The requested global forces and yaw moment (Fx, Fy, and yaw moment Mz) for the heavy vehicle and how the actuators are coordinated to achieve the request is solved by using Control Allocation (CA) within the heavy vehicle’s motion control system and in the engine control system, see Fig. 1. Control allocation is an option for coordination when the system has more input signals u∈R^m than virtual signals controlled v∈R^k , k
Fig. 1. Control system including a control allocator to distribute the desired virtual control input v (global force request) to the true control input u (device request).
One promising optimization method for mapping is the constrained mixed optimization formulation
u=〖argmin‖W_u (u_des-u)‖〗_p^p+γ‖W_v (Bu-v)‖_p^p
"subject to " ▁u≤u≤¯u
where B(x,u) is the control effectiveness matrix, Wu and Wγ are diagonal weighting matrices, and γ is scalar weighting parameter to allow different priority between the mapping error Bu-v compared with error in desired signal error udes-u. When p is set to 2, the problem becomes to be a weighted least squares formulation.
Fig. 2. Reformulating Control allocation problem to standard QP formulation.
The purpose of this master thesis contains of three parts:
1. Compare real-time performance and robustness of QP solvers such as QPOases  and Volvo Group internal QP solvers, or similar found suitable for the control allocation formulation. Vary the problem size of virtual control inputs v and actuator control outputs u. The benchmarking will be conducted on dedicated computational HW that Volvo provides.
2. Propose how parallel computations of different solvers could provide higher robustness for valid solution.
3. Propose suitable watchdog solution to validate output from the control allocation function.
The thesis work will include control theory and real time optimization. Personal hobby or interest in programming real time systems is seen as benefit. The work will be carried out at Volvo Group Trucks Technology. The thesis is recommended for one or two students with control analysis profile with good mathematical skills. Thesis start: Jan 2021.
If you find this proposal interesting, send your application with CV and grades to:
Esteban Gelso – Volvo GTT
tel: +46 31 3227882
Jose Vilca – Volvo GTT
Leo Laine – Volvo GTT
tel: +46 31 323 5311
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