Designing a controller that balances two links adds an extra challenge when compared to the single inverted pendulum system. The additional challenge of a second pendulum can be used to demonstrate advanced controls concepts, or as a basis for research.
Linear Double Inverted Pendulum
The double inverted pendulum represents a complex challenge with real-world applications that include stabilizing the takeoff of a multi-stage rocket and modeling the human posture system.
The 2 DOF Inverted Pendulum module consists of an instrumented 2 DOF joint to which a 12-inch rod is mounted. The rod is free to swing about two orthogonal axes. The module is attached to two Rotary Servo Base Units. Their servomotors’ output shafts are coupled through a four-bar linkage, i.e., 2 DOF Robot module, resulting in a planar manipulator robot. The 2 DOF Joint is attached to the end effector of the robot arms. The goal of the 2 DOF Inverted Pendulum experiment is to command the position of the 2 DOF Robot end effector to balance the pendulum. By measuring the deviations of the vertical pendulum, a controller can be used to rotate the servos, so that the position of the end effector balances the pendulum.
The 2 DOF Robot module is connected to two Rotary Servo Base Units, which are mounted at a fixed distance. Two servomotors on the Rotary Servo Base Units are mounted at a fixed distance and control a 4-bar linkage system: two powered arms coupled through two non-powered arms. The system is planar and has two actuated and three unactuated revolute joints. The goal of the 2 DOF Robot experiment is to manipulate the X-Y position of a four-bar linkage end effector. Such a system is similar to the kinematic problems encountered in the control of other parallel mechanisms that have singularities.
The Linear Motion Control Lab is one of the most popular, flexible and modular solutions for teaching controls. Based on the world’s leading turn-key platform for controls education, it is designed to help engineering educators reach a new level of efficiency and effectiveness in teaching controls.
The Active Suspension consists of three masses that along stainless steel shafts using linear bearings and is supported by a set of springs. The upper mass (blue) represents the vehicle body supported above the suspension, the middle mass (red) corresponds to one of the vehicle’s tires, and the bottom (silver) mass simulates the road. The upper mass is connected to a high-quality DC motor through a capstan to emulate an active suspension system that can dynamically compensate for the motions introduced by the road. The lower plate is driven by a powerful DC motor connected to a lead screw and cable transmission system.
The experiment is reconfigurable for various aerospace systems, from 1 DOF and 2 DOF helicopter to half-quadrotor. Integrating Quanser-developed QFLEX 2 computing interface technology, the Quanser AERO also offers flexibility in lab configurations, using a PC, or microcontrollers, such as NI myRIO, Arduino and Raspberry Pi. With the comprehensive course materials included, you can build a state-of-the-art teaching lab for your mechatronics or control courses, engage students in various design and capstone projects, and validate your research concepts on a high-quality, robust, and precise platform.
Same as the physical Quanser AERO, the virtual system is a dual-rotor helicopter model that can be reconfigured for 1 DOF attitude, 2 DOF helicopter, or half-quadrotor experiments. Rotary encoders measure the angular position of the propeller DC motors, the speed of the motors is measured through a software-based tachometer.