Stewart rigs operate Doc Ock's tentacle
The tentacles of the octopus are essentially long, continuous muscles, much like your tongue. This anatomy gives octopuses incredible dexterity, but it is very difficult to replicate in robots. Artificial "muscular" fiber is not yet very practical, which is why roboticists are turning to more conventional means of actuation. Cable-driven tentacles are popular, but they require many powerful cable motors. For his new project, James Bruton took a different approach and used Stewart rigs.
Stewart rigs are quite common in industrial settings, as they can be operated with hydraulic pistons that support a lot of weight. Six linear actuators arranged between two plates allow the second plate to move at any angle relative to the first plate, the exact angle depending on the actual lengths of the actuators. By chaining multiple Stewart rigs together, Bruton created a tentacle-like structure with complete freedom in every joint.
The current prototype only has three Stewart platforms, but these are sufficient to demonstrate the concept. Bruton used servos instead of linear actuators to save costs. An Arduino Mega 2560 board controls these: a total of 18 servo motors. The entire structure is made of 3D printed parts.
But expanding this design to a full Doc Ock tentacle (let alone four of them) would present challenges. As with any robot arm, motors closer to the base experience more load as the arm's weight and length increase. These should probably be replaced with beefier models. And with six servos for each joint, even an Arduino Mega 2560 would quickly run out of pins. This could however be solved by using multiple Arduino boards or an IO expander.
The tentacles of the octopus are essentially long, continuous muscles, much like your tongue. This anatomy gives octopuses incredible dexterity, but it is very difficult to replicate in robots. Artificial "muscular" fiber is not yet very practical, which is why roboticists are turning to more conventional means of actuation. Cable-driven tentacles are popular, but they require many powerful cable motors. For his new project, James Bruton took a different approach and used Stewart rigs.
Stewart rigs are quite common in industrial settings, as they can be operated with hydraulic pistons that support a lot of weight. Six linear actuators arranged between two plates allow the second plate to move at any angle relative to the first plate, the exact angle depending on the actual lengths of the actuators. By chaining multiple Stewart rigs together, Bruton created a tentacle-like structure with complete freedom in every joint.
The current prototype only has three Stewart platforms, but these are sufficient to demonstrate the concept. Bruton used servos instead of linear actuators to save costs. An Arduino Mega 2560 board controls these: a total of 18 servo motors. The entire structure is made of 3D printed parts.
But expanding this design to a full Doc Ock tentacle (let alone four of them) would present challenges. As with any robot arm, motors closer to the base experience more load as the arm's weight and length increase. These should probably be replaced with beefier models. And with six servos for each joint, even an Arduino Mega 2560 would quickly run out of pins. This could however be solved by using multiple Arduino boards or an IO expander.
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