Controller design for string stable heterogeneous vehicle strings

Abstract

The spacing errors of a string stable, homogeneous vehicle string attenuate uniformly down the vehicle chain. This result is useful for implementing vehicle formation control because it provides a guideline for the proper intervehicle spacing. In the heterogeneous case, the differing dynamics of the vehicles means the spacing errors do not attenuate or amplify uniformly down the vehicle chain, regardless of whether the formation is string stable or not. Results from heterogeneous string stability analysis are presented and used to construct a controller design procedure that gives string stability and robustness to external disturbances for heterogeneous vehicle strings. The proper intervehicle spacing needed for nominal safety is determined. The resulting controller is simulated to demonstrate its effectiveness. It is shown that string stability can be achieved for heterogeneous vehicle strings of arbitrary length and arbitrary vehicle type ordering.

Cooperative adaptive cruise control, design and experiments

“…String stability is extensively discussed in literature. As a result, various definitions are present, see, e.g., [4], [6], [7], [9], [10], [14]. The main ambiguity concerns the signals to consider.…”

“…1 [9]. Furthermore, heterogeneous traffic is considered, i.e., vehicles with different characteristics [4], [10], and delay in the communicated signal is taken into account [6], [7], [11]. Finally, the communication will be implemented as a feedforward signal.…”

Leader and Predecessor Following Robust Controller Synthesis for String Stable Heterogeneous Vehicle Platoons

“…The simplest approach to obtain leader and predecessor following controller is to excite controllerK i by the linear combination of the inputs received from the leader and the preceding vehicle, respectively, as proposed by Shaw and Hedrick (2007a) …”

“…In the present paper the results by Shaw and Hedrick (2007a) are generalized in a number of ways. General definitions for heterogeneous string stability are formulated in Section 2.…”

“…In the majority of the papers, string stability of vehicle formations are analyzed or controllers are designed with the assumption of specific and common control laws. Some exceptions in the field of analysis are by Middleton and Braslavsky (2010), Lestas and Vinnicombe (2006), Seiler et al (2004), Barooah and Hespanha (2005), and in the field of control synthesis by Shaw and Hedrick (2007a).…”