Solving a Minimum Lap Time Problem (MLTP), under the constraints stemming from a
race car’s driving dynamics, can be considered to be state of the art.
Nevertheless, when dealing with electric race vehicles as in Formula E or the
Roborace competition, solving an MLTP is not enough to form an appropriate
competition strategy: Maximum performance over the entire race can only be
achieved by an optimization horizon spanning all the subsequent laps of a race.
This results in a Minimum Race Time Problem (MRTP). To solve this, the
thermodynamic and energetic limitations of the electric powertrain components
must be taken into account, as exceeding them leads to safety shutdowns.
Therefore, we present an Optimal Control Problem (OCP) to calculate an Energy
Strategy (ES) for electric race cars, which contain physically detailed
descriptions of its powertrain components. Leveraging a Sequential Quadratic
Programming (SQP) solver, the OCP can be solved numerically in real time. This
enables the ES to be recalculated during a race. As a consequence, powertrain
overheating can be omitted and the limited amount of stored battery energy
utilized as efficiently as possible. Simultaneously, the race can be completed
in minimum time.
