The Mobility Modular Technology Demonstrator (MMTD) is a test vehicle for evaluating surface mobility technology.  The MMTD vehicle consists of a single-piece chassis and six independent wheel modules that can be repositioned or removed. The MMTD is used in a variety of studies of terrain-vehicle interaction, as well as motion control. As such, a Hardware-in-the-Loop (HIL) data acquisition and control system (DACS) is required that can be reconfigured for each study.

The Data Acquisition & Control System (DACS) was developed using RT-LAB and an OPAL-RT Simulator.  The DACS architecture consists of an on-vehicle subsystem and a remote operator subsystem. The on-vehicle subsystem deterministically (i.e. in real-time) acquires and processes sensor information, drives the vehicle’s actuators, and stores data on a local hard drive. The operator subsystem provides a graphical user interface (GUI), as well as a motion command device, such as a “joystick”. The two subsystems are linked wirelessly under the IEEE 802.11b data transfer protocol. This protocol was chosen because it is the standard for consumer electronics, and therefore compatible transceivers are readily available. The wireless link is used to send motion commands to the vehicle, as well as return sensor information for display on the GUI.

The real-time hardware for implementing control loops and collecting data sits on the vehicle and hence low-mass and compact volume are important qualities. The system runs off of a twelve volt battery and utilizes power efficiently to maximize the operation time. The system is capable of writing all data to a local hard drive. The data acquisition and control is programmed in the RT-LAB MATLAB/Simulink software environment. The real-time system has the following I/O capabilities: PWM, Analog Inputs, Digital Inputs, Quadrature Encoder Inputs, and Video Frame Grabber Inputs.  The requirements for these I/O channels are met using Sensoray 626, Sensoray 611, and OPAL-RT OP5110 FPGA-based PCI cards.

A remote laptop is used to monitor and control the vehicle. The laptop runs TestDrive GUI software which interfaces with the real-time system. The RT-LAB software has a graphical user interface, where “virtual instruments” are linked to any pre-selected state variable or I/O parameter of the real-time system. Using the software, the vehicle operator updates any preselected control or data acquisition parameter in the real-time system on-the-fly. The system has the provisions to interface with a “joystick,” to control wheel speed and position. Commands are sent to the real-time system wirelessly using the IEEE 802.11b

Author(s): Keith Kukolich,
Narrator: Keith Kukolich,

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