Six degrees of freedom refers to the freedom of movement of a rigid body in three-dimensional
space.
Specifically, the body is free to move forward/backward, up/down, left/right combined with rotation
about three perpendicular axes, often termed pitch, yaw, and roll.
Robotics Serial and parallel manipulator systems are
generally designed to position an end-effector with six degrees of freedom, consisting of
three in translation and three in orientation.
This provides a direct relationship between actuator positions and the configuration of
the manipulator defined by its forward and inverse kinematics.
Robot arms are described by their degrees of freedom.
This number typically refers to the number of single-axis rotational joints in the arm,
where higher number indicates an increased flexibility in positioning a tool.
This is a practical metric, in contrast to the abstract definition of degrees of freedom
which measures the aggregate positioning capability of a system.
In 2007, Dean Kamen, inventor of the Segway, unveiled a prototype robotic arm with 14 degrees
of freedom for DARPA.
Humanoid robots typically have 30 or more degrees of freedom, with six degrees of freedom
per arm, five or six in each leg, and several more in torso and neck.
Engineering The term is important in mechanical systems,
especially biomechanical systems for analyzing and measuring properties of these types of
systems that need to account for all six degrees of freedom.
Measurement of the six degrees of freedom is accomplished today through both AC and
DC magnetic or electromagnetic fields in sensors that transmit positional and angular data
to a processing unit.
The data are made relevant through software that integrate the data based on the needs
and programming of the users.
Ascension Technology Corporation has recently created a 6DoF device small enough to fit
in a biopsy needle, allowing physicians to better research at minute levels.
The new sensor passively senses pulsed DC magnetic fields generated by either a cubic
transmitter or a flat transmitter and is available for integration and manufacturability by medical
OEMs.
An example of six degree of freedom movement is the motion of a ship at sea.
It is described as: Translation:
Moving up and down; Moving left and right;
Moving forward and backward; Rotation
Tilting forward and backward; Turning left and right;
Tilting side to side.
Game controllers Six degrees of freedom also refers to movement
in video game-play.
First-person shooter games generally provide five degrees of freedom: forwards/backwards,
slide left/right, up/down, yaw, and pitch.
If the game allows leaning control, then some consider it a sixth DoF; however, this may
not be completely accurate, as a lean is a limited partial rotation.
The term 6DoF has sometimes been used to describe games which allow freedom of movement, but
do not necessarily meet the full 6DoF criteria.
For example, Dead Space 2, and to a lesser extent, Homeworld and Zone Of The Enders allow
freedom of movement.
Some examples of true 6DoF games, which allow independent control of all three movement
axes and all three rotational axes, include Shattered Horizon, the Descent franchise,
Retrovirus, Miner Wars, Space Engineers and Forsaken.
The space MMO Vendetta Online also features 6 degrees of freedom.
The acronym 3DoF, meaning movement in the three dimensions but not rotation, is sometimes
encountered.
The Razer Hydra, a motion controller for PC, tracks position and rotation of two wired
nunchucks, providing six degrees of freedom on each hand.
The SpaceOrb 360 is a 6DOF computer input device released in 1996 originally manufactured
and sold by the SpaceTec IMC company.
See also Degrees of freedom
Ship motions, an example in a vehicle.
References