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Centimeter-Level Accuracy Path Tracking Control of Tractors and Actively Steered Implements

  • Accurate path tracking control of tractors became a key technology for automation in agriculture. Increasingly sophisticated solutions, however, revealed that accurate path tracking control of implements is at least equally important. Therefore, this work focuses on accurate path tracking control of both tractors and implements. The latter, as a prerequisite for improved control, are equipped with steering actuators like steerable wheels or a steerable drawbar, i.e. the implements are actively steered. This work contributes both new plant models and new control approaches for those kinds of tractor-implement combinations. Plant models comprise dynamic vehicle models accounting for forces and moments causing the vehicle motion as well as simplified kinematic descriptions. All models have been derived in a systematic and automated manner to allow for variants of implements and actuator combinations. Path tracking controller design begins with a comprehensive overview and discussion of existing approaches in related domains. Two new approaches have been proposed combining the systematic setup and tuning of a Linear-Quadratic-Regulator with the simplicity of a static output feedback approximation. The first approach ensures accurate path tracking on slopes and curves by including integral control for a selection of controlled variables. The second approach, instead, ensures this by adding disturbance feedforward control based on side-slip estimation using a non-linear kinematic plant model and an Extended Kalman Filter. For both approaches a feedforward control approach for curved path tracking has been newly derived. In addition, a straightforward extension of control accounting for the implement orientation has been developed. All control approaches have been validated in simulations and experiments carried out with a mid-size tractor and a custom built demonstrator implement.
Author:Roland Werner
URN (permanent link):urn:nbn:de:hbz:386-kluedo-44013
Publisher:Verlag Dr. Hut
Place of publication:München
Advisor:Steffen Müller, Jörg Seewig
Document Type:Doctoral Thesis
Language of publication:English
Publication Date:2015/05/21
Date of first Publication:2015/05/21
Publishing Institute:Technische Universität Kaiserslautern
Granting Institute:Technische Universität Kaiserslautern
Acceptance Date of the Thesis:2015/05/21
Date of the Publication (Server):2016/06/22
Tag:Extended Kalman Filter; Linear-Quadratic-Regulator; actively steered implement; dynamic model; kinematic model; output feedback approximation; path tracking; tractor; wheel side-slip estimation
GND-Keyword:controller; dynamic; filter; implement; kalman; kinematic; model; optimal; path; tracking; tractor
Number of page:XXVIII, 173 S.
Source:Verlag Dr. Hut, 2015
Faculties / Organisational entities:Fachbereich Maschinenbau und Verfahrenstechnik
CCS-Classification (computer science):J. Computer Applications / J.2 PHYSICAL SCIENCES AND ENGINEERING / Engineering
DDC-Cassification:6 Technik, Medizin, angewandte Wissenschaften / 600 Technik
6 Technik, Medizin, angewandte Wissenschaften / 620 Ingenieurwissenschaften und Maschinenbau
MSC-Classification (mathematics):93-XX SYSTEMS THEORY; CONTROL (For optimal control, see 49-XX) / 93Cxx Control systems / 93C83 Control problems involving computers (process control, etc.)
93-XX SYSTEMS THEORY; CONTROL (For optimal control, see 49-XX) / 93Cxx Control systems / 93C85 Automated systems (robots, etc.) [See also 68T40, 70B15, 70Q05]
Licence (German):Zweitveröffentlichung