Wubing B Qin | University of Michigan (original) (raw)
Papers by Wubing B Qin
2014 American Control Conference, 2014
In this paper we investigate the concept of connected cruise control (CCC) where vehicles rely on... more In this paper we investigate the concept of connected cruise control (CCC) where vehicles rely on ad-hoc wireless vehicle-to-vehicle (V2V) communication to control their longitudinal motion. While V2V communication potentially allows vehicles to build detailed knowledge about the traffic environment, intermittencies and packet drops introduce stochastic delays into the communication channels that make control very challenging. Moreover, while communication and control occurs in discrete time, vehicle dynamics still takes place in continuous time. We convert the dynamics to discrete time and analyze the effects of stochastic delays on vehicular platoons. We derive plant and string stability conditions for the mean dynamics and show how the stable regimes shrink when the sampling time or the packet drop ratio increases. Our results have important implications regarding safety and efficiency of connected vehicle systems.
2014 American Control Conference, 2014
IEEE Transactions on Intelligent Transportation Systems, 2017
In this paper we investigate connected cruise control (CCC) where vehicles rely on ad-hoc wireles... more In this paper we investigate connected cruise control (CCC) where vehicles rely on ad-hoc wireless vehicle-to-vehicle (V2V) communication to control their longitudinal motion. Intermittencies and packet drops in communication channels are shown to introduce stochastic delays in the feedback loops. Sufficient conditions for almost sure stability of equilibria are derived by analyzing the mean and covariance dynamics. In addition, the concept of nσ string stability is proposed to characterize the input-output response in steady state. The stability results are summarized using stability charts in the plane of the control gains and we demonstrate that the stable regimes shrink when the sampling time or the packet drop ratio increases. The mathematical tools developed allow us to design controllers that can achieve plant stability and string stability in connected vehicle systems despite the presence of stochastically varying delays in the control loop.
In this paper, we investigate a vehicular string traveling on a single lane, where vehicles use ... more In this paper, we investigate a vehicular string traveling on a single lane, where vehicles use connected cruise control to regulate their longitudinal motion based on data received from other vehicles via wireless vehicle-to-vehicle communication. Assuming digital controllers, the sample-and-hold units introduce time-periodic time delays in the control loops and the delays increase when data packets are lost. We investigate the effect of packet losses on plant and string stability while varying the control gains and determine the minimum achievable time gap below which stability cannot be achieved. We propose two predictor feedback control strategies that overcome the destabilizing effect of the time delay caused by the sample-and-hold unit and packet losses.
In this paper large connected vehicle systems are analyzed where vehicles utilize vehicle-to-vehi... more In this paper large connected vehicle systems are analyzed where vehicles utilize vehicle-to-vehicle (V2V) communication to control their longitudinal motion. It is shown that packet drops in communication channels introduce stochastic delay variations in the feedback loops. Scalable methods are developed to evaluate stability and disturbance attenua-tion while utilizing the mean, second moment, and covariance dynamics in open chain and closed ring configurations. The stability results are summarized using stability diagrams in the plane of the control parameters while varying the packet delivery ratio and the number of vehicles. Also, the relationship between the stability of different configurations is characterized. The results emphasize the feasibility of V2V communication-based control in improving traffic flow. Published by Elsevier Ltd. 1. Introduction The past decades witnessed a worldwide increase in the number of vehicles on the road, bringing major concerns about traffic congestions (Schrank et al., 2015). The large reaction time and limited perception range of human drivers make them unable to maintain smooth traffic flow and may trigger stop-and-go traffic jams while reacting to unexpected events (Orosz et al., 2009, 2010). On the other hand, advanced driver assistant systems (ADAS) can be used to improve the longitudinal control of vehicles. Although such technologies typically target at the enhancement of safety and driving comfort, they have an enormous potential in improving the efficiency of large scale traffic systems. For example, adaptive cruise control (ACC) can be used to maintain a velocity-dependent inter-vehicle distance based on range sensors (radar or lidar) (Shladover, 1991; Ioannou and Chien, 1993; Rajamani and Zhu, 2002). It was demonstrated in (Werf et al., 2002; Davis, 2007) that due to faster and more accurate sensing abilities ACC may have a positive impact on traffic flow when the penetration rate of ACC vehicles is high enough. However, due to the high cost of range sensors and the perception limitation within the line of sight, this technology is still not widely available. To overcome the limitations, it was proposed to augment ACC with wireless V2V communication. This can allow vehicles to monitor the kinematic properties of other vehicles, even those beyond the line of sight, and they may utilize such information in their controllers to improve their safety and fuel economy and to mitigate traffic jams. In the US dedicated short range communication (DSRC)
To improve the ride quality in connected vehicle platoons, information about the motion of the l... more To improve the ride quality in connected vehicle platoons,
information about the motion of the leader can be transmitted
using vehicle-to-vehicle (V2V) communication and such information can be incorporated in the controllers of the following
vehicle. However, according to the current V2V standards, dedicated short range communication (DSRC) devices transmit information every 100 ms which introduces time delays into the
control loops. In this paper we study the effects of these time delays on the dynamics of vehicle platoons subject to digital control and derive conditions for plant stability and string stability. It is shown that when the time delay exceeds a critical value, no gain combination can stabilize the system. Our results have important implications on connected vehicle design.
In this paper we investigate the concept of connected cruise control (CCC) where vehicles rely o... more In this paper we investigate the concept of connected
cruise control (CCC) where vehicles rely on ad-hoc
wireless vehicle-to-vehicle (V2V) communication to control their
longitudinal motion. While V2V communication potentially
allows vehicles to build detailed knowledge about the traffic
environment, intermittencies and packet drops introduce
stochastic delays into the communication channels that make
control very challenging. Moreover, while communication and
control occurs in discrete time, vehicle dynamics still takes
place in continuous time. We convert the dynamics to discrete
time and analyze the effects of stochastic delays on vehicular
platoons. We derive plant and string stability conditions for
the mean dynamics and show how the stable regimes shrink
when the sampling time or the packet drop ratio increases.
Our results have important implications regarding safety and
efficiency of connected vehicle systems.
This paper provides analytical results regarding the stability of linear discrete-time systems w... more This paper provides analytical results regarding
the stability of linear discrete-time systems with stochastic
delays. Necessary and sufficient stability conditions are derived
by using the second moment dynamics which can be used
to draw stability charts. The results are applied to a simple
connected vehicle system where the stability regions are compared
to those given by the mean dynamics. Our results reveal
some fundamental limitations of connected cruise control which
becomes more significant as the packet drop ratio increases.
2014 American Control Conference, 2014
In this paper we investigate the concept of connected cruise control (CCC) where vehicles rely on... more In this paper we investigate the concept of connected cruise control (CCC) where vehicles rely on ad-hoc wireless vehicle-to-vehicle (V2V) communication to control their longitudinal motion. While V2V communication potentially allows vehicles to build detailed knowledge about the traffic environment, intermittencies and packet drops introduce stochastic delays into the communication channels that make control very challenging. Moreover, while communication and control occurs in discrete time, vehicle dynamics still takes place in continuous time. We convert the dynamics to discrete time and analyze the effects of stochastic delays on vehicular platoons. We derive plant and string stability conditions for the mean dynamics and show how the stable regimes shrink when the sampling time or the packet drop ratio increases. Our results have important implications regarding safety and efficiency of connected vehicle systems.
2014 American Control Conference, 2014
IEEE Transactions on Intelligent Transportation Systems, 2017
In this paper we investigate connected cruise control (CCC) where vehicles rely on ad-hoc wireles... more In this paper we investigate connected cruise control (CCC) where vehicles rely on ad-hoc wireless vehicle-to-vehicle (V2V) communication to control their longitudinal motion. Intermittencies and packet drops in communication channels are shown to introduce stochastic delays in the feedback loops. Sufficient conditions for almost sure stability of equilibria are derived by analyzing the mean and covariance dynamics. In addition, the concept of nσ string stability is proposed to characterize the input-output response in steady state. The stability results are summarized using stability charts in the plane of the control gains and we demonstrate that the stable regimes shrink when the sampling time or the packet drop ratio increases. The mathematical tools developed allow us to design controllers that can achieve plant stability and string stability in connected vehicle systems despite the presence of stochastically varying delays in the control loop.
In this paper, we investigate a vehicular string traveling on a single lane, where vehicles use ... more In this paper, we investigate a vehicular string traveling on a single lane, where vehicles use connected cruise control to regulate their longitudinal motion based on data received from other vehicles via wireless vehicle-to-vehicle communication. Assuming digital controllers, the sample-and-hold units introduce time-periodic time delays in the control loops and the delays increase when data packets are lost. We investigate the effect of packet losses on plant and string stability while varying the control gains and determine the minimum achievable time gap below which stability cannot be achieved. We propose two predictor feedback control strategies that overcome the destabilizing effect of the time delay caused by the sample-and-hold unit and packet losses.
In this paper large connected vehicle systems are analyzed where vehicles utilize vehicle-to-vehi... more In this paper large connected vehicle systems are analyzed where vehicles utilize vehicle-to-vehicle (V2V) communication to control their longitudinal motion. It is shown that packet drops in communication channels introduce stochastic delay variations in the feedback loops. Scalable methods are developed to evaluate stability and disturbance attenua-tion while utilizing the mean, second moment, and covariance dynamics in open chain and closed ring configurations. The stability results are summarized using stability diagrams in the plane of the control parameters while varying the packet delivery ratio and the number of vehicles. Also, the relationship between the stability of different configurations is characterized. The results emphasize the feasibility of V2V communication-based control in improving traffic flow. Published by Elsevier Ltd. 1. Introduction The past decades witnessed a worldwide increase in the number of vehicles on the road, bringing major concerns about traffic congestions (Schrank et al., 2015). The large reaction time and limited perception range of human drivers make them unable to maintain smooth traffic flow and may trigger stop-and-go traffic jams while reacting to unexpected events (Orosz et al., 2009, 2010). On the other hand, advanced driver assistant systems (ADAS) can be used to improve the longitudinal control of vehicles. Although such technologies typically target at the enhancement of safety and driving comfort, they have an enormous potential in improving the efficiency of large scale traffic systems. For example, adaptive cruise control (ACC) can be used to maintain a velocity-dependent inter-vehicle distance based on range sensors (radar or lidar) (Shladover, 1991; Ioannou and Chien, 1993; Rajamani and Zhu, 2002). It was demonstrated in (Werf et al., 2002; Davis, 2007) that due to faster and more accurate sensing abilities ACC may have a positive impact on traffic flow when the penetration rate of ACC vehicles is high enough. However, due to the high cost of range sensors and the perception limitation within the line of sight, this technology is still not widely available. To overcome the limitations, it was proposed to augment ACC with wireless V2V communication. This can allow vehicles to monitor the kinematic properties of other vehicles, even those beyond the line of sight, and they may utilize such information in their controllers to improve their safety and fuel economy and to mitigate traffic jams. In the US dedicated short range communication (DSRC)
To improve the ride quality in connected vehicle platoons, information about the motion of the l... more To improve the ride quality in connected vehicle platoons,
information about the motion of the leader can be transmitted
using vehicle-to-vehicle (V2V) communication and such information can be incorporated in the controllers of the following
vehicle. However, according to the current V2V standards, dedicated short range communication (DSRC) devices transmit information every 100 ms which introduces time delays into the
control loops. In this paper we study the effects of these time delays on the dynamics of vehicle platoons subject to digital control and derive conditions for plant stability and string stability. It is shown that when the time delay exceeds a critical value, no gain combination can stabilize the system. Our results have important implications on connected vehicle design.
In this paper we investigate the concept of connected cruise control (CCC) where vehicles rely o... more In this paper we investigate the concept of connected
cruise control (CCC) where vehicles rely on ad-hoc
wireless vehicle-to-vehicle (V2V) communication to control their
longitudinal motion. While V2V communication potentially
allows vehicles to build detailed knowledge about the traffic
environment, intermittencies and packet drops introduce
stochastic delays into the communication channels that make
control very challenging. Moreover, while communication and
control occurs in discrete time, vehicle dynamics still takes
place in continuous time. We convert the dynamics to discrete
time and analyze the effects of stochastic delays on vehicular
platoons. We derive plant and string stability conditions for
the mean dynamics and show how the stable regimes shrink
when the sampling time or the packet drop ratio increases.
Our results have important implications regarding safety and
efficiency of connected vehicle systems.
This paper provides analytical results regarding the stability of linear discrete-time systems w... more This paper provides analytical results regarding
the stability of linear discrete-time systems with stochastic
delays. Necessary and sufficient stability conditions are derived
by using the second moment dynamics which can be used
to draw stability charts. The results are applied to a simple
connected vehicle system where the stability regions are compared
to those given by the mean dynamics. Our results reveal
some fundamental limitations of connected cruise control which
becomes more significant as the packet drop ratio increases.