The on board surveyor

Transcription

1 The on board surveyor A PPK solution for drone-mapping

2 Introduction DROBIT is a high precision positioning system created for drone-based photogrammetry. Its working principle is differential correction of GNSS kinematic trajectories. DROBIT has been designed to be on board of an aircraft solving continuously the camera center position and attitude and logging precise time marks for shutter actuations. The system allows to attribute geo-coordinates to each photo center point with centimeter level accuracy, and this consequently makes possible to perform photogrammetric surveys with no need for ground control points. The final product typical accuracy is 3cm. DROBIT is not just a device, but a turn-key geomatic solution composed of hardware, software and methods in tight integration. It has been designed by a team composed of engineers in Surveying, Photogrammetry, Computers, Electronics and Telecomms. Main advantages Speed up survey operations: The fieldworks involved on drone mapping projects are limited to the time it takes to deploy the UAV and fly a preprogrammed mission. No need for spreading and surveying targets any more. Lower the cost of mapping: Time is money. DROBIT will not only reduce time on site but also turns the field mission into a one man operation in most cases. Having high precision photo locations also shortens dramatically the computer process time, because it eliminates the need for marking CGPs on all images and therefore allows the full automation of the photogrammetric workflow. Safety is first. Dangerous areas are not void for drone-mapping anymore because no one needs to enter. Are there lions there? Could this stockpile collapse? Do you need to map the mine field? OK no problem. Difficulties for accessing by ground to the area of interest will not be an issue any more. DROBIT makes them irrelevant. Accuracy improvement. It is commonly accepted that for geo-referencing of a set of aerial images accurately, ground control measurement is required. Hence a good instrument and the right methods to survey a well distributed collection of ground targets is mandatory. This is generally true but is not the only way to go as DROBIT proves. The direct reference by camera centers forming a uniform grid always gives the most robust and populated network of 2

3 positional constraints. The even distribution of known points enables homogeneous accuracy across the entire mapping area. Hardware In physical terms, DROBIT is a small footprint electronic device boasting a powerfull CPU integrated with high quality geomatic sensors in barely 50 grams. DROBIT HW not only interfaces with most types of cameras to acquire precise position and orientation of itself, it does much more. It can control camera s settings, download images, automatically write geotags and can even trigger the camera autonomously. The IMU integrated in the DROBIT board allows it to solve dynamically the camera center point by considering the offset between the same and the GNSS antenna phase center. A threedimensional vector whose components are varying constantly as drone frame attitude changes. This feature puts DROBIT system ahead of its competitors. DROBIT allows the operator a high level of functionality related with planning, acquisition and postprocessing of photogrammetry works. And those functions will expand with every firmware upgrade we provide in the future! DROBIT SYSTEM COMPONENTS. Rover module: Designed to be mounted on board of the vehicle and presented as an OEM board that can be bundled with different mounting parts kits to ease the integration. It comes with a low weight active antenna that should be mounted conveniently in the upper part of the aircraft frame. The on board module is complemented by accessories for interfacing the camera trigger by wire with different plugs and a small device that allows to detect the shutter actuation instant by sniffing the flash firing signal through the hotshoe port. 3

4 Base module: Composed of similar parts as the rover module but enclosed in an appropriate housing for the electronics and battery. The enclosure has a ⅝ thread for mounting it on standard surveying tripod or pole. The base module can be replaced by any survey grade GPS receiver capable for output RINEX data at 5hz or higher frequency. (DROBIT reaches up to 20hz raw output) Both modules are operated by means of one single button and provide a simple interface formed of four status leds. In addition they can be accessed and configured by wireless connection from a computer. Once the module is powered, at the press of a button it begins to record position and attitude and to monitor the payload actuations. DROBIT PPK. Is the software tool we have created to ease the post-process of the logs and photo files. Drag your cards folders onto the software main window and all calculations will be carried out almost without user interaction. At the end a handful of files will be created including a quality report, a kml file with a graph of the flight to be visualized in Google Earth, and a list of photo names with their corresponding coordinates and estimation of accuracy. Technical specifications. ELECTRICAL INTERFACES POWER TRIG IN TRIG OUT & SYNC 6V to 12V Interface for input trigger commands from external hardware (Autopilot, etc) Contact closure to GND TTL 3.3V Trigger out command to Camera (both contact closure to GND or PWM) SYNC In from camera for precise geotagging TTL 3.3V Used with proprietary DROBIT HotShoe UART USB TTL Uart for future expansions like RTK Radios USB Click Mate connector for OEMs 4

5 Physical Board Size 71.1mm x 45.7mm x 11 mm Board Weight 48g (excluding housing, mounting/damping parts, batteries and antenna) CPU AND STORAGE DROBIT mainboard has a Dual Core 500Mhz Intel Edison built-in. SoC 22 nm Intel SoC that includes a dual-core, dual-threaded Intel Atom CPU at 500 MHz and a 32-bit Intel Quark microcontroller at 100 MHz RAM 1 GB LPDDR3 POP memory (2 channel 800MT/sec) Flash storage 4 GB emmc (v4.51 spec) WiFi Broadcom* a/b/g/n; Dual-band (2.4 and 5 GHz) Bluetooth Bluetooth 4.0 External SDCard for storage expansion GNSS RECEIVER DROBIT mainboard is mated with a Comnav K501G GPS/GLONASS L1+L2 Receiver Signal Tracking Channels 120 GPS L1 C/A code,l1/l2 P code GLONASS L1,L2 SBAS WAAS, EGNOS, MSAS,GAGAN Performance Specifications Cold start <50s Warm start <45s Hot start < 15s Signal reacquisition <2s Velocity Accuracy 0.03m/s Acceleration 4g 5

6 Overload 15g Positioning Specifications Post Processing Static 2.5 mm + 1 ppm Horizontal 5 mm + 1 ppm Vertical Single Baseline RTK(<20km) 10 mm + 1 ppm Horizontal 20 mm + 1 ppm Vertical DGPS 0.5 m 3D RMS SBAS 1 m 3D RMS Standalone Positioning Accuracy 1.5 m 3D RMS Time Precision GPS+GLONASS 20ns Communications Communication port 3 LV-TTL RS232 Ports, Baud rates up to 921,600 bps Positioning data outputs 1 Hz,5 Hz & 10Hz Raw data outputs 1Hz, 5Hz, 10Hz & 20Hz PPS 1 Pulse Per Second Output Event marker Event marker input Indicating light 3 LEDs (indicating Power, Satellite Tracking and Differential Data) Data Format Correction data I/O RTCM 2.x, 3.x. CMR (GPS only),cmr + (GPS only) Position data outputs ASCII: NMEA-0183 GSV, RMC, HDT, VHD, GGA, GSA, ZDA, VTG, GST, PJK, PTNL Extended NMEA-0183 BDGGA, GPNTR, GPCDT, GPHPR ComNav Binary (compatible with major brands) 6

7 INERTIAL MEASUREMENT UNIT DROBIT is equipped with an onboard IMU that provides important orientation information that is mandatory in order to calculate coordinates corrected to camera center. IMU values are used to provide increased position accuracy and faster fusion position estimations. The IMU is a STMicroelectronics LSM9D with accelerometer data acquisition rate up to 1600 Hz. Main features: 3 acceleration channels, 3 angular rate channels, 3 magnetic field channels ±2/±4/±6/±8/±16 g linear acceleration full scale ±2/±4/±8/±12 gauss magnetic full scale ±245/±500/±2000 dps angular rate full scale 16-bit data output SPI / I2C serial interfaces PRICING Disclaimer: The following pricing scheme might be subject to changes according to options for mounting, wiring and needs for customized parts required for integration. VALUE ADDED TAX is excluded and will be 21% if applies. DROBIT HW rover module 4000,00 DROBIT HW base module 4500,00 Custom Integration service available If you have further questions, please request contact us at info@drobit.es 7