High quality GPS/GNSS receiver & AIM+ can deal with radio frequency interference from nearby infrastructure installations.
The vehicle's forward speed determines the point cloud spacing along the bunk. Currently, this speed is normally about 7-10 km/hr, and the lidar runs at 100 Hz, yielding a point spacing of about 50 mm. The next version will be able to operate at up to 15 km/hr. In the future, the vehicle could be fully autonomous, freeing the driver for other duties. Manabotix has tested the lidar scanner both by day and by night and reports that performances have been very consistent under all ambient conditions.
An onboard processing platform combines the lidar scanner’s measurements with the GNSS positioning solutions to resolve quantities of feed remaining. These are then communicated back to a central data service for subsequent reporting and action.
See the MLA automated feed bunk scanner in action
The Role of the GNSS Receiver
The Septentrio AsteRx-U GNSS receiver in the bunk scanner acts as a rover in an RTK set-up, paired with a base station at most a few kilometers away, achieving a horizontal positional accuracy of 5 mm across the site. This extreme accuracy is essential to optimize the accuracy and precision of the volumetric solution.
Feedlots consist mostly of pens and roads on a flat terrain. Nevertheless, they also contain structures — such as huge silos and steel posts to hold up very large shade cloths — that can cause multipath. Additionally, the area may be subject to radio frequency interference from nearby infrastructure installations. This was, in fact, the case at one of the feedlots during some recent experiments.
Septentrio’s multi-constellation and multi-frequency GNSS receiver with helps to mitigate these issues. The ability of a GNSS receiver to handle multiple frequencies from multiple constellations to calculate its position is essential to minimize errors. The use of multiple frequencies is the most effective way to remove position calculation errors that are due to signal delays in the Earth’s ionosphere and provides more immunity to interference. The use of signals from multiple constellations greatly increases the number of satellites in the field of view. This reduces the signal acquisition time, improves the accuracy of the position and time solution, reduces the problems caused by obstructions in the view of the sky (such as buildings and foliage), and improves the spatial distribution of the visible satellites, reducing the PDOP. Therefore, the AsteRx-U GNSS receiver is able to compute the most accurate and reliable position. “Even on cold starts, it gets a position solution very quickly,” says Dr. McCarthy.
The Choice of Septentrio
Manabotix chose Septentrio for the positioning solution because it already had a long-term relationship with the company and trusted its ability to provide a solution that matched its specification requirements, explains Dr. McCarthy. “They’ve always had what we’ve needed in terms of a commercial model and a technical model. We are an integrator, in effect. If we don’t have confidence in the equipment that we are integrating and selling, we could be quite exposed. We have confidence in them from a technical level, which allows us to always deliver on time and within budget.”
“We also really liked working with Septentrio and with their Australian distributor, GlobalPos” Dr. McCarthy says. He praises “the accessibility of the tech support,” adding, “We do not have all these barriers with sales guys or business development guys. You are talking directly to the people who know what they are doing. Then, if you want something a little bit different, a little more bespoke for your solution, they are also on board to try to work with you to get it. They are very robust and reliable.”
While the source of the wideband interference experienced at one of the experiment feedlots is still undetermined, the on the Septentrio GNSS receiver enabled Manabotix to mitigate it and get back online. “We were able to also provide raw data dumps back to Septentrio’s headquarters in Belgium,” Dr. McCarthy recalls, “and they were able to decant that data and provide us more instructive feedback with our troubleshooting process. This is really useful and makes a big difference for us, because we want to provide the best technical solution and we don’t want to get bogged down trying to solve everyone’s problems.”
Manabotix has demonstrated with a high level of confidence that its solution is far more accurate and precise than human predictions, based on extensive experiments at several feedlots in different geographic areas, under different operating conditions, both day and night. It was determined that humans generally underestimate volumes, particularly very large ones. By contrast, Manabotix’s solution has an accuracy better than 10 kg (for all feed remaining masses assessed, from 0 kg to more than 500 kg) and a precision with an r2 (coefficient of determination) of about 0.99. Therefore, it is very repeatable and the error model can be easily described through statistical analysis.
At about A$400-A$500 per ton and rising with the drought conditions, feed costs are up to A$350,000 a day for Australia’s largest feedlots, and operators are always required to perform a fine balancing act between feeding their cattle too much and not enough. Therefore, even a 1% improvement in feed utilization would have a massive impact on their profits. Additionally, if the bunk scanner were mounted on an autonomous vehicle, that would free up employees to perform other valuable tasks. Finally, the greatly increased feed measurement accuracy improves the health of the animals, by ensuring that they are neither underfed nor overfed.
"This could be revolutionary, because it has always been done a certain way and this is a whole paradigm shift,” says Dr. McCarthy.
- Brochure: GPS / GNSS Spoofing - types, how to detect and mitigate
- Brochure: GPS / GNSS Interference - counteracting jamming