Introduction to Manipulation

Now that we’ve covered different ways of controlling your robot’s movement, let’s cover how we can control the robot’s arm to manipulate our environment.

The XRP Arm

Every robot needs to be able to interact with it’s environment.

Your XRP does this with a simple 1 DOF arm.

In this case, “DOF” stands for “Degree of Freedom” and refers to the number of ways the arm can move.

Accurate Control of the XRP arm

To move your XRP’s arm, use this function:

servo.set_angle(angle)

In this case, the function takes in a single argument, which is the angle in degrees that you want the arm to move to. The angle has a range of [0, 135] degrees.

Try it out

Try writing code that moves the arm to an angle of 90 degrees, sleeps for 1 second, and then moves the arm back to an angle of 0 degrees.

Other Robotics Manipulators

There are many types of robotic manipulation. Here is a very complicated example, where Boston Dynamics’ Spot robot opens a door and lets itself in.

The XRP arm is a very simple manipulator.

Most robots have more complex manipulators, with more degrees of freedom.

For example, Boston Dynamic’s Spot robot has a 5 DOF arm that can be used to open doors, turn valves, and even pick up objects.

For more complicated manipulators like the one that Spot has, roboticists often have to create control laws specific to those manipulators.

In the case of Spot, the arm is equipped with a camera that help Spot better understand it’s environment and avoid obstacles while trying to use it’s arm.