Long-range laser tracking system

Tampere University Foundation sr (Tampere University) is publishing a direct award of contract for Long-range laser tracking system. Laser tracker system is needed to be capable of continuous measurement of six degrees of freedom, i.e., position and orientation at 1000 Hz measurement rate.

BACKGROUND INFO Automation and robotics plays an increasingly important role in technology and economy. Tampere University (TAU) conducts robotics education and research in the Faculty of Engineering and Natural Sciences., Unit of Automation Technology and Mechanical Engineering. TAU has a world-class research infrastructure to conduct robotics research, both in outdoor-focused non-road mobile machines and indoor-focused industrial collaborative robotics, in applications such as simultaneous localization and mapping and vision-based position and orientation estimation algorithms. TAU also offers a Master of Science education programme in Robotics since 2023. TAU MobileLab (https://research.tuni.fi/iha/facilities/mobile-laboratory/) provides excellent facilities for field off-road machinery and robotics research, as the campus area includes a test ground and has over 10 instrumented mobile machines. The closed 4000 m² test ground has a working area for excavating, different surfaces ranging from gravel to asphalt, and a hill with three different slopes ranging up to about 18 degrees. TAU RoboLab (https://research.tuni.fi/robolabtampere) offers a place for students to work with robotic equipment and experiment without major restrictions. Robots and related technology are for example industrial manipulators (Kuka Iiwa, Flexfellow, Universal robots, Franka Panda, PRob), mobile robots (turtlebot, MiR100, in-house developed robot) and a multitude of sensors (2D/3D ToF cameras, LiDAR, GNSS, IMU, etc.). NEED In the research of robotics and intelligent heavy machines, there is a need to have a ground-truth measurement system that can act as an independent measurement of position and orientation of any moving object at sub-millimeter accuracy. This external measurement system can be used to benchmark, calibrate and verify accuracy of various pose estimation and localization algorithms that can be based on various types of sensor data (e.g., LIDAR, GNSS, camera and inertial measurement units). The need to measure both position and orientation of large-scale machines restricts contracting authority’s need on laser tracker systems that offer wireless targets. The target used must not require external cabling for power or communication but must be wireless (battery-powered), because running cables to the ends of large booms is not always possible or practical in measurement setups. Moreover, the spatial measurement provided by the laser tracker needs to be temporally synchronized and timestamped relative to other sensor measurements of TAU robotic research platforms such as vehicles using standardized automation fieldbus technology. Tampere University does not have a system that is suitable to be used in outdoor conditions for the purposes of intelligent heavy machines research and that is capable of continuous (min. 100 Hz) position and orientation measurement of robotic manipulators and mobile robots. Therefore, to increase the quality and effectiveness of the conducted scientific research results and lower the time spent for pose accuracy verification methods, a laser tracker system that is capable of continuous measurement of six degrees of freedom, i.e., position and orientation at 1000 Hz measurement rate, is needed to complement the existing research infrastructure. MARKET ANALYSIS AND CONCLUSION FOR DIRECT AWARD Market research has been conducted by searching information about commercially available laser tracker systems capable of measuring position and orientation at a sample rate of 1000 Hz. The requirements from the previous section ‘Needs’ can be summarized as follows: Requirement 1: The laser tracker and target shall be capable of simultaneous measurement of position and orientation, shall be wireless/cordless and have the capability to be attached to robot end-effector without external cabling. Requirement 2: The laser tracker shall have a deterministic time synchronization capability with other measurement systems, either in the form of an industrial Ethernet based fieldbus connection (e.g. EtherCAT) or IEEE 1588 Precision Time Protocol. The laser tracker's control system must have an automation fieldbus interface, allowing the laser tracker to integrate into the research vehicle's sensor network and provide temporally synchronized data for other measurements on the research platform (e.g., angle encoders, machine vision) through timestamping. Due to its non-deterministic delays, the CAN bus is not suitable for this purpose; instead, the fieldbus must be based on modern industrial Ethernet-based fieldbus (e.g., EtherCAT). Additionally, the visibility of the target to the laser tracker must be as good as possible, to not cause discontinuities to the data due to loss of direct line of sight to the target, and the laser tracker and target should be suitable to be used in outdoor conditions with proper IP rating. These requirements listed above direct the procurement towards the commercially available laser tracker Leica AT960-LR, sold by Hexagon Metrology Nordic AB / Leica Geosystems. Following features are to be taken into consideration: - Leica AT960-LR provides an industrial Ethernet fieldbus interface (EtherCAT), enabling synchronization of measurement data with other automation fieldbus-based sensor measurements and allowing straightforward integration to contracting authority’s research vehicles. - Leica T-Probe wireless target offers the best visibility compared to other alternatives listed in the market research. - Leica AT960-LR has the best ingress protection rating (IP54), making is most suitable to outdoor use compared to other alternatives listed in the market research. Inquiries were made to the resellers of two other manufacturers to find if they offer products with similar features. In comparison to the abovementioned requirements, features were found to be lacking in laser tracker systems from other manufacturers.