemble a simulation robot. Use the 3D-Controller to move a robot model or component along the X-, Y-, and Z- axes. The following screenshot illustrates a 3D-Controller.

To make more precise modification, use the “Position” and “Rotation” properties in the “Properties” list.

 

  1. Create Joint to connect parts

In the Parts List or Parts Hierarchy section of the Robot Simulation Model Builder, drag one robot component onto another component to add a joint between the two components.

  1. Right-click a joint and select Joint Type from the shortcut menu. Select a joint type. You can use the following types of joints. 
    • Fixed Joint—Fixed joints maintain a fixed relative position and orientation between two bodies. 
    • Slider Joint—Slider joints allow two bodies moving along an axis, but this kind of joints constrain the motion of a rigid body point along a line.
    • Ball Joint—Ball joints allow rotational movement between two bodies. 
    • Hinge Joint—Hinge joints are freely moving joints which allow extensive movement in one plane.

 

  1. Right-click a joint and select “Set Motors” to attach or create a new motor to the joint to actuate the joint. Without a motor, a joint can’t be controlled and therefore is passive. Click the joint to see the property of the attached motor at the bottom of the Properties list.

NOTICE: One motor can be attached to multiple joints to control the joints at the same time. To detach a specific motor, select Set Motors and click on the currently selected motor one more time. The Robot Simulation Model Builder automatically deletes motors that are not attached to any joints.

Joints velocity/position = Motor velocity/position * Rate

 

  1. You can click Select Branch in the short-cut menu to multi-select a whole sub-branch of parts and position them together. Click the Set Root to set the selected item as the root of the robot, which is usually the base platform of the robot.
  2. Exporting Robot Models

After you finish designing the robot model, you can export the robot model with your configuration. Click the Export button to save the robot model as an .xml file. If you

Export the robot model to the default data directory of LabVIEW Data\Robotics\Simulator\Model\Config\, the new robot model appears in the

User Model Library of Model Library. If you save the robot model to other path

that you specify, the robot model does not appear in the Model Library.

 

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5. Robotics Environment Simulator Wizard

The robotics environment simulator wizard allows you to build the environment for simulating your robots.  At the end of the wizard, you can start developing your control algorithms in the environment.

 

  1. Open Robotics Environment Simulator by click File>>New…, and Select Robotics Project, Robotics Environment Simulator.
  2. Switch to the Robot tab page, and drag the robot to the Simulation Scene. Following the tips on the left-bottom to position the robot.

  1. You can modify the robot by selecting the robot and click the Edit button

  1. You can also put obstacles into Simulation Scene. Double click an item in Environment tab page to replace the scene environment. Drag an item in the Sensor tab page onto a robot for fast sensor installation.

Click Next and save the project, a Project Explorer will be popped up. Open the Vi to write control code for your robot.

 

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6. References

NI LabVIEW Robotics Module

 

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