Michael Valášek

Extended Ground-Hook - New Concept of Semi-Active Control of Truck's Suspension

SUMMARY This paper deals with the novel control concept, so called ground-hook for active and mainly semi-active suspension of vehicles with the ultimate objective to minimize the tyre-road forces and thus the road damage. The basic ground-hook concept is extended to the several variants which enable to decrease criteria of road damage as well as to increase drivers comfort for a broad range of road unevennesses. Parameters of control law are determined by the parameter optimization for generally nonlinear model. The influence and interaction of the damping rate limits and time constants of variable shock absorbers are also taken into account. The influence of implementation of more complicated truck models is also discussed.

Development of Semi-Active-Road-Friendly Truck Suspensions

Abstract Within the EC project Copernicus SADTS (Semi-Active Damping of Truck Suspensions and its Influence on Driver and Road Loads) a semi-active suspension for SKODA-LIAZ truck prototype is being developed. The objective is to decrease the dynamic road-tyre forces in order to reduce the road damage. It was necessary to find a suitable truck prototype, develop and verify a simulation model, propose different control concepts, and implement them on the truck prototype. This paper briefly describes the development stages of the project and the results finally achieved.

Overview of Coupling of Multibody and Control Engineering Tools

The role of Computer Aided Engineering in vehicle development has been significantly increased during the last decade. Specialised simulation tools became very complex, however, growing demands on complexity and particularly interdisciplinarity of vehicles and their simulation models have led to a number of approaches trying either to develop multidisciplinary simulation tools or to connect various specialised simulation tools by interfaces. This paper addresses some aspects of interconnection of the specialised simulation tools as one possibility for simulating complex mechatronic vehicle systems. It classifies the interfaces between specialised software packages in general, mentions some historical development of the interfacing and further discusses the examples of the implemented couplings between the Multibody System codes and Computer Aided Control Engineering tools. Finally, the performance of selected interfaces is compared on an example simulation of a controlled vehicle suspension.

State-space generalized predictive control for redundant parallel robots

Abstract The article deals with the design and properties of generalized predictive control (GPC) for path control of redundant parallel robots. Redundant parallel classification means redundant number of actuators, i.e., more actuators than degrees of freedom of the robot. Control of such structures suffers from several new control problems like potential inconsistency of steady state positions or nonuniqueness of control actions. The article explains classical direct derivation of GPC and its modification based on square root two-step design of control actions for solving the control problems. As an example for verification of algorithms, a prototype of a planar redundant parallel robot is used. Both design approaches are compared and several possibilities of extensions are presented for taking into consideration additional requirements, like smooth course of actuators or fulfillment of the anti-backlash condition.

STATE DERIVATIVE FEEDBACK BY LQR FOR LINEAR TIME-INVARIANT SYSTEMS

Abstract In this paper, state-derivative and especially output-derivative feedbacks for linear time-invariant systems are derived using control approach similar to linear quadratic regulator (LQR). The optimal feedback gain matrices are derived for the desired performance. This problem is always solvable for any controllable system if the open-loop system matrix is nonsingular. Explicit expression of the state-derivative gain matrix is derived. Finally, simulation results are included to show the effectiveness of the proposed approach.

Optimal control of causal differential-algebraic systems

Abstract Existence theory of Filippov–Roxin type as well as a maximum principle for optimal control problem governed by nonlinear differential–algebraic equations of index 1, or 2, or 3 are formulated and proved. The index-3 case is illustrated on mechanical descriptor systems arising in robotics.

Worlds and transformations: Supporting the sharing and reuse of engineering design knowledge

Design involves the formulation of a solution, such as a product specification, from initial requirements. Design in industrial and other contexts often involves the building and use of models that allow the designer to test hypotheses and learn from possible design decisions prior to building the physical product. The building and testing of models is a design process in its own right. Previous work in knowledge management, design rationale and the psychology of design has demonstrated that designers often vary from prescriptive methodologies of the design process and have problems appropriately describing their design activity in order to support design collaboration and the reuse of design artefacts. Drawing on this work, we support design collaboration and reuse structured according to key transformational episodes in the design process and the design artefacts they produce. To support this, we characterise the design task as progressing through a series of worlds, each comprising its own concepts and vocabulary, and supported by its own design tools. The design process can then be described in terms of important transformations that are made from one world to the next. This allows a targeted approach to rationale capture integrated with work practice and associated with products of the design process. This approach has been successfully deployed and tested in two industrial engineering companies. Findings included improved collaboration in design teams, effective reuse and improved training for new members of the design team. This work has more general implications for the development of design rationale methods and tools to support the design process.

DYNAMIC MODEL OF TRUCK FOR SUSPENSION CONTROL

Abstract This paper presents the modelling of heavy duty vehicle prototype for a semi-active suspension design. Two basic models have been developed - the model of a passive vehicle and the model of a vehicle equipped with controllable shock absorbers. The models serve for evaluation of several proposed control schemes. The identification and verification experiments, which has been provided on the truck are described as well as the software tools used in the process of simulation.

Evaluation of Dynamic Capabilities of Machines and Robots

The paper deals with the formulation and thesolution of the global dynamic problem for multibody systemsgenerally described by redundant coordinates (DAE equations) andwith a redundant number of actuators.Within the dynamics of multibody systems two basic well-known problems have been investigated: the solution of direct dynamicsand the solution of inverse dynamics. Both of these problems enableus to solve in each time instant the relation between the motiondescribed by positions, velocities, accelerations and the actingforces. However, such solutions obtained in isolated timeinstants do not provide us with the global overview about thedynamic capabilities of a mechanical system, i.e. about theaccessible motion described by accessible positions, accessiblevelocities, accessible accelerations and the required (given)forces. Thus, besides the two basic dynamical problems there isa third one: the global dynamic problem.The formulation of the global dynamic problem, the generalmethods for its solution and the specific methods for itssolution for robots and manipulators are included.

A Direct Algorithm for Pole Placement by State-derivative Feedback for Single-input Linear Systems

This paper deals with the direct solution of the pole placement problem for single-input linear systems using state-derivative feedback. This pole placement problem is always solvable for any controllable systems if all eigenvalues of the original system are nonzero. Then any arbitrary closed-loop poles can be placed in order to achieve the desired system performance. The solving procedure results in a formula similar to the Ackermann formula. Its derivation is based on the transformation of a linear single-input system into Frobenius canonical form by a special coordinate transformation, then solving the pole placement problem by state derivative feedback. Finally the solution is extended also for single-input time-varying control systems. The simulation results are included to show the effectiveness of the proposed approach.