Spiderbot: Large Scale 3D printer
The SpiderBot is a cable-suspended robotic gantry system that provides an easily deployable platform from which to print large structures. The body composed of a deposition nozzle, a reservoir of material, and parallel winching electric motors. Cables from the robot are connected to stable points high in the environment, such as large trees or buildings. This actuation arrangement is capable of moving large distances without the need for more conventional linear guides, much like a spider does. The system is easy to set up for mobile projects, and will afford sufficient printing resolution and build volume. Expanding foam can be deposited to create a building-scale printed object rapidly. Another material type of interest is the extrusion or spinning of tension elements, like rope or cable. With tension elements, unique structures such as bridges or webs can be wrapped, woven, or strung around environmental features or previously printed materials.
Full description:
Using the “spiderbot” platform as a positioning system, a variety of extruded materials can be utilized for structural elements, both in tension and compression. One promising system is urethane foam deposition. These fast curing foams offer numerous benefits for printing over directly printing concrete, for instance in cure time, weight, and layer adhesion. With a cure time around 30 seconds and a density of 1.75 lb/ft3, urethane foam can be deposited to create a building-scale printed object rapidly. Then, using conventional concrete, the urethane mold can be filled to create an insulated structural wall. This approach offers the benefits of speed, customizability, and low-cost for construction of buildings. Another material type of interest is the extrusion or spinning of tension elements (rope or cable). With tension elements, unique structures (like bridges) can be wrapped, woven or strung around environmental features or previously printed materials.
Normally, structures are built by the aid of one or several large cranes which lift and hoist building elements into place for fastening to the groundwork. As the current trend in manufacturing moves to automation, cranes would prove to be poor 3d printing platforms due to the highly unconstrained motion of the swinging cable and a limited range of motion
The spiderbot provides a more stable platform for 3d positioning of objects and improved range and lifting capacity due to the assembled parallel actuators. If all winching motors are stored onboard the device, it will also be capable of very fast deployment, in a matter of minutes, which may be crucial for other uses such as 3d printing structures for disaster relief and lifting/removing rubble.
The primary intended use for this device is a quickly deployable, large scale positioning system for building construction. Building contractors may use this device as a CNC crane-for material deposition, or as a formative tool. Relief efforts may find this platform useful for quickly fabricating small shelters or for clearing and removing fallen structural elements.
Full description:
Using the “spiderbot” platform as a positioning system, a variety of extruded materials can be utilized for structural elements, both in tension and compression. One promising system is urethane foam deposition. These fast curing foams offer numerous benefits for printing over directly printing concrete, for instance in cure time, weight, and layer adhesion. With a cure time around 30 seconds and a density of 1.75 lb/ft3, urethane foam can be deposited to create a building-scale printed object rapidly. Then, using conventional concrete, the urethane mold can be filled to create an insulated structural wall. This approach offers the benefits of speed, customizability, and low-cost for construction of buildings. Another material type of interest is the extrusion or spinning of tension elements (rope or cable). With tension elements, unique structures (like bridges) can be wrapped, woven or strung around environmental features or previously printed materials.
Normally, structures are built by the aid of one or several large cranes which lift and hoist building elements into place for fastening to the groundwork. As the current trend in manufacturing moves to automation, cranes would prove to be poor 3d printing platforms due to the highly unconstrained motion of the swinging cable and a limited range of motion
The spiderbot provides a more stable platform for 3d positioning of objects and improved range and lifting capacity due to the assembled parallel actuators. If all winching motors are stored onboard the device, it will also be capable of very fast deployment, in a matter of minutes, which may be crucial for other uses such as 3d printing structures for disaster relief and lifting/removing rubble.
The primary intended use for this device is a quickly deployable, large scale positioning system for building construction. Building contractors may use this device as a CNC crane-for material deposition, or as a formative tool. Relief efforts may find this platform useful for quickly fabricating small shelters or for clearing and removing fallen structural elements.
Current prototype:
Below is a short video of the first prototype of the concept. It was made from four ATV winches (3,000 lbs of towing each), several sealed batteries and some radio control rigged up.
As you might notice in the video, the platform probably isn't stable enough by itself for direct printing. The support cables are only in tension from the weight of the robot pulling them taught, so when the platform moves, it sways and inch or two back and forth as it's moving (less if it moves slowly). Top speed is roughly 6-8 in/s depending on loading.
How can we make it better?
Future versions of this system would need to include an active/passive, gyroscopic or mass-spring-damper, "steady-cam" type of system coupled to the material depositor to dampen out vibrations and negate oscillations of the platform. Such a system is used in the most famous commercial application of this concept, the "sky-cam".
Due to the speed of these motors and comparative the mass of the system it is unlikely that shaped drive inputs (powered settling) to the motors would sufficiently increase settling time of the robot. If faster, off-board motors were used, actively settling oscillations through the drive cables may be possible.
Other examples of cable suspended robotics often include more cables coming down from the suspended robot to the ground. These cables are then used, instead of a gravity bias, to pull all cables in tension and make the platform very stable. Such an arrangement may be possible for this concept, but would require occasional re-fixturing of these lower cables as the structure is built so they would not physically interfere with material deposition.
Below is a short video of the first prototype of the concept. It was made from four ATV winches (3,000 lbs of towing each), several sealed batteries and some radio control rigged up.
As you might notice in the video, the platform probably isn't stable enough by itself for direct printing. The support cables are only in tension from the weight of the robot pulling them taught, so when the platform moves, it sways and inch or two back and forth as it's moving (less if it moves slowly). Top speed is roughly 6-8 in/s depending on loading.
How can we make it better?
Future versions of this system would need to include an active/passive, gyroscopic or mass-spring-damper, "steady-cam" type of system coupled to the material depositor to dampen out vibrations and negate oscillations of the platform. Such a system is used in the most famous commercial application of this concept, the "sky-cam".
Due to the speed of these motors and comparative the mass of the system it is unlikely that shaped drive inputs (powered settling) to the motors would sufficiently increase settling time of the robot. If faster, off-board motors were used, actively settling oscillations through the drive cables may be possible.
Other examples of cable suspended robotics often include more cables coming down from the suspended robot to the ground. These cables are then used, instead of a gravity bias, to pull all cables in tension and make the platform very stable. Such an arrangement may be possible for this concept, but would require occasional re-fixturing of these lower cables as the structure is built so they would not physically interfere with material deposition.
