4.7 KiB
Stewart Platforms
- Introduction
- Simulink Project (link)
- Stewart Platform Architecture Definition (link)
- Simscape Model of the Stewart Platform (link)
- Kinematic Analysis (link)
- Identification of the Stewart Dynamics (link)
- Control
- Cubic Configuration (link)
- Bibliography (link)
Introduction ignore
The goal of this project is to provide a Matlab/Simscape Toolbox to study Stewart platforms. The project is divided into several section listed below. The git repository of the project is accessible here.
Simulink Project (link)
The project is managed with a Simulink Project. Such project is briefly presented here.
Stewart Platform Architecture Definition (link)
The way the Stewart Platform is defined is explained here.
All the geometrical parameters are defined including:
- Definition of the location of the frames
- Location/orientation of the limbs
- Size/inertia of the platforms and the limbs
Other parameters are also defined such as:
- Stiffness and damping of the struts
- Rest position of the Stewart platform
Simscape Model of the Stewart Platform (link)
Kinematic Analysis (link)
From the defined geometry of the Stewart platform, we can perform static analysis such as:
- Jacobian Analysis that links the velocity of each limb to the velocity of the mobile platform
- Static Forces Analysis that links the forces applied by each limb to the resulting force/torque applied to the mobile platform
From the strut stiffness, we can also perform a Stiffness Analysis that consists of determining the Stiffness matrix and Compliance matrix of the Stewart platform from the geometry.
All these analysis are described here.
Identification of the Stewart Dynamics (link)
The Dynamics of the Stewart platform can be identified using the Simscape model.
It is possible to:
- Determine the dynamics from the actuators to the various sensors included in the Stewart platform
- Extract State Space models for further analysis / control synthesis
- Extract the Resonant Frequencies, Modal Damping, and associated Mode Shapes
The code that is used for identification is explained here.
Control
The use of active control for Stewart platforms is a wide subject. Many aspect can be studied.
The sensors used is of primary important. We can have:
- Sensors located in each strut: relative motion, force sensor, inertial sensor
- Sensors measuring the relative motion between the fixed base and the mobile platform
- Inertial sensors located on the mobile platform
The control objective can also vary:
- Reference Tracking
- Active Damping
- Vibration Isolation
The Control for Stewart platforms is here studied in the following files:
-
Active Damping (link). The use of different sensors are compared for active damping:
- Inertial Sensor in each strut or fixed to the mobile platform
- Force Sensor in each strut
- Relative Motion Sensor in each strut
- Motion Control (link). Different control architectures (centralized and decentralized) are compared for the position control of the Stewart platform.
- Vibration Isolation (link)