Six degrees of freedom

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

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