Robot Safety Dr Emma Rushforth (originally by Prof Ken Young/ Margret Low) University of Warwick
Robot Safety
Dr Emma Rushforth (originally by Prof Ken Young/ Margret Low)
University of Warwick
Hazard identification & Risk Assessment
• Operational Characteristics of robots can be significantly different from other machines and equipment.– capable of high energy movements through a large
operational space.– Initiation of movement & path of robot arm different to
predict and can vary– Operating space can overlap other robots operating space or
other machines work zones– Operators can be required to work in close proximity to the
robot system.
Key Elements
• Fail safe• Reliable
– minimal down time
• Cheap• Fast implementation / modification
How it is done traditionally
• Relays• Redundancy• Physical barriers• Interlocks
Physical barriers
• Walls & interlocked gates• Barriers to material movement and maintenance• Impair view of process• Tend to cause large cells• Keep machine in as well as people out
– machining spindles– lasers
Robot controller
• Internal E-stop• Dead mans handle• Mode
– Teach• Slow• Fast
– Automatic– External
Large Cell / Multiple Access Points
• Maintenance key• All personnel
outside before system runs
Hardwired relay systems
• Inflexible• Expensive to install• Limited reusability
Modern Method
• Modular hardware• Modular software• Programmable /
configurable systems• Networks
– minimal wiring
Pilz SafetyBUS p and SafetyNET p
Light curtains
Machine access guarding Transmitter, receiver and two corner mirrors used for machine guarding
Radar detectors/Light curtains
• Can be active or inactive• Programmable for coverage• Allow increased safety during certain parts of
cycle• Require fast response to incursion
Radar/Light curtains
Variable protection zones Light curtain blanking/muting
Tool pallet/AGV variable protection zone
Programmable systems
• Function block based• Dual/Triple redundant• Programming requires direct contact with a
specialist tool & original program code for program development/alteration
• Monitoring/maintenance software tool does not permit programming
What are the Dangers
• Functionality hidden in software• Easy to program could mean easy to bypass
– software management (passwords, access, historical records)
• What is the effect of a device or network failure– not all networks are safe & some will mix safe &
unsafe devices together on a single network
Control Networks
I n f o r m a t i o n
C o n t r o l
2 4 v d c
5 0 9 - B O D
D e v i c e S a f e t y
I N F O R M A T I O N L A Y E RM E S , M I S , D a t aL o g g i n g
C O N T R O L L A Y E RH M I , P r o g r a m m i n g , A l a r m i n g ,R o b o t s
S e n s o r s , D r i v e s , R e m o t e I / OP n e u m a t i c V a l v e s
D E V I C E L A Y E R S
S A F E T Y - L i g h t C u r t a i n s , L a s e rS c a n n e r s , R e m o t e I / O - D o o rI n t e r l o c k s , E m e r g e n c y S t o p s ,
E t h e r n e t
C o n t r o l N e t
D e v i c e N e t S a f e t y b u s p
R o b o t c o n t r o l l e r s
D e v i c e N e t
Lathe
MillRobot
Light curtain
door
Key
Key
Pallet
PalletFigure 1
E-stop
Modular Safety System PNOZmultiPNOZmulti Configurator Getting Started
Robot
DoorKey interchangeexternal
KDoor switch
Key interchangeInternal
RobotEstop
LaserEstop