Conceptualization of the Gripper

This section outlines the proposed gripper concepts, discussing their advantages and disadvantages, and explains the rationale behind the final design choice. Four concepts were made for the gripper based on research.

Concept 1

Concept 1 aims to combine simplicity with dexterity. A review of both Mars rovers and competitor designs reveals that the gripper is typically a simple element. The reason behind this fundamental design is to minimize failure points while dealing with extreme environmental conditions and unpredictable terrains. For real Mars missions, it is even more crucial to design a durable gripper because human intervention for repairs and maintenance is not possible during deployment. The gripper must perform reliably over extended periods without direct support.

This design presents two-part jaws, simultaneously actuated by a drive system of three gears and a motor. A second motor is used with another set of gears to rotate the gripper around the x-axis. The shape of the jaws is made such that when the jaws are released, the gripper closes in a pointy shape to allow precise manipulation of buttons and switches.

Concept 2 Concept 2, the finger gripper, proposes an end-effector that prioritizes dexterity over simplicity. Many available research papers present finger grippers and various mechanisms to build them. The complexity of this type of mechanism creates a certain challenge for the control subteam. Additionally, the high number of small parts required in the assembly increases the risks of mechanical failure in the conditions that the robot is expected to face.

This end-effector is composed of four fingers made of four phalanges each. The fingers are placed in parallel. Actuation is achieved through a filament connection that passes over several pulleys placed inside the phalanges. The fingers are actuated by a drive system that combines the pulleys, a gearbox, and motors. The rotation around the x-axis is enabled by a set of bevel gears combined with a motor.

Concept 3 Concept 3 is based on industrial grippers, focusing on simplicity and durability over dexterity. Their simple design works well for standard shapes as the grippers have a fixed shape. The jaws are shaped so that when the gripper is closed, the end-effector forms a point, allowing for precise manipulation of buttons and switches. This gripper is not usually applied to Mars rovers.

Concept 3 actuates the two fixed jaws with two rack and pinion systems connected to a motor each. While the fixed jaw shape limits adaptability to irregular objects, the straightforward design offers high reliability, ease of control, and reduced risk of mechanical failure during long-duration missions. Additionally, the 1-DOF rotation is ensured by a pneumatic rack and pinion actuation, driving a gear system connected to the rest of the gripper.

Concept 4 Concept 4 is inspired by competitors' robotic arm grippers. The simplicity of this mechanism is inspired by real Mars rovers. This end-effector design provides a reliable and rigid system. The lack of dexterity is compensated for by an additional system using a rack and pinion system. A key advantage of this concept is its low part count, which reduces the risk of mechanical failure and enhances overall durability.

The presented concept is composed of two jaws. The smallest jaw can be actuated while the large jaw is fixed. The rack and pinion system is placed underneath the fixed jaw and actuates a plastic rod that can be used to operate switches and buttons. This system was combined with a belt, pulley, and gear system to add the 1-DOF to the gripper.