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Editorials

Frequently asked questions about ANSI/CSA 22.2 No. 336 for Robotic Engineers

by Jonathan Moore
Exida Consulting LLC

Frequently asked questions about ANSI/CSA 22.2 No. 336 for robotic engineers

On January 5th CSA Group published the first edition of Particular requirements for rechargeable battery-operated commercial robotic floor treatment machines with traction drives.  CSA 22.2 - 336 is a National Standard of Canada.

Why do I care?

If you are a robotics engineer working for a company planning to sell in North America, floor treatment machines including sweeping, scrubbing, wet or dry pickup, polishing, application of wax, sealing products, and powder-based detergents or shampooing then this standard has important test requirements for you.

Is it a legal requirement?

It is not.

Why do I care then?

Occupational Safety and Health Act in the USA and the Canadian Electric Code are legal requirements. All electrically controlled devices or systems in the USA must be approved.

What is in the standard?

Many of the requirements apply to both manual and robotic machines including such things like electrical safety, battery safety, mechanical strength and construction.

How do I get a copy?

The standard is available from the CSA Group website at or by searching for “336-17” on the CSA Group Store. Please support them and consider licensing a copy of this document. The price is very reasonable at ~100 USD and the CSA do valuable work.

I’ve bought a copy CSA 336, it references 26 other standards do I have to buy all of those too and how much will that cost?

This table lists the standards directly referenced by CSA 336. In North American they are available for purchase from ANSI for approximately $10,000[1].

Standard

Title

NFPA 70

National Electrical Code

UL 1012 

Standard for Power Units Other Than Class 2

UL 1310

Standard for Class 2 Power Units

UL 1564

Standard for Industrial Battery Chargers

UL 2595

General requirements for battery-powered appliances

UL 583

Standard for Electric-Battery-Powered Industrial Trucks

IEC 60204-1

Safety of machinery – Electrical equipment of machines – Part 1: General requirements

IEC 60335-1

Household and similar electrical appliances — Safety — Part 1: General requirements

IEC 60335-2-29

Household and similar electrical appliances - Safety - Part 2-29: Particular requirements for battery chargers

IEC 60335-2-69

Hazardous dust

IEC 60335-2-72

Household and similar electrical appliances – Safety – Part 2-72: Particular requirements for floor treatment machines with or without traction drive, for commercial use

IEC 60417

Graphical symbols for use on equipment

IEC 60529

Degrees of protection provided by enclosures

IEC 60825-1

Safety of laser products - Part 1: Equipment classification and requirements

IEC 61000

Electromagnetic compatibility (EMC)

IEC 61032

Protection of persons and equipment by enclosures - Probes for verification

IEC 61496-2

Safety of machinery – Electro-sensitive protective equipment – Part 2: Particular requirements for equipment using active opto-electronic protective devices (AOPDs)

IEC 62061

Safety of machinery – Functional safety of safety-related electrical, electronic and programmable electronic control systems

IEC 62471

Photobiological safety of lamps and lamp systems

IEC 62826

Surface cleaning appliances — Floor treatment machines with or without traction drive, for commercial use — Methods of measuring the performance

ISO 13482

Robots and robotic devices — Safety requirements for personal care robots

ISO 13849-1

Safety of machinery — Safety-related parts of control systems — Part 1: General principles for design

ISO 13857

Safety of machinery -- Safety distances to prevent hazard zones being reached by upper and lower limbs

ISO 18646-1

Robotics - Performance criteria and related test methods for service robots - Part 1: Locomotion for wheeled robots

ISO 7000

Graphics symbols for use on equipment

ISO 8373

Robots and robotic devices — Vocabulary

 

How am I supposed to understand all of those standards?

Most of these standards are very easy to understand and adopt and likely already part of your design or managed by your suppliers. Four of them are Functional Safety Standards and require specialist knowledge to implement correctly.

Standard

Title

IEC 60335-1

Household and similar electrical appliances — Safety — Part 1: General requirements

IEC 62061

Safety of machinery – Functional safety of safety-related electrical, electronic and programmable electronic control systems

ISO 13482

Robots and robotic devices — Safety requirements for personal care robots

ISO 13849-1

Safety of machinery — Safety-related parts of control systems — Part 1: General principles for design

 

There are 11 clauses that govern the automated floor treatment functions. These clauses define acceptance criteria for tests which if satisfied would demonstrate a minimum level of performance. The clauses have requirements relating to the following:

  • Functional safety of control system functions
  • Stopping distance, slope holding
  • Speed limits in open and confined space environments
  • Reference test obstacles and detection requirements
  • Starting, restarting and reset

Let’s look at these requirements in some more detail.

Functional Safety

Each of these standards refers to IEC 61508 Functional safety of electrical / electronic / programmable electronic safety-related systems. IEC 61508 is a multi-part standard that has requirements not only on the design but on the design process itself and the people conducting the engineering as well as the people checking or testing your work. IEC 61508 has requirements for both hardware and software.

I’m a systems engineer / architect where should I begin?

CSA 336 identifies six safety-critical functions and establishes the minimum safety integrity level required of the subsystems implementing these functions. It’s inevitable that automated machines like this will use a combination of hardware actuators and motors, programmable controllers and software, and sensors to implement these safety-critical functions.  Here’s a diagram showing a typical scope for the safety functions. You’ll need design your own architecture and establish FIT targets for each of the elements in delivering the safety-critical functions and an overall system target.

I’m a hardware engineer what should I do?

Contact exida for books, training courses and world class experts to guide you through the complexities of functional safety and help you implement the right processes for your product and organization.

Consider buying a book and while you wait for that to arrive listen to the following webinars:

Webinar

Presenter

Title and Link

Duration

A solid introduction to functional safety and certification

Dr. William Goble

IEC 61508 Certification of Safety Equipment

56 min

For those familiar with an earlier edition of IEC 61508

Dr. William Goble

IEC 61508 (2010): What’s New and How Does it Affect Me

66 min

What you need in your development process to be compliant

Michael Medoff

Functional Safety: An IEC 61508 SIL 3 Compliant Development Process

82 min

 

I’m a software engineer what should I do?

exida has help for you. The 3rd edition of the IEC 61508 book has advice for software engineers. While you have that on order watch this webinar.

Webinar

Presenter

Title and Link

Duration

What you need to do to develop IEC 61508 compliant software

Michael Medoff

IEC 61508 Software Development Processes

64 min

 

It’s hard enough solving the robotics and providing the user interface features – are you going to make this even harder?

Look at our case studies and feedback from customers. In general, the most effective designs and most successful companies base their products around a well-designed safety architecture that gives them flexibility to provide excellent user features without compromising safety. exida specialize in helping you and demonstrating you have achieved world-class safety. We’ll help you make sure you get the right development process for your product and company.

Stopping distances and speed limits

The various clauses relating to speed and stopping distance are summarized on the chart below. CSA 336 defines two regions of interest “open space” and “confined space”. The chart below shows the two speed limits and the speed dependent stopping distance while automated.

Obstacle detection

Without referring to ANSI B56.5 Safety Standard for Driverless, Automatic Guided Industrial Vehicles and Automated Functions of Manned Industrial Vehicles CSA 336 defines two test obstacles that are very similar to the Test Pieces specified in section 8.11.1.2.1. ANSI B56.5 is available free of charge from the Industrial Truck Standards Development Foundation after free registration. Clause 20.107 of CSA specifies the requirements for detecting these test obstacles. Clause 20.108 defines requirements for dealing with edges. Requirements for stopping due to obstacles are specified in clauses 20.111, 20.112 and 20.113.

Starting, restarting and resetting

Clauses 20.101, 20.110 and 20.111 have requirements for switch off, initial start-up and restarting after stopping or contacting obstacles. These functions are all defined as safety-critical functions so subject to achieving the minimum safety integrity levels for functional safety.

 

External links (valid January 2018)

#

Reference

Link

1

CSA/ANSI C22.2 NO. 336-17 - Particular requirements for rechargeable battery-operated commercial robotic floor treatment machines with traction drives

http://shop.csa.ca/en/canada/appliances/csaansi-c222-no-336-17/invt/27043752017

2

CSA Group Store

http://shop.csa.ca/

3

ANSI/ITSDF B56.5 - 2012, Safety Standard for Driverless, Automatic Guided Industrial Vehicles and Automated Functions of Manned Industrial Vehicles EFFECTIVE 03/01/13

http://www.itsdf.org/forms/regusers/standards/12_ITSDF-B56-5-2012-rev-03-07-14.pdf [2]

 

 

 

 

 

 

 

 

[1] Prices checked January 2018

[2] Free registration required

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