ERC 2020 Preliminary Report

Introduction

Purpose of the document

Purpose of this document is to create core documentation of Orion III rover for European Rover Challenge competition

Scope of the document

This document contains
  1. Technical requirements definitions, with ways to fullfill them and test plans
  2. Project assumptions - compared with proposal, if changed.
  3. Technologies which are, or will be, used in project
  4. Pre-final system breakdown structure
  5. Safety systems description
  6. Preliminary financial planning
  7. Present problems and issues, and how we are planning to solve them

Additionally, pre-final radio frequency form will be added to final preliminary report as appendix.

Acronyms

Acronym matrix
Acronym Full form Description
AR Acceptance Review A phase in which the product is verified on customer’s infrastructure
COTS Commercial, Off-The-Shelf A product that can be purchased/obtained freely in the market and utilized in a project
CDR Critical Design Review A development phase in which the project is reviewed critically, ideally by the external entity. It is to check compilance with requirements and test a so-far developed device.
FOV Field of View An area that is perceived by a camera
HMI Human-Machine Interface Any interface that facilitates sending/receiving commands to/from software or hardware
SW Software A set of commands to be executed on a computer, expressed in a human-readable format
SFR Simple Fetching Rover A type of a Mars rover that supposed to quickly transport an object, e.g. a boxed specimen, to the ground control

Terms and definitions

Terms and definitions
Term Definition
Ground control A place where a team can send commands to the rover and receive feedback data.
Rover A remotely controlled robotic platform.

Applicable documents

Applicable document
Reference ID Title Short document description
[ERC-2020] European Rover Challenge 2020 - STUDENT rules Rules and formula of ERC2020

Technical requirements definitions

Mechanics

General requirements
Abbreviation Description [ERC-2020] page Test Method Assumptions/solutions/testing.
REQ-MECH-GEN-001 Environmental resistance (mostly dust and humidity) 6 Review Proper shell will be prepared. It will be able to withstand the elements.
Chassis requirements
Abbreviation Description [ERC-2020] page Test Method Assumptions/solutions/testing.
REQ-MECH-CHAS-001 Driving on dry, loose surface (sand, gravel) 5, 6, 17, 19, 22, 23 Test The wheels will have proper tread. The rover will be tested on multiple surfaces including sand, clay, gravel.
REQ-MECH-CHAS-002 Driving on hard, dry sufrace (concrete, grass) 5, 6, 17, 19, 22, 23 Test The tread will be made from slightly elastic material. The rover will be tested on multiple surfaces including concrete, tiles, synthetic paneling, grass.
REQ-MECH-CHAS-003 Rotation in place 5, 6, 17, 19, 22, 23 Test The rover will be steered differentially. Tests will include driving in an arc, rotating in place and maneuvers in tight spaces.
REQ-MECH-CHAS-004 Driving onto an inclined surface (around 30-40 degrees) 5, 6, 17, 19, 22, 23 Test The rover will have a low center of gravity and significant torque on the wheels. The rover will be driven around the university campus which is full of steep hills, depressions and moderately hard terrain.
REQ-MECH-CHAS-005 Driving parallel to an inclined surface, having part of chassis slopped (by around 30-40 degrees) 5, 6, 17, 19, 22, 23 Test The chassis will be wide enough to prevent tipping over. The rover will be driven around the university campus which is full of steep hills, depressions and moderately hard terrain.
REQ-MECH-CHAS-006 Driving over off-road faults (minor bumps and holes) 5, 6, 17, 19, 22, 23 Test The treading will be sufficient. The chassis will be able to adapt to the shape of the terrain. The rover will be driven over small rocks, sharp small inclines, onto and down from curbs and stairs.

Electronics

Manipulator requirements
Abbreviation Description [ERC-2020] page
REQ-ELEC-MAN-001 Measurement of voltage between 1V and 24V with 0.5V accuracy 21, 38

Safety

Safety requirements
Abbreviation Description [ERC-2020] page
REQ-SAFE-STOP-001 Accesible red emergency stop button 7
REQ-SAFE-STOP-002 Battery cutoff 7
REQ-SAFE-STOP-003 Mechanical robustness of button 7
REQ-SAFE-BATT-001 Battery voltage and temperature measurement 7
REQ-SAFE-BATT-002 Mitigation of fire risk 7
REQ-SAFE-INDI-001 Rover equipped with yellow, orange or red indicator lamp visible from at least 10m 7
REQ-SAFE-INDI-002 Indicator light must activate 5 seconds before any rover movement 7
REQ-SAFE-AUTO-001 Autonomous operation must activate 5 seconds after issuing the command 7
REQ-SAFE-AUTO-002 Rover must safely handle command overflow 7

Communication

Communication requirements
Abbreviation Description [ERC-2020] page
REQ-COMM-BAND-001 The system must use legally available frequencies 7
REQ-COMM-BAND-002 The system must allow band switching 9
REQ-COMM-FORM-001 The team must provide an RF form with relevant information 10

Technical requirements fullfillment plan

Test plans

Used technologies

Chassis

We have decided to use standard 4-wheel chassis made of aluminum and policarbonate sheets, which gave us rigid and relatively light base for the rest of rover. Every wheel has it’s own BLDC motor taken from electric hoverboard. This ensures formidable torque, speed control and high efficiency. The speed of the rover is limited by software.

Chasis is splitten into two separate, independent parts, connected to each other with a shaft. This kind of solution made whole chassis much more flexible in terms of overcoming bumps in the field, ensuring that at least two wheels at the same time will have traction.

Pre-final system breakdown structure

Safety systems description

Preliminary financial planning

Present problems and issues

Present problems and potential solutions
Problem Descrption Solution
Management issues There is not enough specialists in the project to effectively push it forward, and make constant progress. We have a lot of rookies which want to learn, but not enough time and people to teach them everything they need to know in order to work in project. We need to find and recruit more specialists, with particular emphasis on programmers and electronics.
Hardware stability issues We are still not able to run all the tests properly, because our hardware (mostly power drivers) is failing in random places due to the bad engineering decisions made because of a hurry. Re-create hardware the right way, utilizing PCB, COTS parts, and minimizing “garage engineering” factor to necessary miniumum. Regular testing is also required.