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LEGO SHRIMP Rover robot

Here is my attempt at a SHRIMP rover. This robot chassis adapts passively to the surface it is driving over. It can climb over many obstacles, including books, a pillow and even stairs! It is really an amazing piece of work, and is very simple to build.

Each wheel is driven by its own motor, so you will need six motors in total to build this chassis. The rear motor is fixed permanently to the chassis body, and the remaining five motors are on pivoting legs.

As you can see to the left, the motor is directly connected to the drive axle via a worm gear. The worm gear provides both torque and hold for the wheel. If the motor stops rotating, the wheel is locked in place. Thus the robot can hold itself in place on an oddly shaped obstacle.

The image to the right shows a side view of the leg. The key component is the gearbox which houses the worm gear and the drive axle. I experimented with a number of designs before hitting on the one shown below.

The image to the left shows the gearbox holding the worm gear and drive axle. The SHRIMP rover uses a modified version with shorter axles. The advantage to this design is its weight and strength.

Each side of the chassis has a pair of wheels mounted on legs. The legs are connected by two cross bars and pivot at two points. The crossbars are themselves connceted to the chassis at two points. Thus the leg pair can ride up and over an obstacle indepdently of the main chassis body.

The front wheel is connected to the body but can pivot at both the body connection and at the leg. The front wheel can ride up and over an obstacle while the body trails behind. It then pulls the chassis over the obstacle allowing the side wheels to drive. The rear wheel is permanently engaged and drives the chassis over an object.

The rover can lever itself over many obstacles. The picture to the left shows the wheels adapting to the tires placed below each leg.

The following four photos show how the rover can climb over an obstacle and adapt its body structure as it does so.