Spatial measurement system for agricultural applications

A system for measuring spatial relationships between objects comprising:

• a vertical centerline;
• a frame;
• a reel rotatably mounted to the frame;
• a length of a flexible measuring line wound around the reel, the reel rotatable in opposing direction to retrieve the measuring line or dispense the measuring line on demand;
• a measurement assembly comprising at least one fixed pulley and an encoder comprising an encoder shaft, the measuring line wrapped around the at least one fixed pulley and encoder shaft in operable engagement therewith;
• and
• a movable self-adjusting tension arm assembly arranged between the reel and measurement assembly in a measuring line routing path, the tension arm assembly comprising an inboard arm pivotably mounted to the frame and an outboard arm pivotably coupled to inboard arm at an articulated joint and movable relative thereto;
• the tension arm assembly comprising a translatable pulley mounted to and movable with the outboard arm;
• a fixed tension pulley cooperating with the tension arm assembly and mounted to the frame;
• a first spring biasing the tension arm assembly in a direction away from the encoder;
• the measuring line extending from the at least one fixed pulley of the measurement assembly to the translatable pulley or the fixed tension pulley;
• wherein the tension arm assembly is movable in a plurality of positions dependent upon variations in tension of the measuring line when the measuring line is retrieved by the reel.

A method for maintaining tension in a distance measuring device, the method comprising:

• providing a measurement device comprising a frame including a rotatable reel around which a length of a measuring line is wound, a motor comprising a motor gear selectively coupleable to a reel gear for rotating the reel, an encoder comprising an encoder shaft, and a pivotably movable spring-biased tension arm assembly;
• routing the measuring line in order from the reel and operably engaging a translatable pulley mounted to the tension arm assembly, a fixed tension pulley mounted to the frame, and the encoder shaft;
• moving the measurement device in a first linear direction;
• applying a first tension force to the measuring line;
• unwinding measuring line from the reel which rotates in a first feed direction;
• rotating the tension arm assembly in a first direction towards the encoder in response to the first tension force;
• moving the measurement device in a second linear direction opposite to the first linear direction which decreases the first tension force;
• automatically rotating the tension arm assembly in a second direction away from the encoder via spring force in response to decreasing the first level of tension;
• coupling the motor gear to the reel gear;
• and
• rotating the reel in a second rewind direction via operation of the motor to retrieve measuring line.

A method for maintaining tension in a distance measuring device, the method comprising:

• providing a measurement device including a rotatable reel around which a length of a measuring line is wound, a motor comprising a motor gear selectively coupleable to a reel gear for rotating the reel, an encoder comprising an encoder shaft operably engaging the measuring line, and a pivotably movable spring-biased tension arm assembly operably engaging the measuring line;
• pulling a length of measuring line from the reel, wherein a first tension force is created in the measuring line acting in a line feed direction;
• forming slack in the measuring line which decreases the first tension force;
• rotating the tension arm assembly in a line retract direction opposite to the line feed direction;
• the tension arm assembly creating a second tension force in the measuring line;
• activating a motor operably coupled to the reel via rotating the tension arm assembly;
• and
• rewinding measuring line back onto the reel via motor power.