This paper surveys modular robot systems, which consist of multiple modules and aim to create versatile, robust, and low cost systems. The modularity allows these robots to self-assemble, self-reconfigure, self-repair, and self-replicate.
Versatility is the capability of the modular robotic system to form a number of different shapes; each with big numbers of degrees of freedom (DOF). Robustness comes from redundancy and self-repair. Low cost can be achieved through rapid prototyping equipment techniques; such as 3D printing, that can build any object by laying down successive layers of material.
The natural construction of complex multi-unit system using simple units governed by a set of rules.
The ability to form a larger stronger robot using smaller modules allows self-assembled robots to perform tasks in remote and hazardous environments.
For instance, a robot may reconfigure into a manipulator, a crawler, or a legged one. This sort of adaptability enables self-reconfigurable robots to accomplish tasks in unstructured environments; such as space exploration.
Lattice: Modules are arranged in a 2D or 3D pattern or virtual grid that can be used as a guide for modules to determine their positions and form the new shape.
Chain: Modules are connected together in a string or tree topology. The modules reconfigure by attaching and detaching to and from themselves.
Mobile: Modules detach from the main body and maneuver independently using the environment to link up at new locations in order to form new shapes.
A self-repair system must have two qualities: the ability to self-modify, and the availability of new parts or resources to fix broken ones. Therefore, modular self-repair robots usually consist of redundant modules. Self-repair consists of detecting the failure module, ejecting the deficient module and replacing it with an efficient extra module. Such robots are well suited for working in unknown and remote environments.
CEBOT was developed in 1990 as a distributed robotic system consisting of cells that could attach together to perform a function. These cells can automatically communicate, attach, and detach to perform a function, which allows the system to self-assemble and self-repair.
Self-assembly: CEBOT self-assembly method is designed for a small homogeneous local system that consists of around 10 units. Those units are connected in an arbitrary shape and one unit is chosen to be the origin of construction or the kernel. The kernel gathers adjacent units to compose a logical connection network according to the embedded plan. This network is the first stage. The units involved in the first stage network then gather some surrounding units and form the second stage network. Repeating this process increases the stages, and the network grows stage by stage, approaching the target configuration. The difficulty in construction is low due to using the layer, which acts as a kind of coordinate system to reduce the volume of search spaces .
Self-Repair: Self-repair can be performed by degeneration of the system to the previous stage.
PolyBot is the first modular robotic system to demonstrate self-reconfiguration by changing its geometry and locomotion mode depending on the terrain type; rolling type for flat terrain, earthworm type to avoid obstacles.
G2 added electromechanical latches under software control. G3 modules are smaller and lacks the DC motor. It has instead a DC pancake motor which is flat for better mounting options.
Programming the motion of n-modular systems with large numbers of modules can be difficult. So, reconfigurations can be preplanned off-line between every member of the set and stored in a table to simplify the process especially when a fixed number of configurations is sufficient.
QQ. What is the class of PolyBot? Chain + Lattice
Crystalline is composed of atoms.
Crystalline module motion is controlled by attaching one Atom to a neighboring Atom and actuating the expansion or compression mechanism.
An individual module cannot relocate without help. However, by contracting and expanding a group of modules in a coordinated way, Atoms can move relative to a structure through the volume of Crystal on a concave structure.
Self-Reconfiguration + Self-Repair
Telecubes consists of Cube shaped modules, each with 6 DOF.
When it comes to reconfiguration, it is assumed the initial and final configurations overlap by at least one meta-module.
The reconfiguration algorithm: 1. Select a module that can begin motion based on the minimum Manhattan distance through the structure from this module to a module in the final structure. 2. Plan a route for that module through the structure that consists of Move, Roll, and S-Roll commands using a technique similar to the PacMan algorithm. 3. Execute the preplanned motions.
However, this algorithm lacks local decision making, completeness of reconfiguration or parallel execution.
M-TRAN is a distributed self-reconfigurable system composed of homogeneous robotic modules. The system can change its configuration by changing each module’s position and connection.
However, changing the posture of one module is difficult in some cases, as it involves two modules in cooperation and this makes the problem more complicated. To cope with such difficulty of planning, two types of software have been developed. The first is a motion design interface, which helps a human programmer to design a reconfiguration sequence and motion generation through a powerful graphic interface. The second is a locomotion planner for an M-TRAN cluster, in which the above difficulties are relaxed by introducing some regularity into the structure.
Zykov et al. used evolving controllers for a real dynamical-legged robot in 2004. The nine-legged machine, demonstrated in Fig. 6, is composed of two Stewart platforms back to back. The author used force-actuators which exact extension can be set. The controller architecture for this machine was an open-loop pattern generator that determines when to open and close pneumatic valves. The on-off pattern was evolved and candidate controllers were evaluated by trying them out on a robot in a cage. Fitness was measured using a camera that tracks the red ball on the foot of one of the legs of the machine
3-D printing, are becoming increasingly accessible due to their ability of achieving complex geometries.
3D Printing allows fabrication of low cost, capable, agile, functional 3-D robots; such as Origami robots.
Those robots can fold themselves into functional 3-D machines employing origami-inspired techniques.
Former: Design Latter: Reproduction
Lipson et al. proposed an approach based on the use of only elementary building blocks and operators in design and fabrication process. Elementary building blocks were used to minimize inductive bias and maximize architectural flexibility. Also, they allow the fabrication process to be more systematic and versatile.
Nasa Datanauts Water Cooler Chat: Evolutionary Robots for Space Exploration
• The goal is to create systems:
• Low cost
• Modular robots are composed of various units or
• Each module involves actuators, sensors, computational,
and communicational capabilities.
• Modularity allows robots for self-assembly, self-
reconfiguration, and self-repair.
• Constructing complex multi-unit system using simple
• Perform tasks in remote environments.
• Allows robots of metamorphosis, which in turn makes
them capable of performing different sorts of kinematics.
• Allows a robot to replace damaged modules with
functional ones in order to continue with the task at hand.
• Allows robots to reproduce themselves from an infinite
supply of parts using simple rules.
• If the resulting system is an exact replica of the original,
the system is called a self-replicator.
• Evolutionary Robotics is a method for the automatic
creation of autonomous robots.
• Inspired by the Darwinian principle of selective
reproduction of the fittest captured by evolutionary
Zykov et al. 2004
• 3-D printing, are
• 3D Printing allows
fabrication of low cost,
functional 3-D robots;
such as Origami
robots. Onal et al., 2014
• Combines evolutionary
Lipson and Pollack., 2000
• In this presentation, we have presented a comprehensive
survey of modular robots that were created to meet three
main goals, versatility, robustness, and low cost.
HOW CAN WE USE THESE
ROBOTS FOR SPACE &