Background: The designs of already-existing quadruped robots are all quite similar, either similar to Boston Dynamics' Spot, MIT's Cheetah, Unitree Robotics' Laikago or Go1, or to the ANYbotics' ANYmal. The first group share a crucial aspect of the leg design: all leg motors are located in the shoulder joint, reducing the force that would be otherwise required if motors were located one in the shoulder and one in the elbow joint. In this design, the elbow is controlled using an extension linkage. ANYmal (and other similar designs), however, have one motor in the shoulder and one in the elbow, clearly visible due to a bulky round box on each leg of the robot. The only quadruped robot I could find that does not conform to these two design types is ETH's SpaceBok. Additionally, this is the only quadruped robot specifically designed for space exploration. Its leg design is fascinating since it is based on four parallel linkages controlled by two motors located on the shoulder joint. It strongly relies on energy conservation to jump using the back drive of brushless motors, simulating a spring.
Comment: By observing all of these designs, it is clear they cannot be considered "rovers": the majority of the robot body is occupied by the motors and the battery, and there's very little space available for cargo. Indeed, they can carry much weight, but it has to be stored on top of the robot, increasing the overall height of the centre of mass. Cameras are either located in front of the robot or on each side of its body, making them not ideal for observing the surroundings: they are suitable for finding obstacles but utterly useless for collecting imaging data of the surroundings. Expensive and custom motors are used to control the legs; brushless motors are usually relatively weak and require using a gearbox. This means increasing the overall robot weight and space occupied by the actuators inside the robot body.
I proposed a completely different approach that merges the valid aspects of existing designs with the peculiar characteristics of NASA/JPL's Mars Rovers. A mast tower is located on the top-front part of the body, raising the primary camera at a higher point, allowing it to rotate on the vertical axis (azimuth) and pitch rotation (elevation). Apart from other technical design choices discussed in the spacecraft section of this blog, it is visible that much space is available on the rover body: cargo is an essential part of Continuity and can be stored on the robot's upper deck or the side module located on the side of the mast tower. I decided to use high-torque full-metal servo motors instead of brushless motors because they guarantee an extremely high torque (about 25 Kg on the 1st cm of radius from the shaft) relative to their small scale and have incredibly high precision. Interestingly, Martin Marietta walking rover was designed with some of these elements, too: the mast tower and an upper deck are also present in that design!