Hands-on introduction to interactive

electric muscle stimulation

Abstract

In this course, participants create their own prototypes

using electrical-muscle stimulation. We provide a

ready-to-use device and toolkit consisting of electrodes,

microcontroller, and an off-the-shelve muscle

stimulator that allows for programmatically actuating

the user’s muscles directly from mobile devices.

Author Keywords

EMS; actuation; wearable; haptics; virtual reality

ACM Classification Keywords

H.5.2 [Information Interfaces and Presentation]: User

Interfaces - Interaction styles;

Introduction & Background

Haptic feedback allows leveraging sensory faculties

such as proprioception instead of using the visual

sense, which is often overloaded with traditional UIs.

However, most haptic technologies do not follow the

trend of miniaturization, i.e., mobile and wearable. In

fact, techniques such as force feedback resist

miniaturization because they require physical motors,

which do not scale down easily.

Figure 1: Our EMS mobile kit allows researchers to rapidly &

safely prototype with electrical muscle stimulation without the

need to build hardware or software.

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CHI'16 Extended Abstracts, May 07-12, 2016, San Jose, CA, USA

ACM 978-1-4503-4082-3/16/05.

http://dx.doi.org/10.1145/2851581.2856672

Pedro Lopes* and

Patrick Baudisch

Hasso Plattner Institute,

Potsdam, Germany

{pedro.lopes, patrick.baudisch}

@hpi.de * authors contributed equally

Max Pfeiffer* and

Michael Rohs

Human-Computer Interaction

Group, Leibniz University

Hannover, Germany

{max, michael}

@hci.uni-hannover.de

To overcome this challenge, researchers miniaturized

haptic devices, such as force feedback actuators, by

using electrical-muscle stimulation as to actuate the

muscles directly (Figure 1), rather than actuating

through mechanics [1]. Electrical muscle stimulation

(EMS, often clinically described as Functional Electrical

Stimulation) uses electrical impulses to elicit action on

the motor fibers/nerves, thus causing the involuntary

contraction of the user ’s muscles.

Technique has been developed in rehabilitation

medicine in the 60’s and 70’s. More recently, it has

been leveraged in HCI to provide mobile devices with

the capability of simulating both realistic forces [1] and

the sensation of impact in virtual reality [2].

Other haptic renditions made via EMS include feedback

for interacting with virtual 2D objects [8], feedback for

3D hand selection tasks [6] and manipulation of the

human locomotion system to enable actuated guidance

while walking [7].

Furthermore, systems such as the PossessedHand

demonstrated early on how EMS can assist in learning a

new skill such as playing a musical instrument or

deliver navigation notifications [9].

Lastly, researchers found use to EMS beyond emulating

haptics in mobile scenarios. The direct interface to the

user’s body has been explored in proprioceptive

interaction as an eyes-free channel for both input and

output [3]. Also, communicating with EMS via

proprioception has been used to extend the affordance

of everyday objects by actuating the user as to suggest

the correct way to manipulate these objects [4].

Course Outline for CHI 2016

This course intends to provide a hands-on experience

using EMS as a source of haptics. We believe this will

influence those who research on the fields of: haptics,

virtual & augmented reality, mobile and wearable

interfaces, even if they have no or little prior knowledge

of electrical muscle stimulation.

1. Introduction to Electrical Muscle Stimulation (EMS)

The course starts with a technical introduction to

electrical-muscle stimulation, complete with a hands-on

demonstration with the audience. The slides of the

entire course are available to the community as

recourse for further exploration1.

2. EMS-based devices in Human Computer Interaction

We then move onto a brief but dense presentation of

the last years of EMS related work within the HCI field,

focusing mainly at the CHI conference i.e., from

pioneer works such as the PossessedHand [9], up to

more recent developments such as Cruise Control [7]

or Affordance++ [4].

3. Exploring EMS through the rapid prototyping kits

Then we hand out our rapid EMS prototyping kits,

which consist of: one off-the-shelf medically compliant

muscle stimulator, a control board and a mobile phone

with bluetooth. Using this, all participants have a

chance to experience how EMS feels and learn about

the details of how to actuate different muscle groups.

4. Hands-on-prototypes: The body as an I/O device

For the last section of the course, participants will use

the kits to create simple prototypes based either on

1 Available at: http://chi16-ems.plopes.org

Figure 2: The wearable I/O

device Pose-IO is an example of

interacting via EMS [3].

Figure 3: Impacto combines EMS

and tactile to emulate impact [2].

Figure 4: Affordance++ using

EMS to allow this spray can

informs the user that shaking is

the correct usage [4].

their ideas or on existing haptic devices that are hardly

mobile (e.g., the Phantom haptic device).

Rapid Prototyping EMS Kit

We introduce a novel rapid prototyping kit2 that allows

exploring EMS without the need to build software or

hardware, which we developed for this course.

Figure 8: Participants will be provided with a kit for rapid EMS

prototyping, each kit is comprised of: (a) one mobile phone or

tablet with pre-installed apps, (b) one control board and (c) an

off-the-shelve EMS device

The toolkit (overview in Figure 8) consists of: a mobile

phone (participants can use their own) pre-installed

with two control apps, an of-the-shelve EMS device, an

arduino-based control board that modulates the EMS

signal and a set of electrodes. The control board can be

easily reprogrammed later to construct more elaborate

prototypes but it is ready to use without any

programming or configuration time.

2 Toolkit and code available at:

www.bitbucket.org/MaxPfeiffer/letyourbodymove

The kit works as follows: using the mobile application a

participant manipulates the EMS signal on the phone

interface (e.g., modulating the amplitude). The app will

send these commands over Bluetooth to the control

board (Figure 9), which will modulate the actual EMS

signal accordingly to the participant’s preferences.

Figure 9: Close up of the control board that is the core of the

rapid prototyping kit (conventional 9V battery not depicted).

Examples from our test-run workshop

In a test-run of this course, given at the IEEE World

Haptics Conference 2015 [5], participants new to EMS

successfully developed simple yet compelling

applications using our kit. Participants of our previous

workshop developed a prototype that raises awareness

about healthy drinking by making the user grasp the

healthier drink (Figure 10.a). Another example is this

a

b

c

bluetooth antenna

EMS signal [input]

modulated EMS signal

[output]

arduino microcontroller control circuit [backside]

Figure 5: Targeting 3d objects

with EMS feedback [6].

Figure 6: Experiencing virtual

hardness/softness with EMS [8].

Figure 7: Manipulating locomotion

by actuating the user’s legs [7].

simple selfie-stick, which is depicted in Figure 10.b. It

actuates the user’s arm and adjusts the frame of the

shot. It also actuates the thumb causing it to press the

button, thus taking the portrait (“selfie”) automatically.

Figure 10: Two prototypes from our test-run workshop.

Course Goals and Objectives

The course has the educational objective of exchanging

knowledge about electrical muscle stimulation in HCI.

Participants will learn the EMS basics and receive a kit

to easily explore the technology without the need of

building hardware or software. We provide participants

with a starting point to integrate EMS in their research.

Conclusions

We created a course that simplifies the exploration of

EMS, which is increasingly popular in HCI. We expect

that this brings together different researchers and

generates interesting applications around EMS.

References 1. Lopes, P. and Baudisch, P.Muscle-propelled force

feedback: bringing force feedback to mobile

devices. Proceedings of CHI'13, 2577–2580.

2. Lopes, P., Ion, A., and Baudisch, P. Impacto:

Simulating Physical Impact by Combining Tactile

Stimulation with Electrical Muscle Stimulation. In Proc. UIST’15.

3. Lopes, P., Ion, A., Mueller, W., Hoffmann, D.,

Jonell, P., and Baudisch, P. Proprioceptive Interaction. Proc. of CHI’15, 939–948.

4. Lopes, P., Jonell, P., and Baudisch,

P.Affordance++: allowing objects to communicate dynamic use. Proc. of CHI’15, 2515-2524.

5. Lopes, P., Pfeiffer, M., Rohs, M., and Baudisch, P.

Let your body move: electrical muscle stimuli as haptics. Prog. IEEE World Haptics'15.

6. Pfeiffer, M. and Stuerzlinger, W.3D virtual hand

pointing with EMS and vibration feedback. Proc. of

3DUI’15, 117–120.

7. Pfeiffer, M., Dünte, T., Schneegass, S., Alt, F., and

Rohs, M.Cruise Control for Pedestrians. Proc. of CHI’15, 2505–2514.

8. Pfeiffer, M., Schneegass, S., Alt, F., and Rohs,

M.Let Me Grab This : A Comparison of EMS and

Vibration for Haptic Feedback in Free-Hand Interaction. Augmented Human’14, 1–8.

9. Tamaki, E., Miyaki, T., and Rekimoto,

J.PossessedHand: Techniques for controlling human

hands using electrical muscles stimuli. Proc. of CHI’11, 543.