Blender Advanced: Forward Kinematics (FK) and Inverse Kinematics (IK)

Name: Blender Advanced: Forward Kinematics (FK) and Inverse Kinematics (IK)
Author: Jay Grewall

Learn how to create real-world mechanical motion using Forward Kinematics and Inverse Kinematics in Blender

Preview the first lesson free — get full access to all 7 lessons.

Course: On-Demand

Hello, and welcome to Knowledge City's course on Advanced Blender 3D. My name is Jay, and today we'll be learning about Forward Kinematics, or FK for short. FK is an animation technique in which a series of objects is connected at their respective ends to form an articulating chain of motion. FK uses parent-child relationships to define the behavior of the series, where the parent directly influences the child. I have here four parts which will be used to rig an articulating robot arm using a ball and socket mechanism, and you can see the sockets I have created right here. This lesson isn't so much about modeling or texturing, as you can see, but rather about rigging an FK series of objects to be animated based upon its parent object. I've applied these wacky colors to the object, so it'll be easier for us to see the modification take place. I've given each object an identifiable name here in our scene collection, and removed the lights and camera, and I've set up my 3D viewport to display the name of each object. This can be done simply by selecting on the Object Properties tab at the right, going down to Viewport Settings, and clicking on Name. For this rig, arm 1 will be the child of the base, and the socket will rotate around the ball of the base. Arm 2 will be the child of arm 1, and the socket will rotate around the ball of arm 1. And the hand will be the child of arm 2, and the socket of the hand will rotate around the ball of arm 2. So let's start rigging this robot arm by placing each object in its place. The most important thing to keep in mind when rigging is that each object needs to be in its exact position, size, and rotation before we do anything. This includes the pivot point. At the moment, the pivot point of each object is not in its correct place. When we rotate an object, this is what happens. So we need to adjust the pivot point of each object so it rotates around its respective parent part, and we're going to do this by entering Edit Mode. Another use for activating the name of each object is that its name is at the exact coordinates of 0, 0, 0 on our XYZ plane. And this is where I want the pivot point to be. And to be extra sure of where I am moving my object, I'm going to be using the Transform tool, which gives us this gizmo, allowing us to restrict the motion in one particular axis. When I exit Edit Mode, you'll see all my objects have changed. This is because the pivot point of each object has changed. Now all I need to do is place them in their correct positions. Now each object is rotating around its correct pivot point. Now that we've arranged the parts, we need to set up the parent-child relationships between each one. I'm going to choose the child first and then its parent. On my keyboard, I'm going to press Ctrl P and go to Object. A quicker way to do this is by heading over to the Scene Collection panel, choosing the child, and clicking and dragging it directly on top of its parent while holding down the Shift key. Now we can see the hierarchy, but there's a problem. We see that the socket of a ARM 1 goes through the base when we rotate it. A real robot ARM would not do this. Technically, we could just limit the rotation when we animate the rig, but this wouldn't be too efficient. So we're going to tell Blender where the rotation needs to stop. To do this, we're going to click on the Object Constraints tab at the right, click on the drop-down menu called Add Object Constraint, and select Limit Rotation. We know that we want the rotation to take place on the X and Y coordinates, but how much? Underneath our Limit Rotation, we have the ability to apply a limit to the X, Y, and Z coordinates. I'm going to activate the X rotation, and we now need to determine how much it can rotate. I'm going to rotate it to about this angle, which looks to be about 70 degrees, so we know this rotation needs to be limited to 70 degrees. I'm going to activate my Limit X rotation and type in negative 70 for the minimum and positive 70 for the maximum. Now I cannot rotate no matter how far I try. We need to apply the same limitation to the Y-axis, so I'm going to press on the icon associated with Y and input the same values, and being that we want it to rotate around our Z-axis, we do not need to apply any constraints. So I'm going to leave the Z-rotation constraint alone. I'm going to apply the same constraint to the rest of the objects. Now we're ready to animate the robot arm, and we're going to animate the rotation of each object in increments of 20 seconds. I'm going to activate my Auto King, select all the objects, press I on my keyboard to insert a keyframe, and select the rotation. I can also offset the keyframes so that they don't all happen at the same time. And this is how we animate a robot arm using Forward Kinematics in Blender. Thank you very much for watching.

Advanced Provider : Jay Grewall 7 Lessons · 42m in English

Course Description

Knowing how to unleash the creative potential of rigging and animation in Blender is important, as it allows you to elevate your designs to new heights with captivating realism and dynamic motion. By exploring Forward Kinematic and Inverse Kinematic techniques, you will gain the ability to give your creations and projects more accurate and lifelike mechanical movement. Understanding the versatility of armature bones empowers you to animate modular patio furniture and other objects, adding a touch of fluidity and authenticity to your designs. No matter the project, Blender provides you with the tools to unleash your creativity and transform your designs into captivating visuals that leave a lasting impression.

In this course, you will learn the difference between Forward Kinematics (FK) and Inverse Kinematics (IK) in Blender. You will learn how to use the Graph Editor to create dynamic animation, and how an Empty 3D object can affect other objects in your scene. By the end of this course, you will be able to rig and animate the mechanical motion of 3D objects.

What You'll Learn

Distinguish Forward Kinematics (FK) from Inverse Kinematics (IK) in Blender
Explore the two different methods of Inverse Kinematics
Use the Graph Editor and Graph Modifiers to create dynamic animation
Apply armature bones to rig and animate mechanical motion of 3D objects
Build practical projects such as modular patio furniture and an IK-driven piston
Use an Empty 3D object to affect other objects in your scene

Key Takeaways

Forward Kinematics and Inverse Kinematics are distinct techniques for producing accurate, lifelike mechanical movement in Blender.
Inverse Kinematics can be implemented through two different methods covered in the course.
The Graph Editor and Graph Modifiers are used to create dynamic animation.
Armature bones let you animate objects such as modular patio furniture with fluid, authentic motion.
An Empty 3D object can be used to affect and drive the motion of other objects in a scene.

Frequently Asked Questions

What will I be able to do after completing this course?

By the end of the course you will be able to rig and animate the mechanical motion of 3D objects in Blender.

What topics does this course cover?

It covers the difference between Forward Kinematics (FK) and Inverse Kinematics (IK), the two methods of Inverse Kinematics, using the Graph Editor and Graph Modifiers for dynamic animation, armature bones, Empty objects, and projects like creating modular patio furniture and an IK-driven piston.

What skills will I gain from this course?

You will gain skills in Forward Kinematics, Inverse Kinematics, Kinematics, and Object Animation, with exposure to tools including Autodesk Animator and Autodesk MotionBuilder.

What lessons are included in this course?

The lessons are Forward Kinematics, Inverse Kinematics (Part 1), Inverse Kinematics (Part 2), Creating Modular Patio Furniture, Creating an IK-Driven Piston, Graph Modifiers, and Empty Objects.