This project includes utilities that can assist the development of a robot's kinematic model.
This toolkit is currently capable of performing the multiple functions. The feature set in this toolkit will continue to expand with time. Current features include:
- Forward & Differential Kinematics expression compilation
- Visual robot rendering
- Kinematic chain support
Future features include:
- Inverse dynamics expression compilation
- Robot dynamics simulation
- Kinematic tree support
- Unit tests
Given a robot specification using Denavit-Hartenberg parameters, a robot's joint positions can be mathematically related to the pose of the robot's end effector. This toolkit exposes the Denavit-Hartenberg parameter technique using Transforms:
Transform(θ, d, a, α, joint_type)
θ : Angle about previous z, from old x to new x
d : Offset along previous z to the common normal
a : Length of the common normal
Assuming a revolute joint, this is the radius about previous z
α : Angle about common normal, from old z axis to new z axis
Joint Types:
Static : No actuated joint, transform is static
Prismatic : The transform 'd' parameter is set in accordance to the joint's value
Revolute : The transform 'θ' patameter is set in accordance to the joint's value
Note that the right hand rule for specifying axis orientation is always used.
A robotic manipulator is specified by creating a list of transforms, thus creating a kinematic chain. See example.cpp for a sample of how to create a robot manipulator. See example_out.cpp to view the output of the compilation executed in the example program.
This toolkit provides support for realizing a robot's forward kinematics and differential kinematics.
In tests on my machine, the compiled forward kinematics calculations execute 359.3x faster than forward kinematics applied by sequentially multiplying frame transforms for a simple 3-link RRR manipulator. This test was executed by running 100k forwards kinematics requests using both methods. The compiled method calculated all 100k requests in 0.06806 seconds, whereas the frame transform approach calculated all requests in 24.4526 seconds.
A simple renderer is used to show a visual representation of the kinematic chain. This is intended to assist in specifying the transforms that compose the robot geometry.
This shows a sample rendering of a robot with 6 revolute joints, each joint rotating at constant velocity in the same direction.
Symbolic C++ is copied directly into this repository. I have not modified nor contributed to the library, therefore all credit for Symbolic C++ goes to its developers. Symbolic C++ is used to symbolically compute the differential and forward kinematics prior to compilation.
SDL 2.0 is required to render the arm model visually.