  In this paper, we theoretically develop and numerically validate an
asymmetric linear bilateral control model (LBCM). The novelty of the asymmetric
LBCM is that using this model all the follower vehicles in a platoon can adjust
their acceleration and deceleration to closely follow a constant desired time
gap to improve platoon operational efficiency while maintaining local and
string stability. We theoretically analyze the local stability of the
asymmetric LBCM using the condition for asymptotic stability of a linear
time-invariant system and prove the string stability of the asymmetric LBCM
using a space gap error attenuation approach. Then, we evaluate the efficacy of
the asymmetric LBCM by simulating a closely coupled cooperative adaptive cruise
control (CACC) platoon of fully automated trucks in various non-linear
acceleration and deceleration states. We choose automated truck platooning as a
case study since heavy-duty trucks experience higher delays and lags in the
powertrain system, and limited acceleration and deceleration capabilities than
passenger cars. To evaluate the platoon operational efficiency of the
asymmetric LBCM, we compare the performance of the asymmetric LBCM to a
baseline model, i.e., the symmetric LBCM, for different powertrain delays and
lags. Our analyses found that the asymmetric LBCM can handle any combined
powertrain delays and lags up to 0.6 sec while maintaining a constant desired
time gap during a stable platoon operation, whereas the symmetric LBCM fails to
ensure stable platoon operation as well as maintain a constant desired time gap
for any combined powertrain delays and lags over 0.2 sec. These findings
demonstrate the potential of the asymmetric LBCM in improving platoon
operational efficiency and stability of an automated truck platoon.
