Adaptive variable impedance control

Hi, how can I use the blocks of simulink to build the formula of variable impedance law, thank you

Answer 1

[Sam Chak]

Hi @Edgar Yang

I'm unfamiliar with your control thing because I cannot find where the adaptive law of variable impedance is.

Nevertheless, if the law is static (e.g., PID control), then you can use MATLAB Function block. And if the law is dynamic (e.g., super-twisting sliding mode control), then the S-function block is preferable.

[Edgar Yang]

Thank you for your reply, I want to use a block diagram to build a system with this architecture

[Sam Chak]

Hi @Edgar Yang

You can create the Robot system in this proposed Simulink setup as shown. The Subsystem block is where you should build around red dotted lines, and it consists of multiple blocks.

https://www.mathworks.com/help/simulink/ug/systeml-mask.html

[Edgar Yang]

Thank you for your reply. Since I just started using matlab recently, there are many things I don’t understand. I would like to ask you how to design the subsystem adaptive controller and s-function robot dynamics in the above picture. At present, I am directly building according to the equation Model

[Sam Chak]

Hi @Edgar Yang

The image in my comment was simply an overview of what I believe an organized Simulink model of a nonlinear coupled multi-input, multi-output system (such as many robotic systems) should look like. In fact, I didn't write any code for the Robot Dynamics (in the S-function block) or the Robot Kinematics (in MATLAB Function blocks). Moreover, inside the Subsystem block mask, they are merely connectors between the input ports and the output port.

Nevertheless, for a beginner, it is perfectly acceptable to build the system using fundamental blocks as you did above, although it can be tedious and challenging to visually interpret the signal flow for multiple inputs and outputs. There is a saying, "Learn to walk before you run." By mastering the fundamentals, you will eventually grasp the concept of mathematically interpreting how signals flow between the output ports of one block and the input ports of another block in Simulink.

Tips: 💡

I suggest that you start by building a single-link robot at the beginning because the kinematics and dynamics are super simple to interpret mathematically. In theory, the adaptive law should be applicable to a single link or an n-link robotic arm. If there are errors in the simulation of the single-link robot, it will be easy for you to troubleshoot and fix the problem. Once the simulation is successful, you can add a second link and update the Simulink model accordingly, either by modifying some blocks or adding a group of blocks with the same configuration as the single-link robot.