Abstract: This disclosure describes a ground station configured to facilitate the delivery of payloads using unmanned aerial vehicle (UAV). The ground station includes multiple sensors that allow for autonomous operation of the ground station as part of a larger payload transportation system. The sensors are configured to confirm loading of payloads onto a UAV, checking a status and safety of the drone and clearing an area surrounding the ground station prior to takeoff and/or landing operations of the UAV.

Abstract: Methods and apparatus are described for a two-axis tracking mechanism for a concentrated photovoltaic system. Two or more components forming the support structure of the two-axis tracker mechanism, which are assembled in the field and manufactured to allow one or more lasers to align the support structure of the two-axis tracker mechanism in three dimensions, vertical (X) dimension, horizontal (Y) dimension, and diagonal (Z) dimension, at a site where the concentrated photovoltaic system is to be installed. Adjustable leveling mechanisms are built into the two or more components forming the support structure.

Abstract: Methods and apparatus are described for a two axis tracking mechanism for a concentrated photovoltaic system. Two or more paddle structures containing multiple CPV modules are installed onto each tilt axle on the common roll axle as part of the two-axis tracking mechanism's solar array. The two or more paddle structures couple across the common roll axle on that tilt axle. The common roll axle and each paddle assembly are manufactured in simple modular sections that assemble easily in the field while maintaining the alignment of the tracker assembly.

Abstract: Methods and apparatus are described for a two axis tracking mechanism for a concentrated photovoltaic system. Two or more paddle structures containing multiple CPV modules are installed onto each tilt axle on the common roll axle as part of the two-axis tracking mechanism's solar array. The two or more paddle structures couple across the common roll axle on that tilt axle. The common roll axle and each paddle assembly are manufactured in simple modular sections that assemble easily in the field while maintaining the alignment of the tracker assembly.

Abstract: Methods and apparatus are described for a two axis tracking mechanism for a concentrated photovoltaic system. Two or more components forming the support structure of the two-axis tracker mechanism, which are assembled in the field and are manufactured to allow one or more lasers to align the support structure of the two-axis tracker mechanism in three dimensions vertical (X) dimension, horizontal (Y) dimension, and diagonal (Z) dimension at a site where the concentrated photovoltaic system is to be installed. Adjustable leveling mechanisms are built into the two or more components forming the support structure.

Abstract: A method (51) for measuring the mass of an object such as a letter (10) in motion. An apparatus (12) for carrying out the present invention includes a pair of rollers (16, 18) through which a letter passes. One of the rollers (16) is driven by a motor (20) which has an associated encoder (22) to give motor positional information to a controller (24). In a method of the present invention the controller generates a ramping torque signal (44) which is provided to the motor. A friction correction curve (40) is generated and applied to the torque signal, and an average torque value (C) is determined. From the positional information provided by the encoder, acceleration (50) is derived and an inertia value is obtained by dividing the average torque (C) by the acceleration. Prior to obtaining an inertia value with a letter, an initial inertia value is obtained without a letter to get a base inertia. The base inertia is subtracted from the measured inertia with a letter to get a difference ?I.

Abstract: A method (51) for measuring the mass of an object such as a letter (10) in motion. An apparatus (12) for carrying out the present invention includes a pair of rollers (16, 18) through which a letter passes. One of the rollers (16) is driven by a motor (20) which has an associated encoder (22) to give motor positional information to a controller (24). In a method of the present invention the controller generates a ramping torque signal (44) which is provided to the motor. A friction correction curve (40) is generated and applied to the torque signal, and an average torque value (C) is determined. From the positional information provided by the encoder, acceleration (50) is derived and an inertia value is obtained by dividing the average torque (C) by the acceleration. Prior to obtaining an inertia value with a letter, an initial inertia value is obtained without a letter to get a base inertia. The base inertia is subtracted from the measured inertia with a letter to get a difference ?l.