approximations and simplifications are used. How-
ever, generating a safe trajectory using a simplified
vehicle model is affected by uncertainty in the ve-
hicle’s dynamics and the environment. It may lead
to suboptimal or unsafe control sequences (Borrelli
et al., 2017). Various robust MPC approaches, such
as stochastic, robust, set-theoretic, and adaptive ap-
proaches, have been proposed to overcome these
drawbacks. However, these methods can be com-
putationally expensive, challenging to implement,
or prone to instability (Magdici and Althoff, 2016;
Rawlings et al., 2017b).
Motivated by robust predictive control, we pro-
pose an approach that combines contract-based model
predictive control (CB-MPC) (Ibrahim et al., 2020;
K
¨
ogel et al., 2022) with Point-to-Point motion primi-
tives (PTP) to handle uncertainty in motion planning
while improving performance and reducing computa-
tional time complexity. The combination results in a
mixed-integer linear programming optimization prob-
lem, which generates safe, optimal, and smooth refer-
ence trajectories while avoiding obstacles even in un-
certain conditions. The simulation results show the
method’s effectiveness in maximizing vehicle perfor-
mance while handling the impact of uncertainty.
The remainder of the paper is structured as fol-
lows. Section 2 presents the problem formulation for
a single vehicle and its extension to multiple vehi-
cles. Section 3 illustrates the planning strategy and
how to integrate motion primitives in the hybrid ro-
bust receding horizon planning formulation. Section
4 presents the mathematical structure of the proposed
point-to-point motion primitives integration with a
contract-based MPC framework for real-time appli-
cations. The simulations are presented in Section 5
before concluding the paper with final remarks in Sec-
tion 6.
2 PROBLEM FORMULATION
Motion planning for autonomous vehicles in cluttered
environments aims to find a safe and optimal trajec-
tory to reach its goal while considering various con-
straints. Physical limitations of the vehicle, such as
maximum speed and acceleration, must be considered
to ensure safety, stability, and performance. The pres-
ence of static and moving obstacles in the environ-
ment limits the motion options and requires the mo-
tion planner to continuously update its plan to prevent
collisions. Due to the unpredictable motion of ob-
stacles, the uncertainty in the environment requires
the solution to be robust. Real-time motion plan-
ning presents a complex optimization problem as it
requires balancing conflicting objectives, such as task
objectives, collision avoidance, and obstacle avoid-
ance while considering the uncertainty in the envi-
ronment. This requires the solution to be computed
quickly enough to meet the real-time demands of the
vehicle’s motion. Furthermore, a new layer of com-
plexity arises when extending motion planning algo-
rithms to scenarios involving multiple vehicles navi-
gating cluttered environments. The presence of mul-
tiple vehicles increases the complexity of the opti-
mization problem. It requires the motion planner to
consider not only the avoidance of static obstacles
but also dynamic obstacles in the form of other ve-
hicles. The motion planning algorithm must handle
these complexities while satisfying the safety and sta-
bility requirements.
3 PLANNING STRATEGY
This paper addresses the challenge of devising a fea-
sible and optimal trajectory for one or more au-
tonomous vehicles (denoted as V ) to navigate from
an initial point (x
start
) to a destination (x
goal
) in a clut-
tered environment. This task involves considering un-
certainties and adhering to various constraints, includ-
ing dynamics, kinematics, and collision avoidance,
while simultaneously optimizing objectives like en-
ergy consumption and minimizing the distance to the
goal point at each time step, as illustrated in Fig. 2.
To tackle this complex problem, we propose a
robust motion planning approach that leverages a
Contract-based Model Predictive Control (CB-MPC)
framework and integrates it with the Point-to-Point
(PTP) primitives approach, as depicted in Fig. 1.
The resulting optimization problem is formulated as a
Mixed-Integer Linear Programming (MILP) problem.
MILP offers several advantages, notably its ability to
handle continuous and discrete variables. This is es-
sential for addressing challenges where discrete deci-
sions, such as mode changes due to environmental al-
terations, task objectives, or the vehicle’s capabilities,
are required (Schouwenaars et al., 2004; Schouwe-
naars, 2006).
To facilitate the understanding of the proposed ap-
proach, we will start by considering its application to
a single vehicle and present the extension to multiple
vehicles in Section 4.
3.1 Contract-Based MPC Approach
In (Ibrahim et al., 2020), a contract-based Model
Predictive Control (MPC) framework is introduced
to handle deterministic bounded uncertainty sets by
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