Development of Control Architectures for Multi-Robot Agricultural - PowerPoint PPT Presentation

Development of Control Architectures for Multi-Robot Agricultural Field Production Systems Santosh K. Pitla, Ph.D. spitla2@unl.edu Assistant Professor Department of Biological Systems Engineering University of Nebraska-Lincoln IEEE RAS Agricultural Robotics & Automation Technical Committee Webinar #013 December 2013 1

Overview  Education and Research Background  Control Architectures  Individual Robot Control Architecture (IRCA)  Multi Robot System Control Architecture (MRSCA)  Autonomous Vehicle Platform (AVP) Development  Validation of Control Architectures  Post-Doctoral Research  Future Work at UNL  Q&A 2

Education and Research Background  2000 to 2004 – BS, Mechanical Engineering, Osmania University, Hyderabad, India  Aug 2004 to May 2007 - MS, Mechanical Engineering and Biosystems and Agricultural Engineering University of Kentucky, Lexington, KY Thesis Title: Development of an Electro-Mechanical System to Identify and Map Soil Compaction  March 2007 to April 2012 – Research Engineer, Machine Systems and Automation, BAE, University of Kentucky  Jan 2008 to Jan 2012- Ph.D. Program  May 2012 to Present, Post-Doc, The Ohio State University  OCT 2013 to Present, Assistant Professor and Advanced Machinery Engineer, University of Nebraska-Lincoln 3

Control Architectures  Un-manned agricultural machines  Road blocks  Cost  Safety  Intelligence  Control architecture work is underway Autonomous Harvester Weeding Robot (Madsen (Pilarski et al., 2002) and Jakobsen, 2001) (Brooks, 1986; Arkin, 1990; Yavuz and Bradshaw, 2002; Blackmore et al., 2002; Torrie et al., 2002; and Mott et al., 2009)  Individual Robot Control Architecture  Multi-Robot System Control Architecture Citrus Fruit Harvesting Robot (Hannan et al., 2004) Agricultural Machines Control Architectures Mato Grosso,Brazil Agricultural Robots 4

Paradigm Shift (Big Vs. Small)

Paradigm Shift (Big Vs. Small) Spray material Application Variation (Luck and Pitla , 2010) 6

Individual Robot Control Architecture (IRCA) Intelligence Individual Robot Control Architecture (IRCA) 7

IRCA (continued)  Sensing Layer (SL)  Sensor Stack Array of sensors that aid the robot in learning about the unknown environment  Wireless Communication Module (WCM) Processes the information obtained wirelessly from remote or off-machine entities The SL receives the environment data obtained from the sensor stack (on-machine) and the WCM (off-machine) and passes the information to the BL for further processing and filtering

IRCA (continued)  Behavior Layer (BL)  Deliberative Behavior High level decision making processes that require planning and algorithm execution  Reactive Behavior Low level processes that do not require considerable computation but are crucial for safety and operability  By-Pass of Control The switching of the control command generation source in response to the changing environment

Individual Robot Control Architecture (IRCA) FSM I FSM IV FSM III FSM II Desired Control Commands 10

IRCA (continued) FSML Simulation (MATLAB ) Input signals created using Signal Builder (MATLAB) corresponding to the five scenarios Inputs Scenario I Scenario II Scenario III Scenario IV Scenario IV dob (m) 5 5 3 5 5 TuF 0 1 1 0 0 SA d (deg) ±0.125 ±2.5 - ±0.125 ±0.125 Five scenarios for FSM simulation SA r (deg) - - ± 5 - - Eflag 0 0 0 0 1 ReF 0 0 0 0 0 TrF 0 0 0 0 0 11

IRCA (continued) Parallel States FSML simulation SIMULINK model created for FSML simulation Mutually Exclusive States FSML created using the StateFlowChart tool Internal States Trigger conditions TuF~=1 && dob>=4 && Eflag FSM I Cruise ~=1 Slow TuF==1 && dob>=4 TuF>=0 && dob<4 && Safe Speed dob>=2 Dead dob<2 || Eflag==1 FSM II Navigate TuF>=0 && dob>=4 Safe Navigate TuF>=0 && dob<4 ReF~=1 && FSM III Lower (1) Eflag~=1&&TrF~=1&& dob>=4 ReF==1 || Eflag==1|| Raise (0) TrF==1|| dob<4 ReF~=1&&Eflag~=1&&TrF~= FSM IV ON (1) 1&&dob>=4 ReF==1||Eflag==1||TrF==1||d 12 OFF (0) ob<4

IRCA (continued) FSM Simulation Results and Discussion Active states of FSML (I to IV) in the default state Actives states in Scenario I Actives states in Scenario III 13

IRCA (continued) 14 FSM Simulation Results and Discussion FSM simulation outputs (desired control commands) Active states of FSML (I to IV) in Scenario I Scenarios Simulation Active Internal States Desired Control time (s) (FSM I to IV) Commands 4 km/h, ±0.125 o , 1, 1 Scenario I 0-10 Cruise, Navigate, Lower, ON 2 km/h, ± 2.5 o , 1, 1 Scenario II 10-20 Slow, Navigate, Lower, ON 1 km/h, ± 5 o , 0, 0 Scenario III 20-30 Safe Speed, Safe Navigate, Raise, OFF 4 km/h, ±0.125 o , 1, 1 Scenario IV 30-40 Cruise, Navigate, Lower, ON 0 km/h, ±0.125 o , 0, 0 Scenario V 40-50 Dead, Navigate, Raise, OFF

Multi-Robot System Control Architecture (MRSCA) Control Variables:  m = Mode (values: 0,1,2)  r = Role (values: 0,1,2)  c = Communication (values: 0,1) Coordination Strategy Control Variables (m, r, c) (No Cooperation) Stand Alone Behavior (0,0,0) No Cooperation Mode Stand Alone Role Transmit MRS planting in unique work zones (WZ I to WZ III) No Cooperation 15

MRSCA (continued) Coordination Control Strategy (Modest Variables (m, r, c) Cooperation) Leader (Baler) (1,1,0) Follower (Bale Spear) (1,2, 1) MRS performing baling and retrieval operations Modest Cooperation 16

MRSCA (continued) Coordination Control Strategy (Absolute Variables (m, r, c) Cooperation) Leader (Combine) (2,1, 0) Follower (GC-I, GC-II) (2,2, 1) MRS performing Harvesting Operation Absolute Cooperation 17

MRSCA (continued) 18

MRSCA (continued) Global Information Module Coordination Strategy Control Variables (m, r, c) No Cooperation (0,0,0) Modest Cooperation (1,1,0), (1,2, 1) Absolute Cooperation (2,1, 0), (2,2, 1) 19

MRSCA (continued) Hierarchy of the FSMs in GIM . GIM Coordination Wireless Role Communication Follower No Cooperation Modest Absolute Tx Rx StandAlone Leader Cooperation Cooperation Follow/ Unload Go To/ Wait Unload Load Retrieve Parallel Finite States Internal Finite States – Level I Internal Finite States – Level II 20

MRSCA (continued) Active States during Simulation in Stand Alone Mode Status Flag Definition High Low SA Raised when role of the robot is Stand Alone 1 0 Raised when the robot is performing a leader role with L1 1 0 the task Wait is active Raised when the robot is performing a leader role with L2 1 0 the Unload task active Raised when the robot is performing a follower role F1 1 0 and the task Goto is active Raised when the robot is performing a follower role F2 1 0 and the task Follow/Load is active Raised when the robot is performing a follower role F3 1 0 and the task Unload is active 21

MRSCA (Continued) StatMsgL.mat StatMsgF.mat To File To File1 Scope Scope Leader SA Follower m SA SAf m SA m r L1 L1 m r L1f L1 c r c L2 L2 r L2 L2f BD BD F1 F1 c c F1 FE FE F1f F2 BW BW F2 F2 BL F2f BL Inputs-IRCA (Follower) F3 BLf F3 F3 Inputs-IRCA (Leader) F3f Global Information Module Global Information Module Baler (Leader) Bale Retriever (Follower) BL External Wireless Input Generic Flags Definition High Low Raised when the bale is ready to be BL, BL f 1 0 retrieved Raised when the Bale Retriever is closer BD 1 0 to the hay bale to be retrieved Raised when the Bale Retriever is close FE 1 0 to the field edge for dropping of the bale Raised when the bale is loaded on the BW 1 0 22 Bale Retriever

MRSCA (Continued) Modest Cooperation (Baling – Bale Retrieving) Active states of the Baler (Leader) (b) (c) (a) Active tasks a) Go To; b) Load; and c) Unload of the Bale Retriever during the execution of the bale retrieving task 23

MRSCA (Continued) StatMsgL.mat StatMsgF1.mat To File To File1 Absolute Cooperation m SA SA m m m SA SAf1 L1 r L1 r r L1f1 L1 (Harvesting) L2 r c L2 c L2f1 c L2 F1 PS F1 F1f1 od od c F1 F2 Scope Scope F2f1 SYNCL2 F2 PS Follower1 PS F2 Leader F3 F3f1 PS SYNCL1 F3 FE FE SYNCF1 Sf1 F3 Sf1 Inputs (IRCA) Global Information Module Global Information Module InputsF1 (IRCA) Leader Follower1 StatMsgF2.mat To File2 External Wireless Input (Follower 1) SA m m SAf2 L1 r r L1f2 L2 c L2f2 c F1 F1f2 od od F2 Scope F2f2 PS Follower2 PS F3 F3f2 FE FE SYNCF2 Sf2 External Wireless Input Sf2 Global Information Module InputsF2 (IRCA ) (Follower 2) Follower2 Flags Definition High Low Raised when the Grain Carts are full with grain or PS 1 0 when the grain is available in the Combine for unloading Raised when the Grain Cart is at a desired bearing OD 1 0 (heading and location) relative to the Combine SYNCF1/S Raised when Grain Cart I wants to synchronize with 1 0 YNCL1 the Combine for the transfer of grain SYNCF2/S Raised when Grain Cart II wants to synchronize with 1 0 YNCL2 the Combine for the transfer of grain 24

MRSCA (Continued) 25

MRSCA (Continued) 26 (b) (a)

MRSCA (Continued) 27