Research findings and design recommendations from the multi partner Low Carbon Vehicle Technology Project. The project investigated the use of the driver interfaces by early adopters of Low Carbon Vehicles, and their influence on user experience. Trends in the design of relevant HMI were reviewed, together with analysis of primary data from electric and hybrid vehicle trials in the UK, and secondary data from users‟ blogs and field trials in Europe and North America.

1. Human Machine Interfaces in Low Carbon Vehicles
Findings from the CABLED trial
Low Carbon Vehicle Technology Project: Workstream 13
November 24th 2011
Tom Wellings
Lead Engineer
WMG, University of Warwick

2. Workstream members
WMG, The University of
Warwick (project lead)
Tom Wellings
Prof. Mark Williams
Dr. Alex Attridge
Jaguar Land Rover Research
Duncan Robertson
Lee Skrypchuk
Dr. Carl Pickering
Coventry University School of
Art and Design
Dr. Jackie Binnersley
Prof. Andree Woodcock
Prof. Mike Tovey
Tata Motors European
Technology Centre
Tawhid Khan

3. What are Human Machine Interfaces?
•
Any point at which a user interacts with the vehicle
•
HMI enables control of the car itself, and of in-car technologies
•
HMI also feeds back information about the vehicle's state to the driver

4. Why is HMI important?
•
HMI design is a strategic differentiator for OEMs
•
LCVs will introduce new technologies and issues for
the user
•
Safety implications
•
The experience of interacting with the HMI needs to
be positive to increase adoption of LCVs
•
Consumers' desire for advanced telematics and
connected services
•
Customers are spending longer periods of time
inside their cars

5. User centred approach
Task 13.1
Agree research objectives based on partners’ requirements
Task 13.2
Identify sources of existing LCV user data specific to HMI.
Analyse data, and prioritise main design issues that need addressing
Task 13.3
Select participants and trial methods for capturing user feedback
from LCV users
Task 13.4
Collect primary data from LCV users
Task 13.5
Analyse primary data from LCV users. Identify key issues and
possible solutions
Task 13.6
Build HMI driving simulator, and trial prototype HMI solutions

6. Aim and objectives
Aim: To identify the key HMI concerns and appropriate solutions specific to
users of Low Carbon Vehicles
•
Conduct dedicated user-centred research to investigate owners’ experience of driving LCVs.
The emphasis will be on HMI needs and driver behaviour.
•
Build a driving simulator to conduct user trials on concept HMI. The focus will be on evaluating
the user experience and acceptance of new technologies

7. Task 13.2 – Findings: User issues
Priority
Category
Issue
Range Anxiety Range anxiety due to fear
of running out of charge
Design problems raised from the research findings
What HMI changes/new features can OEMs implement in order to reduce range
anxiety?
Range anxiety reducing
with experience
Problems with charging
What is the optimal HMI design for vehicle charging feedback? Location on the
vehicle? What charging states? Feedback time-out?
Frequency of charging
What is the best way that the OEM can remind (but not nag) the user to charge the
vehicle?
Location of charging point
What is the best way for the OEM to inform the driver of the location of charging
points in the near vicinity?
Unreliable information
about range and charging
What are the 'HMI rules' that any range or charging information should abide by in
order to promote confidence in the data?
Lack of engine noise
Charging
What HMI changes/new features can OEMs introduce to 'speed-up' this reduction in
range anxiety?
What is the most appropriate method of compensating for the lack of engine noise as
a form of driver feedback?
Optimising range
In what way can drivers be encouraged to safely adapt their driving style or chosen
routes, such that efficiency is improved?
One-foot driving
What are the implications (if any) of 'one-foot driving' on the design and engineering
of the accelerator and braking pedals?
Priority
Feedback
Adapting
behaviour

8. Task 13.2 - Deliverables
HMI 2.0 report

9. Data collection instruments for
CABLED trial
• Questionnaires, Interview and focus group - based on the themes identified in Task 13.2
Theme
Research Questions
Is the occurrence of range anxiety related to familiarity with the vehicle?
In what way is battery charge information conveyed to the driver?
Range anxiety and lack of Does the battery charge information meet the drivers expectation and needs
confidence in feedback
In what way is range information conveyed to the driver?
Do they trust this information?
Does the range information meet the drivers expectation and needs
How long does it take customers to fully charge their vehicle, and do they think this is satisfactory?
The charging process
Did customers forget to charge the vehicle at any time?
How often do customers use public charging stations, and does this change over time?
How can the act of plugging in and setting the vehicle to charge be improved for the customer?
What are the benefits of having an 'economy mode'?
User adaptation to eco- Note: economy mode is a feature which turns off the vehicle's systems/features in order to maximise the vehicle's
range
driving
How can driver behaviour (i.e. things the driver has control over) influence the economy of low carbon vehicles?
Other user-issues
concerning vehicle
feedback
Are drivers aware of the vehicle's state, i.e. on and ready to be driven, or turned off.
When customers are not in their vehicle, what information about it do they want to know?
How useful is the information provided to the driver when using the vehicle

10. Main research topics
User Issue to be investigated
1
Description of data classified in this
theme
Design problems from Task 1 research
findings
Range anxiety and lack of
confidence in estimated range,
and state of charge feedback.
User issues where feedback of
estimated range, or state of charge
information to the driver was
deemed unpredictable.
What are the 'HMI rules' that any
range or charging information should
abide by in order to promote
confidence in the data?
E.g. due to outside temperature,
chosen route, use of ancillary
systems, inaccurate calculation
2
Problems with the process of
Issues related to vehicles failing to
charging, frequency of charging, charge, low charge warnings,
and reminding users to recharge. diagnosis of faults, location of the
charging socket, and problems with
plugging-in
What is the optimal design of HMI for
vehicle charging feedback?
What's the best way that the OEM
can remind the user to charge the
vehicle?

11. Trial vehicles - Mitsubishi iMiEV
Battery state of charge (SOC) dial with 16 segments
Power in/out gauge with eco-zone
Estimated range display - calculated from
consumption of electricity for the last 15
miles driven + air conditioning usage
A low energy warning
indicator flashes when
only 2 segments
remain visible
Power down warning lamp - will
light up when the battery energy
level becomes zero

12. Trial vehicles - Smart fortwo Electric
Drive
The primary HMI associated with
the powertrain are two analogue
dials on top of the instrument
panel.
No specific feedback for estimated
range
Power in/out gauge - the needle moves anticlockwise
when energy is being recovered through regenerative
braking, and clockwise when energy is being used
(+10kW to -30kW)
Battery state of charge (SOC)
From 0-20% the dial is coloured red/orange
LCD message display shows the proportion of the motor's
maximum power (in KW) that is capable of being delivered

13. Trial vehicles - Tata Vista EV
The primary HMI associated with the
powertrain are two analogue dials within
the instrument cluster.
No specific feedback for estimated
range
Battery state of charge (SOC)
From 0-10% the dial is coloured red,
from 10-20% the dial is coloured
orange.
Power in/out gauge - the needle moves
anticlockwise (past the 12 o'clock position) when
energy is being recovered through regenerative
braking, and clockwise when energy is being used

14. Methodology
• Data was collected using questionnaires and interviews.
> In collaboration with Oxford Brookes University
• Data collected at different points in time – pre-use, 1 week experience, 3+ months experience
Mitsubishi
i-MiEV
0
Smart
fortwo
Tata vista
Total
6
18
24
Interview
4
10
6
20
Post-trial questionnaire
17
9
15
41
Pre-trial questionnaire
Limitations in the data:
•
Delays in vehicle availability for participants led to some missing data
•
Some participants had completed trials before HMI questions could be incorporated

15. Findings: Range anxiety and lack of
confidence in feedback
Not all the vehicles provided an estimated range - most drivers wanted this
• Trust in estimated range was split (61% trusted it, 32% didn’t trust it, 7% no opinion)
“The remaining range indicator is not accurate. It might read 60 and after half a mile it
drops to 55 - this means you can never have confidence in it.”
‘Unreliable’ range and state of charge feedback actually due to:
• Extreme outside temperature (cited by 77% of respondents), Driving style, Using heaters and
air conditioning.
“Range predicted does not properly account for driving style or use of heat/ fan/ lights. It
tends to overestimate range left.
Recommendations:
• Investigate different ways to present information about range and state of charge to drivers
• EV drivers need dynamic information on factors that influence available range
• Range display should take account of external temperature, use of climate system, and route.

16. Findings: Range anxiety and lack of
confidence in feedback
Guidance for maximising economy
• 78% of drivers said it was important to understand how their driving behaviour can maximise
economy
Where would be an effective location for displaying guidance on maximising economy?
Location of
information
In-car
Participants
who agreed
Participants
Participants who
who disagreed did not express
an opinion
Total
100%
0%
0%
100%
On the web
54%
17%
29%
100%
Driver`s manual
56%
12%
32%
100%
Smart phone
37%
29%
34%
100%
Sample size = 41
Recommendations:
•
Provide guidance/training on how to drive economically – in-car at the minimum
•
Investigate different ways to present information about range and state of charge to drivers

17. Findings: Range anxiety and lack of
confidence in feedback
Eco-feedback
• Eco-feedback interfaces which aim to encourage more efficient driving behaviour are likely to
become more commonplace
• Fuel savings in the order of 6% to 15% can be achieved
• OEMs that implement these systems well, can differentiate their brand, and provide real
benefits to users
• Combining goal-setting with feedback has proved to be a particularly effective strategy for
encouraging behaviour change
• These principles have been most successfully applied in the Ford SmartGauge interface as
found in the Fusion hybrid, and the LCD cluster in the Chevrolet Volt
> Drivers finding the SmartGauge rewarding, and useful for maximising fuel economy.

18. Findings: Range anxiety and lack of
confidence in feedback
Remote access to vehicle information
How useful it would be to have access to certain types of information when away from the
vehicle?
Type of information
Participants who
thought it would
be useful
Participants who Participants who
did not think it
did not express
would be useful
an opinion
Total
Range
85%
10%
5%
100%
Charging progress e.g. charging finished
75%
20%
5%
100%
Electricity cost of last charge
65%
35%
0%
100%
MPG data
60%
15%
25%
100%
Vehicle location
20%
80%
0%
100%
Sample size = 20
"I think there should be a little key fob or something that you carry with you […] that
shows you how charged up your car is […] just to give you some sort of security and
comfort that you’re not going to get back to your car and find that it’s not charged."
Recommendations
•
•
Provide remote access to information about range, and charging progress
Remind users to recharge

19. Findings: Problems with the process of
charging
The physical charging process
• Frustration when car did not charge as expected; e.g. hardware malfunction
• Users wanted feedback indicating when charging was taking place, and the majority of drivers
wanted the information to be available remotely.
• Users get frustrated if it is not easy to connect the plug to the charging socket (particularly in
the dark)
"I just think it’s quite tricky to line up.…… it could be illuminated in some way. Either on
the connector itself or within the fuel cap itself could be some kind of light“
• Externally visible lights showing charging progress draw attention and are seen as a security
risk
Recommendations:
• Provide remote access to information on SoC and charging progress

20. Findings: Problems with the process of
charging
Reminding users to recharge
• 27% of participants had forgotten to recharge their vehicle on at least one occasion
• Implications are greater than for IC engine cars
"It would be great if [the car] could tell you at night. 'Hey you forgot to plug me in'.”
Recommendations:
• Ensure vehicle reminds users to recharge – but without nagging
• Consider notifications in addition to in-car warning

21. Findings: Problems with the process of
charging
Using public charging stations:
• Problems included: charging stopping for no reason, non-EV vehicles being parked in the
charging bays, and people unplugging the vehicle.
“The first time I plugged in at a public charging point, some bloke or lads thought ‘oh get
in’ and unplugged it”
• Not knowing where public charging stations were
Recommendations:
• Incorporate measures to prevent unauthorised unplugging when charging
• Provide drivers with in-car information about the location of charging points and their
availability
• Provide remote access to information on charging progress

22. HMI simulator
•
Industry leading Octal SCANeR Studio software – realistic 3D environment
•
Jaguar XJ buck providing premium vehicle cockpit environment
•
Reconfigurable instrument cluster for testing driver information concepts
•
Force feedback steering system

23. Future work - Range display user-trial
• User Issue: Drivers say they cannot trust the vehicle
feedback for range and SoC
“As I began my journey, the charge meter went
down much faster than I expected it to”
“Although we had only travelled 27 miles the
dial was showing we had used 34 miles.”
• Research question: Which variables governing the way
the available range value is displayed are most
important to instil confidence for EV drivers?

24. Benchmarking
Chevrolet Volt REEV
Nissan Leaf EV
HMI evaluation questionnaire
> Gather users’ opinions and feedback on
the HMI in each vehicle after a drive
•
Several drivers commented on the complexity
and duplication of information across the
instrument cluster and central display in both
vehicles

25. Benchmarking
Eco-feedback and range display
Chevrolet Volt eco-feedback - ball
moves under braking and acceleration
More sensitive to braking severity
Movie describing unexpected behaviour of
range display in Chevrolet Volt.
Should range value increase while you are
driving?

26. Workstream 13 publications
Task 13.1
Task 13.2
Task 13.5
Benchmarking
Agree research objectives based on partners’ requirements
Report: WS 13 objectives + tasks_v3_TS gateway
Identify sources of existing LCV user data specific to HMI.
Prioritise main design issues that need addressing
Reports:
• HMI 1.0 - LCV at Geneva motor show
• HMI 2.1 - HMI in LCVs Market analysis and User issues_Public
• HMI 3.0 - OEM research priorities 20110209
Analyse primary data from LCV users. Identify key issues possible solutions
Report: HMI 4.1 - Task2 CABLED report 20111109
Conferences:
• A survey of HMI issues in electric vehicles (Transport Design and UX 2011)
• HMI and the User Experience in Low Carbon Vehicles (Interact2011)
• Supporting Sustainability In The Design Of Electric Vehicle Interfaces:
Lessons learnt from early adopters (Ergonomics & Human Factors 2012)
Build HMI driving simulator, and trial prototype HMI solutions
Report: JRR-2011-0788 Chevrolet Volt (2011) Benchmark report Issue01

27. OEM application of WS13 knowledge
Knowledge gathered in Workstream 13 has been used to:
• Develop the standards for HMI of Low Carbon Vehicles (JLR) :> ‘A’ surface – covering charging task, charging port location
> Touchscreen content - covering charging management & navigation.
> Instrument cluster content – covering new LCV elements, warning messages, content in
different vehicle power modes, start-up sequence, menu content, EV mode.
> Switchgear – covering hybrid modes.
• Develop HMI concepts for EV driver information display (esp. estimated range calculation and
display) [TMETC].

28. Questions?
Email: tom@emotivesystems.co.uk
A.Attridge@warwick.ac.uk