Knot tying device and method

A knot tying device, comprising:

• a support with a gripper element, wherein one end of the gripper element is rotatably connected to the support, and the other end is capable of being pressed on and released from the support;
• a gripper mechanism to grip a free end of a strand or bundle of material and carry the strand or bundle of material to wrap around the support, wherein the support is capable of rising and falling;
• after the gripper mechanism carries the strand or bundle of material to wrap around the support at a position below the gripper element by at least half of a circle, the support falls;
• the gripper mechanism continues to carry the strand or bundle of material to wrap around the support so as to carry the strand or bundle of material to pass through a space between the support and the gripper element;
• and then the gripper element is pressed on the support so as to make the free end of the strand or bundle of material fixedly gripped between the gripper element and the support;
• and
• a stripping mechanism to separate the strand or bundle of material wrapped around the support from the support to form a knot.