Snapbot is the latest robot developed by Disney research team. With a body and six detachable legs, the spider like form is modular and can reconfigure different types of movements in many different ways.

What makes snapbot different

Snapbot development focused on its reconfigurable capabilities while still maintaining mobility. Whether only one leg is connected or a complete six legs are connected, the robot can still walk.

Although there have been many researches on the variable structure of legged robots (one foot, two feet, four feet, six feet, etc.), most of these robots have model-based settings. So, you can set the robot into a three legged scheme, install three legs, and then watch the robot go.

Through snapbot, the embedded algorithm “reads” the configuration of the robot and adjusts its motion mode accordingly. This means that after an “injury”, such as the loss of a leg, it can adapt to its own behavior.

Snapbot components

The hardware of the snapbot consists of a 3D printer body and six legs.

The main body is the central hub of the robot. Its shape is like a hexagon. The six sides provide interfaces for six legs. There are six triangular supports at the bottom, which can reduce the friction between the robot and the ground.

It is equipped with a 7.2-volt lithium-ion battery to provide a plug-free power supply for the machine. It also has an opencm9.04 microcontroller, which provides processing power for the machine. The microcontroller is connected to the body frame with four rivets. The data from the microcontroller is directed to two hubs, and each hub transmits the data to the three nearest fulcrums.

The total width of the body is close to 3 inches, and the weight, including batteries and electronic devices, is about 0.4 pounds.

Then, each module leg is attached to the main body in a radial form, which is different from the anthrobot, which has 6 legs, and each leg has 3 legs on both sides of the main body.

Snapbot can connect up to six legs, but three legs provide three different ways to move. The three leg types are roll, sway and sway. Each leg is 3D printed and cannot be disassembled as a single joint part. Each leg uses the dynamixelxl-320 position control servo. There is a rubber head on the foot, which can help the leg withstand the pressure and impact brought by movement.

The design focus of this leg is to maintain the light weight of the part while still allowing a certain degree of structural integrity. Each leg weighs between 0.19 and 0.026 pounds, depending on the type of leg.

So what inspired snapbot

Like other robots inspired by nature, snapbot is also inspired by animals. They pay special attention to those who have the ability to change the configuration according to the environment. Animals like starfish can not only change from a sitting position to a standing position like humans, but also take the initiative to separate from one limb to avoid predators, and then grow limbs again.

The report also cites the ability of insects to walk after losing one or more of their six legs. It also cites the metamorphosis experienced by frogs – the growth of two pairs of legs and the loss of a tail.

In the process of designing the robot, researchers also studied other modular robot systems, which have smaller modular components and unified couplings. In addition, the researchers also studied how machine learning technology was used to create robots that could adapt to environmental changes or configuration changes.

How it works – joinery

The legs of the robot are separated and reconnected by magnetic force. Each leg of the robot consists of four magnets, which can easily pull down the legs or put the hind legs on the body. The magnet is also arranged to be connected to the correct part direction using polarity restriction.

But these are not simple magnet joints. At the center of each coupling is an 8-pin spring-loaded electrical connector. This connector transmits power to the leg, and data tells the leg what to do.

How it works — kinetic mechanics

In snapbot, the microcontroller placed in the center of the robot is the origin of the mobile algorithm. The microcontroller works in real time to determine the configuration of the robot’s legs; It then determines its motion path based on the number of attached legs.

For this iteration, the movement of the snapbot is limited to a straight line, but the processor still has many variables to calculate. There are only one type of leg with 14 different leg configurations, but there are three types of legs with 700 possible leg configurations.

To evaluate the current configuration of the legs, the controller pings the server on each leg to determine the type of additional legs. It determines the position of each type of leg by connecting the server data cable to the connector pin of the controller. This configuration scans every 100 milliseconds.

The processor then calculates the forward kinematics based on the configuration. The three types of leg movements are rowing, crawling and walking. When there is only one leg, the robot will use the action of rowing to drag the body. In any two leg configuration change, the robot uses a crawling motion to maximize rolling joint motion to create better ground contact with the feet and drag the body. Among the leg combinations that are possible to walk, snapbot can lift his body from the ground and walk forward with two diagonal legs.

Future development of snapbot

Snapbot demonstrated the variable configuration model using modular legs and the adaptability using real-time machine learning, and this robot is a stepping stone in the company’s discovery process.

It “will be used for further leg movement research,” Disney research said. In particular, the research team plans to explore how snapbot can benefit from the growth of evolutionary algorithms and sensors such as cameras.

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