Ground Robotics, Agriculture, & Heavy Machinery

Ground robots and other slow moving platforms present a significant challenge for many INS sensors. Slow moving platforms typically do not experience sufficient acceleration during normal operating conditions to perform dynamic alignment. Dynamic alignment occurs when there is sufficient motion present to allow an INS sensor to observe heading based on the correlation between the measurement of acceleration from the IMU and the measured change in velocity measured by the GPS receiver. While dynamic alignment works well for platforms such as fixed wing aircraft, it is typically not suitable for slow moving ground vehicles. As such most ground robot navigation systems rely magnetic sensors to estimate heading. Deriving accurate heading using magnetic sensors is notoriously difficult for ground vehicles, due to to the presence of ferrous material in both the vehicle and the local environment such as rebar in concrete, the vehicle itself, and other nearby objects. Achieving accurate heading measurements using magnetic sensors is only possible in applications where the magnetic environment can be carefully controlled by the user, and where a magnetic calibration is accurately performed on the vehicle itself using a technique known as a hard/soft iron calibration. In most real-world applications, the user has little to no control over the quality of the surrounding magnetic environment, and performing a proper magnetic calibration is a very time consuming endeavor, and in some cases is not possible for certain platforms such as heavy machinery.

The VN-300 is the ideal navigation sensor for outdoor ground robots and heavy machinery due to its ability to accurately estimate heading relative to true North without any reliance on magnetic sensors. This enables autonomous control in conditions where the magnetic environment isn't predictable or for vehicles such as heavy machinery where magnetic calibration and the use of magnetic sensors in general is not feasible. With heading accuracies of better than 0.3 degrees possible, the VN-300 is also ideally suited for agricultural use, where precise heading accuracies are required.


Quad-copter, Rotorcraft, & Aerostats

As with ground robots, slow-moving aircraft also present a challenge for INS sensors due to their lack of sufficient motion required to estimate heading directly based on dynamic alignment. Traditionally magnetic sensors have been used in these applications as the primary method of determining heading during periods of low dynamic motion. While the magnetic environment is much more predictable in aerial applications than it is for ground vehicles, it still requires the user to perform an accurate magnetic calibration in order to achieve any reliable level of accuracy. These magnetic calibrations are very difficult to perform for most aerial hovering platforms. Also, in many cases the user must recalibrate when any configuration changes is made, such as when batteries or cameras are replaced.

The VN-300 is an ideal navigation sensor for these slow-moving aerial platforms, due to its ability to accurately estimate heading relative to true North without any reliance on magnetic sensors. Another significant advantage provided by the VN-300 for this type of application is its ability to accurate estimate heading from startup prior to motion. This is an absolute must for applications where the vehicle is required to know its heading to within a certain level of required confidence prior to takeoff. Traditionally the only other method of establishing accurate heading without reliance on magnetic sensors is by using gyro-compassing. This techniques requires the use of a highly accurate and very expensive fiber optic gyro which is capable of direct measurements of the earth's angular rate vector, which in return provide a means of estimating true heading. Not only does the VN-300 provide a significant cost savings over FOG gyros capable of gyro-compassing, it also provides an even more significant weight reduction, which is crucial for hovering aerial platforms.

Marine Antenna Stabilization

Marine Antenna Stabilization

Maritime VSAT satellite communication require stabilized antennas to remain pointed at a known point in space aligned with the known vector to a satellite to ensure continuous data transmission and reception. In many cases regulations place hard limits on the pointing accuracies requiring transmission to cease when pointing accuracy cannot be maintained to within a specified required tolerance. For VSAT applications this high accuracy tracking must be maintained 24-7, in a wide variety of sea conditions all while the antenna is mounted to a vessel that experiencing significant rotation, heave, surge, and sway. Most traditional INS sensors with sufficiently good gyros, are capable of estimating the attitude of the dish accurate enough to maintain antenna alignment in mild to moderate sea conditions, however many actually struggle to maintain accurate heading estimates during cases when little to no motion is present in the vessel such as when it is at port or in calm waters. In these calm conditions there isn't sufficient motion to maintain an accurate heading estimate based on dynamic alignment alone, and as such most INS sensors have to resort to using the magnetic sensors to maintain alignment. For VSAT applications magnetic calibration is very difficult to achieve accurately, since the vessel moves independent to the satellite dish. Without an initial heading estimate, or when an inaccurate heading estimate is given by the magnetic sensors, many VSAT systems require long startup times, during which a elaborate and complex sky search is performed to obtain initial tracking.

The VN-300 eliminates two of the biggest problems VSAT customers face when using traditional INS systems, lack of tracking during stationary conditions, and lack of accurate heading at startup. By utilizing GPS moving baseline RTK techniques with two GPS antennas, the VN-300 is capable of accurately estimating heading directly without any reliance on magnetic sensors. It can also obtain a heading measurement within minutes after powering on at startup. This enables a VSAT antenna utilizing the VN-300 to instantly acquire lock immediately at startup without any need for a manual sky search. It also eliminates any tracking problems experienced during calm sea conditions, by eliminating the need to use magnetic sensors. The VN-300 also provides exceptional tracking performance even during harsh sea conditions due to its combination of low drift gyros, accurate scale factor and axis alignment, and ultra-low latency high update rate attitude measurements.