The U.S. military's unmanned combat vehicles encounter technical bottlenecks
2024-08-10
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A U.S. military unmanned vehicle fleet being tested in the Middle East. Image courtesy of the U.S. Marine Corps
Comprehensive compilation Zhang Haotian
Several unmanned vehicles belonging to the US Army were driving in a convoy on a highway in Saudi Arabia. At first, the autonomous driving function of these unmanned vehicles worked normally. But when the convoy encountered common objects such as speed bumps or overpasses, the sensors on the vehicles determined that there was an insurmountable obstacle ahead. Subsequently, the unmanned vehicles exited the autonomous driving mode and required humans to take over driving to avoid risks.
The unsuccessful test earlier this year is a microcosm of the difficulties faced by the U.S. military's unmanned combat vehicle program. The U.S. "Breakthrough Defense" website said that the U.S. Army hopes to deploy unmanned combat vehicles with actual combat capabilities from 2028, but the technical bottleneck caused by the complex ground environment has weakened the outside world's confidence in the project, and it cannot currently achieve the fundamental purpose of "protecting human soldiers."
The U.S. military's interest in unmanned combat vehicles began in the early 21st century, with plans to develop three types of vehicles, ranging from light to heavy. According to the initial plan, the military will invest at least $900 million in the project from 2023 to 2029. In the third quarter of this year, all shortlisted contractors will deliver prototypes for hardware demonstration so that the military can make the next decision in 2025. At the same time, the U.S. Army has modified a batch of vehicles to test autonomous driving-related software around the world.
An officer who participated in the test told Breakthrough Defense that autonomous driving technology is not yet mature. In order to avoid traffic accidents on public roads, there must be a "safety officer" on duty in the car, and the speed cannot be too fast. Even so, the performance of the test vehicle in the real environment is still very unstable, and there are often abnormalities such as mistaking common objects for obstacles. Project director Michael Cadieu said that technicians are trying to solve the problem of misidentification and plan to update the software every 6 months.
Another test conducted at Fort Irwin in California also exposed the shortcomings of the unmanned combat vehicle. Due to the unreliable autonomous navigation function of the vehicle, the test vehicle had to drag a cable for transmitting instructions, and a support vehicle with five operators followed behind. Breakthrough Defense pointed out that in the vision of the US military, unmanned combat vehicles should replace humans and perform high-risk missions under enemy fire, but the current situation is obviously inconsistent with the original intention.
"We should have soldiers retreat further," said Jeffrey Norman, a retired U.S. military general who worked on the unmanned combat vehicle project team. "Whether the enemy firepower comes from artillery or missiles, the support vehicles in the rear are very vulnerable to attack." Doug Bush, head of U.S. Army acquisition affairs, said that the difficulties currently encountered by unmanned combat vehicles are not surprising, which is largely related to the complexity of ground combat. Although unmanned driving platforms have been put into actual combat in the air and at sea, in the land environment, due to the large number of obstacles and dense population, unmanned systems face more difficulties.
Unlike previous unmanned vehicles that were responsible for minesweeping and reconnaissance missions, the next generation of unmanned combat vehicles envisioned by the US military are truly front-line combat units. They play a pioneering role in large-scale offensives, counterattack while bearing enemy firepower, and human operators only need to "supervise the battle" in the rear. To realize this vision, reliable remote control is essential. At present, only wireless communication can allow humans and machines to maintain a sufficiently safe "confrontation distance". However, when the two sides are too far apart, there are obstacles or electronic interference, the unmanned vehicle will "lose contact".
U.S. military sources said that in order to keep the remote control signal stable, the reasonable distance between the operator and the unmanned combat vehicle is 1,000 to 2,000 meters. Of course, this is an ideal situation in open terrain. If trees or buildings appear on the offensive route, the "standoff distance" may drop sharply to about 500 meters, increasing the risk of the operator being attacked. "Sometimes, the two sides may communicate frequently, requiring a large amount of bandwidth to be allocated," explained Jeffrey Norman. "Other times, the unmanned combat vehicle basically remains silent and operates according to pre-set procedures. The operator only needs to monitor and confirm."
Because of concerns that unmanned combat platforms will become "robot killers", the US military requires such platforms to maintain data interaction with human soldiers at all times so that soldiers can make decisions before opening fire. This requires technicians to fully demonstrate how much autonomy unmanned combat vehicles should have in different scenarios. If the vehicle requires manual confirmation before executing any instructions, it will not only go against the original intention of developing unmanned combat vehicles, but will also overwhelm the data transmission system.
Some people argue that in order to truly exert reliable control over unmanned combat vehicles, it is necessary to enrich the types of control links. To this end, it is necessary and feasible to introduce low-orbit satellite communication methods similar to "Starlink". Glenn Dean, head of the US Army's ground combat system project, said in an interview with "Breakthrough Defense" that satellite communications also have shortcomings, such as signal delays. "We want the longest possible remote control distance and high-definition remote video transmission, but the first prerequisite for effective control is low latency," he emphasized. For unmanned vehicles traveling at speeds exceeding 20 miles per hour, the delay should not exceed 250 milliseconds, otherwise it will cause the rear control personnel to be unable to correct or "overcorrect" the deviation in the vehicle's driving in time.
The Army major general explained that signal delay has little impact in most cases, but if it happens at the moment when the tank opens fire, it may cause the target to be missed or even friendly forces to be hit by mistake. The U.S. military will simultaneously promote basic technology research and development and testing in real environments in the next two to three years, with the goal of finding a balance between "autonomous decision-making" and "human intervention" to accelerate the "unlocking" of the actual combat potential of unmanned combat vehicles and keep human soldiers as far away from the front line as possible.
Source: China Youth Daily Client
