Software Control system

Introduction THE mantis forelimb shares its basic

structure with that of other insects, which

typically utilise them exclusively as the

front pair of legs. However, the mantis

forelimb has evolved with a different

primary purpose while retaining its leg-like

functionality. The main use of the mantis

forelimb is to catch and hold prey, which is

often of a similar size to the mantis itself.

Behavior Analysis The movements of mantis arm can be

separated in two parts.

1. Normal Movements

2. Hunting motions

During normal movements, mantis use

its arm as two extra foot, which

increase its stability and flexibility.

When the mantis found its prey, the

mantis will reach its whole body as

close as possible to its object. Then

reach out its arm at a sudden, once

the hook over the prey, it will close its

hook immediately.

The arm will hold the prey tidily and

send it to its mouth part.

Kinematics 1. Calculate the range of the arm

2. The rotations of servo motor

The first step will give a result of the range of

the robotic arm. All points shows in the figure

above represents a position and the

corresponding rotation for servo motors.

The second step is to figure out the rotation for

the motor in point C in the figure above. The

idea is to find all possible combinations for

points in circle B and circle C that have a

distance equal to the length of L.

Hardware design Our arm uses Arduino as the centre controller

and combine it with a motor driver board,

using I2C communication.

The power is supplied by a 6v 5packs battery.

Two distance sensor for detecting the distance

and a force sensor to detect whether the arm

have gripped the object.

The arm is driven by 5 servo motors, they been

placed at the joints of the arm, they can

provide a reasonable torque and speed.

The main body of the arm is combined with

Acrylic board, which been processed with

laser cut. This material can ensure the strength

of whole structure.

The control flow starts

from initialization of the

robot, then waits to be

triggered. The arm moves

to the position to required

to try to grip the object. If

the sensor detects a force

in the gripper, it will pick

up the object and pull it

back, otherwise, it will

repeat the motions again.

Mantis Arm Group:

Elliot Skinner, Lei Zhang, Qiming Wang,

Huangxin Que & Yichao Pan