Name
Abstract | ||
|---|---|---|
This paper presents a comprehensive comparative study of several non- linear controllers for stabilisation of the under actuated unstable nonlinear object known as the Acrobot in the literature. The object is a two DOF robot arm only actuated at the elbow. The study compares several control algorithms from the liter- ature and a new algorithm developed during the study. The comparison is based on both simulation and real experiments for all controllers. During the last decade the Acrobot has been used as example object in several studies of non linear control. There are several reasons for this. First of all having only two degrees of freedom the complexity of the equations of motion is low enough to allow analytical results of the proposed non linear methods and in spite of the low order of the object the non linearities are very decisive for the behavior which means that clas- sical LQR-controllers designed using a linearization of the object have a very limited region of stability around the linearization point. Secondly stabilizing the Acrobot can be seen as a prestudy to bipedal walking machines as it simulates balancing of a person having no feet (standing on stilts) using only hip movements. As mentioned above the Acrobot has been the subject of several studies but most of these present only one algorithm and often only theoretical or simulation results. The main purpose of this study is to perform systematic comparison of several algorithms for stabilisa- tion of the acrobot using both simulation and real experiments. The importance of testing different algorithms on the same physical acrobot is emphasized by the fact that the actual configuration of the acrobot (lengths and masses of the two arms) has great influence of the performance of different controllers thus making it difficult to compare results obtained on different physical systems directly. In some configura- tions the performance of a linear controller is equal to the performance of some non linear controllers. The outline of the paper is as follows. In section 2 the basic equations for the acrobot are given and the difference between torque control and acceleration control is explained. In section 3 a short description of the five investigated control algo- rithms is presented along with simulation results for the ideal Acrobot i.e. simulation without physical constraints of the actuator and measuring systems and feedback from all states. Section 5 contains simulations of the full system including the dynamics and constraints of the actuator and quantization of the angle measurements and sampling of the digital controller. It also contains the measurements on the real system. Section 6 gives a description of the experimental setup and describes the implementation of the acceleration control. |
Year | DOI | Venue |
|---|---|---|
2000 | 10.1007/3-540-45118-8_48 | ISER |
Keywords | Field | DocType |
actuated unstable nonlinear object,digital controller,robot arm,equation of motion,measurement system,non linear control | Control algorithm,Acceleration control,Robotic arm,Control theory,Nonlinear system,Control theory,Simulation,Automatic control,Control engineering,Engineering | Conference |
Volume | ISSN | ISBN |
271 | 0170-8643 | 3-540-42104-1 |
Citations | PageRank | References |
1 | 0.41 | 3 |
Authors | ||
3 | ||
Name | Order | Citations | PageRank |
|---|---|---|---|
| Nils A. Andersen | 1 | 28 | 6.67 |
| Lars Skovgaard | 2 | 1 | 0.41 |
| Ole Ravn | 3 | 256 | 54.31 |