10.8.1. Advantages of Redundancy

• Greater flexibility.

Kinematic redundancy allows a robotic manipulator to have more degrees of freedom (DOFs) than what is strictly necessary to accomplish a given task. This means that there are multiple ways for the robot to complete the same task, allowing it to adjust its configuration based on external conditions or constraints. For example, if an obstacle blocks the direct path of the end-effector, the redundant DOFs enable the robot to reposition its joints to create an alternative path to reach the target without needing to retract or stop.

Think of a traffic intersection: multiple routes can lead to the same destination. If one road is blocked, a driver can take another route, ensuring they still reach their destination efficiently. Similarly, a redundant robot can take a different 'route' to position its end-effector.

• Collision avoidance.

With more DOFs available, redundantly configured robots can maneuver themselves in a way that avoids collisions with obstacles in their environment. This is particularly important in complex workplaces, such as construction sites, where many obstacles may exist and where the robot needs to safely navigate without interrupting its task or damaging itself or its surroundings.

Imagine playing a game of dodgeball. If you are agile and have many ways to move, you can quickly change direction to avoid being hit. Similarly, a robotic manipulator with redundancy can adjust its positions and angles to avoid colliding with obstacles, ensuring effective operation.

• Joint limit avoidance.

Redundant robots can manage their joint limits more effectively. Each joint in a robotic arm has a range of motion that it cannot exceed. With redundancy, the robot can choose joint configurations that keep all joints within their respective limits while still executing the desired tasks. This capability extends the operational life of the robot by minimizing wear and potential damage from exceeding joint limits.

Consider a human dancer performing a routine. If the dancer knows their limits (like the maximum height their leg can reach without injury), they can adapt their movements while still delivering an impressive performance. Likewise, a redundant robot avoids strain on its joints while achieving its tasks.

• Singular configuration avoidance.

Robotic manipulators may encounter singular configurations where they lose the ability to move in certain directions, which can limit functionality and control. A kinematically redundant robot has the ability to maneuver around these singularities by utilizing its additional DOFs to maintain a more stable and functional configuration that allows for continued motion and control even in challenging orientations.

Think of sailing a boat. If the wind changes direction sharply, the boat could struggle to move forward, effectively becoming 'stuck.' However, if the sailor has multiple sails and techniques to adjust, they can change their course to keep sailing smoothly. In robotics, redundancy provides the flexibility to avoid getting 'stuck' in configurations that limit movement.

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