Robot kinematics uses geometry to describe how a robot’s connected parts move. It helps answer questions such as: Where will the tool end up if the joints move? Which joint motions are needed to reach a target? How do joint speeds relate to the tool’s speed?
A robot can be modeled as a kinematic chain: rigid links connected by joints. In the geometric model, links are treated as rigid bodies, while joints commonly allow either revolute motion (rotation) or prismatic motion (translation). Each independently adjustable joint parameter contributes to the robot’s degrees of freedom.
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What is robot kinematics?
Robot kinematics applies geometry to describe the configuration and motion of a robot’s links and end effector, without focusing on mass and inertia.
How do forward and inverse kinematics differ?
Forward kinematics computes the end-effector pose from given joint parameters. Inverse kinematics seeks joint parameters that achieve a specified end-effector pose.
What is an end-effector twist?
A twist is a six-component description of the end effector’s instantaneous linear and angular velocity.
What is a robot singularity?
A singular configuration is one where the Jacobian loses rank. Some end-effector motions may become unavailable, and nearby motion or force relationships can become poorly conditioned.
How does the Jacobian relate wrench and joint torque?
Under a common convention, virtual work gives τ=JTW, where W is the end-effector force-and-torque wrench and τ is the joint-torque vector.
Quiz questions
In a geometric model of robot kinematics, how are links and joints commonly represented?Answer: Rigid links are connected by joints that commonly rotate or translate.
What does forward kinematics compute from specified joint parameters?Answer: The resulting end-effector pose.
What is a robot’s workspace?Answer: The set of positions reachable under its dimensions and kinematic constraints.
In velocity kinematics, what does the Jacobian relate?Answer: Joint rates to the end effector’s linear and angular velocity.
What mathematical condition defines a singular robot configuration?Answer: The Jacobian loses rank at that pose.
Based on the Wikipedia article Robot kinematics, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.