The Challenge: Creating a robot controlled by a remote PC that is capable of surveillance, motion, and awareness of its surroundings.
The Solution: Designing a virtual display and control system using NI LabVIEW software and PXI hardware to detect and control distance changes in a sensor, movement speed, and motor direction.
We chose NI PXI as the core of our Big Blue robot. It controls the webcam, sensors, and motor used for surveillance purposes. PXI hardware sends values to the motion controller to drive the motors. When the sensors detect any change in distance, the change is also detected by the PXI system. The LabVIEW front panel shows the webcam image. The sensors emit sound waves and when the waves hit and reflect off an object, there is a change in output. Value changes detected by the sensors are output in the respective digital I/O (DIO) ports of an NI TBX-68.
The webcam has a control panel page that rotates the webcam. The system uses the webcam control panel and displays it on the LabVIEW front panel through the router (the router and the PXI system are linked). User data that is input via keyboard or joystick passes through the NI UMI-7764 ports to the motion controllers to drive the motor. All functions are remotely controlled using the LabVIEW remote panel connection (see Figure 1).
Software Development
Using NI data acquisition and the PXI I/O interfaces, the system captures information from the motion controllers and joysticks. Using the information acquired, the program prompts the user to input values into the Distance Amount textbox on the front panel (see Figure 2) and press the direction button to move the robot. However, if the user uses a joystick, the direction the robot moves in corresponds with the joystick.
After initializing the TBX-68, the program reads the values from it. If an object is detected by a sensor, the DIO port that connects to the sensor changes from low to high. This feeds into the program and changes its value. The PXI system and remote PC are connected to a router through a wireless network card, whereas the webcam is directly connected to the same router. The program reads the webcam control panel through the router’s network and displays it on the front panel. As the remote client PC belongs to the same network as the PXI device, the remote panel connection uses static IP. At the remote PC, a joystick can control the robot. Using TCP/IP data packet sending, the system sends all the values to the PXI system to drive the motion controllers. A separate VI runs on the remote PC to send the data packets.
Conclusion
When the program first starts, it initializes the motion controllers, joysticks, and webcam. We can achieve distance movement by entering values and using the direction button or a joystick. The program displays the full control panel page of the webcam along with commands to interact with the user. When the robot goes too near an object, the LED changes from green to red. Also, when the Big Blue robot is low on power, the voltage monitor changes from blue to red. This feature uses the TBX-68 DIO port and takes the inputs from 12 V 33 A batteries, which are then converted to low or high inputs using a circuit board. The remote client PC accesses and controls the PXI system using the remote panel connection and any actions we perform on the PXI system can also be done in the remote client PC.
National Instruments provides a graphical system design platform for test, control, and embedded design applications that is transforming the way engineers and scientists design, prototype, and deploy systems.
Print
PDF
