One-DOF six-bar space gripper with multiple operation modes and force adaptability

For complex space tasks, the gripper is expected to adapt to items of different shapes and sizes; it has the advantages of simple control and acceptable force adaptability. Therefore, a one degree of freedom (DOF) six-bar space gripper with good task adaptability is developed. Design constraints are analyzed on the basis of typical grasping task analysis. A design method based on proportional coefficients is proposed, considering that the constraints are complex and the six-bar mechanism has many design parameters. The design efficiency can be improved by reducing the target trajectory according to proportional coefficients. The one-DOF six-bar mechanism that satisfies the final constraints has multiple operation modes with only one drive. On this basis, the elastic element is added as part of the mechanism rather than outside the mechanism, and a rigid-flexible coupling mechanical model is established to further analyze the effect of elastic element on the force adaptability. Experiments show that the designed one-DOF gripper can grasp cylinders with different diameters and grasp and move items of different sizes with fingertips under different space constraints; it also has good force adaptability. This finding provides a reference for reducing the complexity of gripper and improving the diversity of grasping task.