Rotary Flexible Joint
This laboratory experiment is suitable for modeling the dynamic behavior of large robot arms with flexible joints. The following questions, among others, arise during the controller design for this system: How fast can the arm be brought into the target position? Is overshooting allowed (precision)? Are there acceleration limits that must not be exceeded? Does the mass of the object to be transported vary?
The experimental setup consists of three main parts:
- base module
- joint module
The base module includes a DC motor that rotates the joint module via a gearbox. The arm is flexibly mounted on the joint module with springs. The angle between the joint module and the arm, which is required for control, is measured by a sensor. The system's behavior can be modified by different spring positions, arm lengths and masses.
Videos: Example Rotation of the Arm to a new Target Position
In the first video you can see how the arm is rotated to a new target position without control. The arm clearly overshoots and takes time to stand still, a undesirable behaviour in practical applications.
In the second video, a control concept is applied yielding an obvious improvement. The arm now reaches the target position almost without overshooting and stops moving immediately.
Challenges for Teaching
- Mathematical modeling of the system, parameter identification
- Design of different control concepts (state space control, flatness-based feedforward control, 2-degree-of-freedom control, model predictive control)
- Investigation of the impact of model-plant mismatch
- Investigation of the influence of disturbances
Application in Practice
- Control of robot arms
- VU Fundamentals of Automatic Control (as a demonstration object)
- VO Digital Control or
- VU State Space Control of MIMO Systems or
- VU Fedback Control or
- VO & UE Adaptive and prediktive Control and one of the courses above
- VU Process Control (only for Master Chemical Process Engineering)
- VU Grundlagen der Regelungstechnik (als Demonstrationsobjekt)