This tutorial will explain how to use the C HAPTIX client library
requesting a description of the hand, sending new joint commands, and receiving state updates.
We assume that you have already done the installation step.
In this tutorial we include a very basic controller that applies a sinusoidal function to all the hand joints. First, you should compile your controller and link it to the haptix-comm library.
Open Visual Studio 2013 and create a new project for your hand controller. Click
Visual C++, and select
Win32 Console Application
from the right side window. Select an appropriate name for your project, for
OK, and then, click on
Replace the source code from your current project with our basic controller. Copy the code from here and paste it in your current project.
Add the following line at the beginning of your source code:
Note: Skip this section if you are using the 32-bit SDK.
Click on the dropdown menu with the
Win32 option in the toolbar and select
After that, look for the
Active solution platform dropdown menu and select
<New...>. Click on
Type or select the new platform and change
, and then, click the
Open the Property Manager view by clicking on
Manager. This will allow you to use the property sheet provided by the HAPTIX
library SDK. Move to the
Property Manager tab and right click on your project.
Add Existing Property Sheet.... A new popup window
will appear. Browse to the folder where you downloaded the HAPTIX client library
SDK and select the property sheet named
haptix-comm. This will handle all the
dependencies for your project.
Switch the target build type from
Release using the upper toolbar.
Then, click on
Build Solution to build your controller.
Install the following packages required for downloading and compiling the example:
sudo apt-get install wget cmake build-essential
Create a new directory named
haptix_controller for this tutorial:
Create a build directory and compile the source code.
On the Linux machine, double-click on the
haptixStart desktop icon to start
Your code should be ready to be executed using Visual Studio. Click on
Start Without Debugging... (alternatively you can press Ctrl+F5).
Note: if the Windows firewall is enabled, it will show a Window called "Windows security alert. Windows Firewall has blocked some features of this program" asking for permissions to run the recently compiled application. You could leave the default option ("Private networks, such as my home or work network.") and click on "Allow access".
Go to the Linux machine where you want to run your controller code. Open a
terminal and go to the
build/ directory where you have your controller
Start the controller:
While your controller is running, you should see your fingers following a smooth trajectory in Gazebo.
Error: Unable to access http://bitbucket.org/osrf/haptix-comm/raw/default/example/hx_controller.c
The HAPTIX C API is composed of five C function calls:
optional for the Gazebo simulator, but are included for compatibility with MuJoCo.
hx_robot_info() requests information from a given device.
In this tutorial, our device is a hand simulated in Gazebo. Note that this call
blocks until the response is received.
The parameter to
hx_robot_info() is a
hxRobotInfo struct that
contains the number of motors, joints, contact sensors, IMUs and joint limits
for the requested device. It also includes the update rate, which is how frequently the
device updates. If we have a valid response, the returned value is
We have included in our example a helper function
printRobotInfo() that will
print all the received fields for debugging purposes.
Once we confirm the robot information we can start sending commands for
controlling the hand. The function
hx_update() is in charge of sending a new
command and receiving the current state of the hand.
First of all, we need to fill a
hxCommand struct that contains the positions,
velocities, and gains for each joint. Check the haptix-comm API
for a detailed view of the
hxCommand struct. In our case, we are modifying the
position of all the joints according to a sinusoidal function.
The first parameter to
cmd, is the command that we want to send to the device, which we already
filled in. The second output command
sensor is passed to the function; it will contain the
state of the hand after applying the command.
We have included a helper function
printState() that shows all the state
information for debugging purposes. Similar to
hx_robot_info(), the function
hxOK when the command was successfully sent and the
state has been received.
Usually you will receive a message from the command line launched by Visual
Studio with an error message
hx_robot_info() Service call timed out. This
means that the communication to the Gazebo Linux server failed.
First check: Are both machines in the same network and can reach each other? Simply using the ping command from both (windows command line and Linux shell), should be enough to check connectivity. If it is not working, there is a problem in network configuration, be sure that both are connected to the same network.
Second check: Is the communication layer using the right network interface?
Double check that you have set the
IGN_IP properly in both Gazebo Linux server
and Windows. In Windows this can be done from the Windows command line
To be completely sure, logout from your user session, login again and open Visual Studio.
Third check: Is the Windows firewall affecting the communication? It can be disabled from the Windows Control Panel (remember that there are different profiles in the Windows firewall, be sure of disable them all) and try to launch the Visual Studio application again.
Fourth check: Is the router cutting the communication? Several solutions: Login into the router, disable any kind of firewall. If you can not do that, connect both machines using an ethernet cable directly. You will need to manually setup both in the same subnet (192.168.X.Y/255.255.255.0 and 192.168.X.Y+1/255.255.255.0).
Probably you have an incorrect IP adress set in the
The error means that there is no connection from the Linux simulator back to the Windows system. It is probably because of the Windows Firewall.
If you are using a Wireless connection, it could happen that latency is making the interaction fail. Please try using a wired connection.
If by an error you pressed the wrong button, you can access to the
Firewall advanced security from the Windows control panel, go to
rules and remove the ones with the name
ConsoleApplication (or the name that
you gave to the application).
Another option is to modify your application name, in the
name (not the solution name) that appears in the
Solution Explorer window.
Clean, rebuild and run again.