Conference Session B8 Paper 76 Disclaimer—This paper partially fulfills a writing requirement for first year (freshman) engineering students at the University of Pittsburgh Swanson School of Engineering. This paper is a student, not a professional, paper. This paper is based on publicly available information and may not provide complete analyses of all relevant data. If this paper is used for any purpose other than these authors’ partial fulfillment of a writing requirement for first year (freshman) engineering students at the University of Pittsburgh Swanson School of Engineering, the user does so at his or her own risk. ROTARY LiDAR SENSORS FOR USE IN FULLY AUTONOMOUS VEHICLES Josh Vinoya, [email protected], Sanchez, 5:00, Andrew Parker, [email protected], Mena Lora, 1:00 Abstract - Notable innovations in the automotive field help reduce human error by monitoring and regulating a car’s internal systems in order to protect riders from preventable accidents. The next significant improvement in automobile safety will come from real-time digital image renderings provided by 3D Light Detection and Ranging (LiDAR) sensors. Velodyne’s model HDL-64E LiDAR sensor is a candidate for use in fully autonomous driving because its patented rotary head can generate up to 2.2 million data points every second, while still being compact enough to fit on a car’s roof. Using the HDL-64E as a data source, engineers are able to program its on-board computer system safely guide it through challenging and diverse environments. A complete understanding of how the model HDL-64E works was collected using the product guide, manual, and 3D CAD models. Labeled diagrams and detailed explanations of the sensor’s components are provided for the reader. The paper then notes the sensor’s application and significance to autonomous driving, with emphasis on recent publications due to the ongoing innovations within this topic. Finally, the paper presents and discusses the ethical dilemmas within this field to complete the investigation into LiDAR sensors for use in selfdriving cars in addition to its potential role in improving the quality of life. Key Words—Automobile Safety, Autonomous, HDL-64E, LiDAR Sensor, Self-Driving, Velodyne LiDAR SENSORS AND SELF-DRIVING CARS Many similarities can be drawn between LiDAR systems and radar. Instead of using radio waves however, the lasers within the LiDAR housing emit a carefully timed pulse of light which bounces off an object and is returned to the sensor. Velodyne’s HDL-64E gathers millions of these data points every second, generating a very dense point-cloud of information which is then fed into the car’s on-board computer, allowing it to safely navigate through dangerous environments. There were more than 6 million car accidents on US roads last year, with distracted driving as the number one cause of crashes [1]. LiDAR sensors are the future of fully autonomous driving, with the power to considerably reduce the University of Pittsburgh Swanson School of Engineering 1 Submission Date 10.02. 2017 tragic results that often accompany these accidents by having a significantly lower accident rate than even the most experienced driver. Automobiles affect all of us almost every day, and eliminating human error from the dangerous task of driving has the potential to save thousands of lives every year. It is always important to consider ethics when new technologies are created. The ethical dilemmas surrounding autonomous driving are complicated because although it will save lives, accidents will occur and the liability for those accidents is still unclear. This paper takes an in-depth look at the technology itself, the application of LiDAR to autonomous driving, the significance of self-driving cars, and the ethics behind them. SCIENCE BEHIND LiDAR SENSORS Light Detection and Ranging (LiDAR) sensors are based around time-of-flight measurements to generate a digital image of the sensor’s surroundings. A 2016 article in Automotive Industries titled Laser vision for self-driving cars details how LiDAR sensors function, as well as their role in driver assistance systems [2]. It describes how the sensor emits a carefully timed pulse of light which exits the sensor, hits an object, then reflects back to a detector panel. The HDL-64E emits a Class 1 Eye-Safe laser with a wavelength of 903nm [3]. (A Class 1 Eye-Safe laser is a sound choice for use in this application because it does not damage human eyes unless an iris is exposed to it for an extended period) The sensor then knows the time of flight of the light, as well as the speed of the light (299,792,458 m/s). It calculates the distance to the object using the equation 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 = 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 ∗ 𝑇𝑖𝑚𝑒 or 𝑥 =𝑣∙𝑡 [Eq. 1] [Eq. 1] The computer within the sensor makes millions of these calculations every second in order to generate a dense pointcloud of information about its environment. The HDL-64E has 64 of these carefully aligned lasers inside its housing [4]. Thirty-two reside in the upper half, and thirty-two are in the lower half. Currently, one of the main factors contributing to the high cost of the sensor is the extensive manual labor that is required to install, and then align the lasers [5]. The materials Andrew Parker Josh Vinoya themselves are not the largest cost when constructing the sensors. According to Velodyne’s product manual page, the HDL64E can generate up to 2.2 million data points every second in dual return mode, or 1.3 million every second in singular return mode [3]. The sensor has a range of up to 120 m and a typical accuracy of ±2 cm [3]. This results in an extremely detailed point-cloud of data to be used in the car’s on-board computer systems. The HDL-64E can detect objects from +2.0o to -24.9o for an impressive vertical field of view of 26.9o. Shown below is Velodyne’s model HDL-64E S3. As shown below, it stands 283 mm tall and has a diameter of 223 mm. Because of its design, it can easily be secured to almost any vehicle without needing to significantly modify the vehicle’s construction. driving. While they are adequate in basic pattern recognition, an IEEE article discussing On Board 3D Object Perception in Dynamic Urban Scenes explains that they are prone to error in low illumination and diverse weather conditions [6]. In addition, they provide only a video feedback, not a 3-D point cloud of data, so the computer systems make mistakes more frequently than those powered by LiDAR sensors. Flash LiDAR systems are smaller, stationary units that are placed in several locations around the outside of a vehicle [2]. According to an Automotive Industries article, these systems operate by sending out a flash of light and registering each pixel as it returns to the sensor [2]. This is a more cost-effective solution, however they do not gather as much data as rotary LiDAR systems, and also are more prone to blind spots. These sensors are currently being used for driver-assistance systems such as adaptive cruise control and self-parking vehicles. However, to be used in fully autonomous driving, the sensor must be powerful enough to provide enough data for the car to make the thousands of decisions every second necessary to operate a motor vehicle. APPLYING LiDAR TO AUTONOMOUS DRIVING A sensor of complex caliber will undergo a series of linear steps set by a scripted code that will command the computer to execute the commands at a given moment. To be seriously considered for use in autonomous driving, a sensor must be able to provide enough information to that computer system for it to be able to detect and identify its surroundings, classify the type of situation that the automobile is in, and execute the specific command prompted. We will focus on the process of surveying and detecting undertook by the LiDAR sensor. FIGURE 1 [3] HDL-64E Rotary LiDAR Sensor The sensor can operate effectively in the temperature range of -10oC to +65oC [3]. This allows for it to be used in many driving conditions, and thus there is not a great danger of it failure due to a temperature malfunction in regular use. The HDL-64E is a rotary LiDAR sensor, so its patented rotating head can spin anywhere from 300 RPM (5 Hz) to 900 RPM (20 Hz), allowing the user to select the density of the data point cloud, and therefore the image resolution created. A slower rotation speed will result in a denser point cloud, while a faster rotation speed will have a higher refresh rate. The sensor will continue to gather the same number of data points per second independent of spin rate. An important advantage of the rotary design is the horizontal field of view of 360o. In a SAE International article entitled “Lower-Cost LiDAR is Key to Self-Driving Future,” Bradley Berman proposes rotary LiDAR sensors as the best choice for autonomous driving. [5] He compares the sensor to a castle built on top of a hill. “The king can see who’s coming from any direction.” Mechanical Components In order for LiDAR to be fully functional and useful in modern automobiles, the mechanical aspect of the sensor must meet high demands. The sensor has to be able to scan the whole image in real-time, therefore needing the mechanical capability of being able to spin so that it can image up to two million data points using its 64 lasers [3]. The Velodyne HDL64E, in particular, has 64 individual lasers to accurately scan and pinpoint different points onto its laser printed image, giving accurate recitations of the situation. The sensor then feeds this wealth of information to the car’s on-board computer. The more information that the car has about its surroundings, the better it can navigate through them. This point-cloud of information generated by the HDL-64E is the first step in the automated driving process, and without these powerful LiDAR sensors, fully autonomous driving would not be possible. Other Options for Data Acquisition Currently, the use of one singular rotary LiDAR sensor is generally accepted as the future of the fully autonomous driving industry, however there are two other main schools of thought for use in the data acquisition; conventional camera systems and flash LiDAR. Conventional camera systems were the first generation of sensors to be used in autonomous 2 Andrew Parker Josh Vinoya The dark circle directly surrounding the vehicle is its blind spot where the sensor cannot see. That is one of the main disadvantages to using a singular sensor located on the car’s roof; it cannot see anything directly beside the car. One potential solution is to use several smaller flash LiDAR sensors in conjunction with the HDL-64E. They would help to fill in the blind spot accompanying a rotary sensor. Consumers will desire an overwhelming sense of safety when first purchasing self-driving vehicles, and the redundancy provided by using additional sensors will provide that peace of mind. Image Computations The LiDAR sensor must be able to analyze its surroundings, much like a human eye surveying the road, and store its 3-D map in its memory for analyzation [7]. Because 3-D mapping of unknown objects cannot be analyzed by the sensor itself, the sensor will identify objects based on preexisting 3-D models of objects set into the computer through algorithms in its code. For example, a tree would be identified by the sensor when it matches the 3-D model with the preset 3-D model coded into the computer [6]. Engineers are also working on “deep learning” neural networks that learn as they drive, which will help to account for the erratic nature of other drivers. The more time those cars spend on the roads, the better they will become at adapting to other car’s behavior and keeping their passengers safe. Next, a preset laser-scanned image is put through a series of modeling techniques that will enhance the computer’s understanding of the situation that it is currently driving in. The modeling technique utilized by the Velodyne HDL-64E is called Two-Level Adaptive Grid Modeling (L2 AGM) [6]. This entails that after the LiDAR detector scans its surrounding and takes the flash image into its memory, it will then separate all of the miniscule image pixels and will classify the background of the image first. This multistep-process will allow the computer to completely digest the information. The background is then put into a two-dimensional Cartesian coordinate plane and is evenly distributed onto the graph as an array of mathematical values representing the background objects [7]. Once the geographical input is set, the system will then take the rest of the laser images as smaller points within the bigger background. This will be used to process and execute the command set for the car to take. Below is an example of the data input that would be fed into the computer system from a single HDL-64E LiDAR sensor. The road surface can be clearly seen, as well as the other cars on the road and any obstacles that the vehicle has to navigate around. This image illustrates just how much data can be quickly gathered using the HDL-64E. Erratic Human Driving The hardest part of programming an autonomous vehicle is accounting for other humans driving erratically. A computer does not know how to react to a driver making a right hand turn from the left hand lane because it defies all logical guidelines. City driving is especially difficult because of the influx of pedestrians, sharp turns, and other vehicles often stuck in a gridlock. Another driver may wait until 100 feet before their turn to get into the proper lane. This leaves very little time for the computer to sense that the other car is shifting lanes and adjust its speed accordingly. Self-driving cars are currently being heavily tested in Pittsburgh because it was deemed one of the most difficult cities to drive in. There, the vehicles would run into many situations in which they would not know how to respond, making it a good city to learn in. Also, LiDAR sensors struggle to drive on bridges due to the lack of background cues. This is one of the problems that engineers are currently working on improving for future generations of autonomous driving. SIGNIFICANCE OF FULLY AUTONOMOUS VEHICLES According to a Lawcore article on car accident statistics, someone dies because of a car accident every 12 minutes and someone else is injured every 14 seconds, with distracted driving being the number one cause of accidents [1]. In 94% of collisions, driver error is the problem [8]. Driving is an extremely serious task; however, many underestimate the danger associated with it because they have driven thousands of miles in the past, and believe themselves to be superior drivers. As phones and computers worm their way deeper and deeper into our lives, thousands of drivers are putting themselves and others at risk every day. Self-driving cars have the potential to drastically reduce the number of traffic fatalities each year by eliminating human error from the equation of driving. A LiDAR sensor in conjunction with an advanced on-board computer system can make tens of thousands of decisions every second and react much faster than a human. So far, in every accident that self-driving cars have been involved in, the crash was the result of another human driver, not the autonomous vehicle. The majority of those crashes were the autonomous vehicle getting rear-ended. In FIGURE 2 [4] Sample Data Point Cloud 3 Andrew Parker Josh Vinoya congestion will cost $192 billion” [9]. With these astounding figures, the ties to economic sustainability also begin to emerge. Since there is such a substantial waste associated with daily drive times, there is a definite economic goal when researching improvements in LiDAR. Companies are willing to spend the time and resources to further this technology because it truly does solve a problem that millions of Americans face every day. addition, every American wastes dozens of hours every year driving. Autonomous vehicles could allow for people to be much more productive behind the wheel. The true significance of fully autonomous driving depends entirely on how deep the implementation becomes. A highway with just one or two self-driving vehicles would improve the safety for those few passengers, as well as any surrounding cars. Imagine for a moment however, a highway completely filled with autonomous vehicles. Vehicles that could potentially communicate with each other via Bluetooth. This is the scenario that has the potential to save thousands of lives every year by making driving safer. This scenario is not in our near future however. There are still millions of miles that autonomous vehicles must drive with technicians behind the wheel, ready to take action, before they become available for commercial use. OTHER APPLICATIONS OF LiDAR The impressive data-gathering power of LiDAR sensors had drawn attention from areas outside of the autonomous driving industry. For example, LiDAR is currently being used by the National Ocean Service to examine and map the surface of the earth [10]. In an article published by the U.S. Department of Commerce entitled “What is LiDAR?”, other applications such as shoreline mapping, hydrodynamic modeling, and coastal vulnerability analysis are explained [10]. They use LiDAR sensors in conjunction with an integrated GPS system to assign a unique 3-D coordinate to each data point collected; latitude, longitude, and elevation. In addition, they can measure the seafloor using bathymetric LiDAR sensors that emit green light to permeate the water. Another important application is the mapping of large scale urban environments. According to an Institute of Electric and Electronics Engineers article entitled “GPS Precision Time Stamping for the HDL-64E LiDAR Sensor and Data Fusion,” efficient mapping of urban areas is possible through the conjoined use of LiDAR sensors and differential GPS systems [7]. After their internal clocks are aligned, a vehicle can drive the GPS and sensors through complicated areas and gather an extremely rich data set from which an incredibly detailed 3-D model of the area can be reconstructed. This would be extremely helpful to city planners, traffic workers, and emergency response teams. Social and Economic Sustainability Often, sustainability is simply taking a step back and trying to see how a concept will interact with the world when put into practice. The idea of sustainability, however, can be viewed from many different angles, as it is such a broad topic. The most areas of sustainability which most readily apply to autonomous driving are social and economic sustainability. Social sustainability can be defined as assisting to maintain or further the wellbeing of society. A product that is socially sustainable would be one that improves the quality of life of those using it. Velodyne’s LiDAR, and autonomous driving in general would aid in improving the quality of life in a multitude of ways. First, as the number of self-driving cars on the road increased, the number of automobile deaths would decrease. This is due to the proven safety record of autonomous vehicles. As computers began to take over the task of driving from humans, driver error could begin to slowly be eradicated as a cause of crashes. It is impossible to think that there will ever exist a world with no automobile fatalities, however the current numbers are likely to see a harsh decline following the widespread implementation of self-driving vehicles. In addition, autonomous vehicles would improve the quality of life for millions by reducing the stress and time wasted stuck in traffic. A thirty-minute commute to work may seem insignificant, however that quickly adds up to 250 hours a year. (Note two weeks are subtracted due to vacation time, illness etc.) 𝟏 𝟐 ETHICAL IMPLICATIONS The ethical dilemmas faced by the autonomous driving industry are a very controversial topic. In this section, we will propose a scenario in which the car is forced to make a decision that will have a significant impact on the lives of not only its passengers, but others as well. We will then discuss the different schools of thought on what the car should do in that situation, as well as who would be responsible in the event of the accident. Before the widespread implementation of fully self-driving cars, a standard set of ethical guidelines must be agreed upon. In a TED-Ed talk on “The Ethical Dilemma of SelfDriving Cars”, Patrick Lin proposes a scenario in which an automated vehicle is driving on the highway [11]. The car is boxed in on all sides. Suddenly, a large box falls off of the truck in front of it and the car does not have time to stop, so the car must make a decision; swerve left into a SUV, or 𝒅𝒂𝒚𝒔 𝒉𝒐𝒖𝒓 × 𝟐 𝒕𝒓𝒊𝒑𝒔 × 𝟓 𝒘𝒆𝒆𝒌 × 𝟓𝟎 𝒘𝒆𝒆𝒌𝒔 = 𝟐𝟓𝟎 𝒉𝒐𝒖𝒓𝒔 𝒅𝒂𝒚 𝒚𝒆𝒂𝒓 𝒚𝒆𝒂𝒓 [Eq. 2] Adults who work for 40+ years of their life are throwing away weeks and weeks of time that could be better spent working, learning, or just relaxing. The problem isn’t getting any better either. An ABC news article predicts that by 2020, “the total nationwide delay time will grow to 8.3 billion hours -- an increase of 1.4 billion hours in just 5 years -- and 4 Andrew Parker Josh Vinoya swerve right into a motorcycle. If the car swerves into the motorcycle, it will protect the passenger of the car but most likely kill the defenseless cyclist. If it swerves left, the collision will be less severe, however a SUV may have multiple passengers, putting more lives at risk. Finally, it could not swerve at all and directly collide with the box, potentially sacrificing the passenger’s life, but not putting any others in harm’s way [8]. Patrick points out that if a human were driving the car, whichever way they swerved would be accepted as just a split decision, and they would not be blamed for choosing one over the other. They had no time to think about it; their choice was just an instantaneous, panicked reaction [11]. This is a strong contrast with a decision that would be made prior to the event. In autonomous driving, a programmer must tell the computer that given this specific set of inputs, it should do a certain output. The result of who lives and who dies could be decided months, or even years beforehand by how the computer system was programmed to respond. This is where the true ethical dilemmas of computer-assisted driving arise. Autonomous vehicles would make the roads overall safer, however those who are injured would be chosen beforehand. The Talk concludes by stating that the autonomous driving system is working as a “targeting algorithm” [11]. It is favoring certain types of objects to crash into over others. Should a car swerve into a motorcyclist who is wearing a helmet, or one with no helmet? The one with the helmet is more likely to survive, however the algorithm is punishing the cyclist for being more responsible. This, and many other complicated situations arise when discussing how to program computers for use in autonomous driving. The programmers must compile a list of precedence and definitively state for example that a 20% chance of saving the life of person X is more important than a 60% chance of injuring person Y. Also, should an autonomous vehicle take the life of its passengers as more important if it knows information about them? For example, a mother driving five young children to soccer practice versus a senior citizen driving by themselves. Then the question arises of who should make these decisions. Even seemingly simple guidelines such as “minimize harm” break down quickly when these complex situations are proposed [8]. Currently, we as a society have no definitive answer. As technology continues to accelerate at unprecedented rates, ethics will become more and more important in how we navigate these uncharted waters. expensive than most cars themselves, and thus very impractical for commercial use. Dr Wolfgang Juchmann, Velodyne’s director of sales and marketing, believes that LiDAR will follow a similar downward trend in price to radar [5]. “If you look at 10 or so years ago, radar sensors were $10,000. I’m sure the first people said, ‘radar? Putting six of those on every car is completely unbelievable. But everybody saw the benefits. The market got there, and the price came down” [5]. The current limiting reactant in terms of the cost is the labor required to build the sensors. There is nothing about the materials that will keep the price above acceptable consumer levels. There is no excess of raw materials, or hazardous components associated with the construction of the sensors. Thus, the worldwide implementation of LiDAR would not put an excessive drain on the environment. As market demand continues to rise as self-driving cars become more popular, the cost will decline as well. In addition, this problem is not unique to LiDAR. Every technology from the combustion engine to the light bulb has a period where it is at first impractical for widespread use. As years go by and new advancements get made, the price of LiDAR will continue to fall, so the question is not IF the technology will be made available for commercial use, but WHEN. Also, the sensor needs to get smaller. The HDL-64E, while powerful, is not very aesthetically pleasing. Consumers may be much more willing to purchase a fully autonomous vehicle if the sensor was smaller and less bulky. The high cost and the bulky nature of the HDL-64E are the two main challenges facing the autonomous driving industry currently. THE FUTURE OF DRIVING The substantial data-gathering power of LiDAR sensors has propelled them to the forefront of technology in many disciplines. Velodyne’s model HDL-64E rotary LiDAR sensor is currently used for fully autonomous driving applications. The rotary head, in conjunction with the 64 independent channels allow for an extremely dense 3-D point cloud of information to be gathered, and then used in the car’s computer system. If implemented on a large scale, fully autonomous vehicles have the potential to save thousands of lives every year. Finally, accidents, though uncommon, will still occur, and the actions to be undertaken, as well as who is responsible for them is still a topic of debate within our society. SOURCES WHAT’S NEXT FOR LiDAR [1] “Car Accident Statistics.” Lawcore.com. 2016. Accessed 1.8.2017. http://www.lawcore.com/caraccident/statistics.html [2] C. Parish. “Laser vision for self-driving cars.” Automotive Industries. 12.2016. Accessed 1.8.2017. http://web.a.ebscohost.com/bsi/detail/detail?vid=5&sid=5c69 8436-5603-4251-8880- Every day, engineers are learning more about how to improve LiDAR systems and make them safer for use in fully autonomous vehicles. While they are currently very technologically advanced, some improvements still need to be made before their widespread implementation. In order for LiDAR to be put into use in fully autonomous, commercial vehicles, the cost of the sensor needs to come down. Right now, the HDL-64E retails for $75,000 [5]. This is more 5 Andrew Parker Josh Vinoya 763dfb7150b2%40sessionmgr4010&hid=4201&bdata=JnNp dGU9YnNpLWxpdmU%3d#AN=120239294&db=bth [3] “Velodyne LiDAR HDL-64E High Definition Real-Time 3D LiDAR.” Velodyne LiDar. 2016. Accessed 1.9.2017. http://velodynelidar.com/docs/datasheet/63-9194%20RevE_HDL-64E_S3_Spec%20Sheet_Web.pdf [4] T. Deyle. “Velodyne HDL-64E Laser Rangefinder PseudoDisassembled.” Hizook Robotics News for Academics & Professionals. 1.4.2017. Accessed 2.25.2017. http://www.hizook.com/blog/2009/01/04/velodyne-hdl-64elaser-rangefinder-lidar-pseudo-disassembled [5] B. Berman. “Lower-cost LiDAR is key to self-driving future.” Automotive. 11.2.2015. Accessed 1.9.2017. http://articles.sae.org/13899/ [6] A. Borcs. “On board 3D object perception in dynamic urban areas.” IEEE Xplore Digital Library. 2.12.2013. Accessed 1.8.2017. ieeexplore.ieee.org.pitt.idm.oclc.org/document/6719301/ [7] A. Moreno. “GPS Precision time stamping for the HDL64E LiDAR sensor and data fusion.” IEEE Xplore Digital Library. 19.11.2012. Accessed 1.8.2017. ieeexplore.ieee.org.pitt.idm.oclc.org/document/6524554/ [8] D. Muller. “The Real Moral Dilemma of Self-Driving Cars.” Veritasium. 1.19.2017. Accessed 1.25.2017. https://www.youtube.com/watch?v=WBjY3QGNdAw [9] E. Dooley. “Here’s How Much Time Americans Waste in Traffic.” ABC News. 8.26.2015. Accessed 3.29.2017. http://abcnews.go.com/US/time-americans-wastetraffic/story?id=33313765 [10] “What is LiDAR?” National Ocean Service. 5.29.2015. Accessed 1.9.2017. http://oceanservice.noaa.gov/facts/lidar.html [11] P. Lin. “The ethical dilemma of self-driving cars.” TED Ed. Accessed 1.25.2017. http://ed.ted.com/lessons/the-ethicaldilemma-of-self-driving-cars-patrick-lin#watch [12] M. Staff. “Ford, Baidu invest $150 million for LiDAR sensors to improve self-driving cars.” Christian Science Monitor. 8.16.2016. Accessed 1.9.2017. http://web.b.ebscohost.com/ehost/detail/detail?sid=bef5b6ada94f-45ef-950dff6626287404%40sessionmgr106&vid=0&hid=101&bdata=J kF1dGhUeXBlPWlwLHVpZCZzY29wZT1zaXRl#AN=1174 75944&db=aph ACKNOWLEDGMENTS We would like to take the time to thank the tireless efforts of our both our conference chair and co-chair. Their dedication and passion for engineering, as well as for helping others helped our paper on a grand scale. We would also like to thank the writing center and library helpers for their detailed explanation of the assignment set forth before us, as well as for answering questions as they arose throughout the process. Without the aforementioned persons, this paper would be lacking in both quality and direction. 6
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