UNIT 2016 presentation: http://www.unit-festival.com/

1. Open hardware robotics. . .
for a better future!
Norbert Braun
norbert@xrpbot.org
#unit Festival
2016-04-16
Norbert Braun Open hardware robotics

2. Outline
Why do we need open hardware robotics?
The big picture.
The XRPBot project
Our own contribution.
Norbert Braun Open hardware robotics

3. A brief history of AI
Euphoria
“In from three to eight years we will have a machine with the
general intelligence of an average human being.”
– Marvin Minsky (in Life Magazine), 1970
Will AI replace humans?
The AI winter
In 1980, most AI tasks still did not work well, much less
human level AI. . .
The AI spring
Chess world champion (1997), Go world champion (2016),
working speech recognition, . . .
Norbert Braun Open hardware robotics

4. Jobs replaced by automation
1 Changes in progress right now
e.g. factory automation, online booking/ordering, self-service, . . .
2 Changes in (commercial) development right now
e.g. fully automatic driving, natural language processing, . . .
3 Changes in research right now
e.g. advanced machine vision, grasp planning, . . .
Norbert Braun Open hardware robotics

5. Eliminating work
Will AI eliminate jobs? Yes.
Can we stop this? No.
. . . not even if we start to value hand-made goods? No,
because it is a self-amplifying process once it really starts.
Do we even want to stop it? Well. . .
Norbert Braun Open hardware robotics

6. Eliminating work
Remember: if a robot takes your job, the overall amount of goods
available remains constant, and the overall amount of free time
increases.
This is a good thing.
A problem exists not because jobs are eliminated, but because
wealth is re-distributed.
Norbert Braun Open hardware robotics

7. But we need jobs. . .
The sitation of not having to work exists today for people (born)
rich.
As Bertrand Russell points out, many in the “leisure class” are
incapable of “anything more intelligent than fox-hunting”, but it
nevertheless “contributed nearly the whole of what we call
civilization.”
Bertrand Russell, In Praise of Idleness, 1932
Norbert Braun Open hardware robotics

8. The future: Star Trek vs. Elysium
The technology in Star Trek
(TNG) is sufficiently advanced
that they could send drones and
avoid all danger, but they choose
to not do so because they want
an exciting life.
At the end of Elysium, all
problems are basically solved by
telling the computer to care
about all humans, not just the
elite.
Both movies are examples where post-scarsity society is possible,
but in one case it is allowed to exist and in the other it is
intentionally not.
Norbert Braun Open hardware robotics

9. How to get to Star Trek?
Distribute wealth by political means: unconditional basic
income.
Problem: power remains in few hands.
Distribute wealth by capatalistic means: eliminate barriers to
entry. Open source/open hardware.
Both have strengths and weaknesses. Probably, a combination is
needed.
Norbert Braun Open hardware robotics

10. Democratization of technology
Competition ensures that profits are minimal, and benefits
from automation are thus distributed
Like Linux/Open Source and the Internet
We need an open hardware
robotics movement!
Norbert Braun Open hardware robotics

11. XRP: Goals
The eXperimental Robot Project
Life-size humanoid robot
Focus on legs (walking), arms and hands will come (much)
later
Fully free (open source, open hardware), transparent
development process
Goal: state-of-the-art software, hardware optimized for
cost/manufacturability
Norbert Braun Open hardware robotics

12. Why humanoids?
Wheels ideal in dedicated environment (streets), otherwise
fairly limited
Human environments made for humans, wheels are really
limiting (wheelchair!)
Service robots
Disaster recovery
The real reason: they are cool. . .
Norbert Braun Open hardware robotics

13. Other projects
Progress on humanoids appears to be heating up
Big company players (Boston Dynamics, Schaft Google)
extremely secretive
University projects more, but still not fully, open
Exisiting robots cost ≥ 100 ke (our goal: few ke)
Physics-based character animation is a hot topic at
SIGGRAPH (but usually not on physical hardware)
Norbert Braun Open hardware robotics

14. Why is walking a hard problem?
Industrial Robot vs. Biped
TU Munich
Norbert Braun Open hardware robotics

15. Why is walking a hard problem?
Industrial Robot vs. Biped
TU Munich
Norbert Braun Open hardware robotics

16. Industrial Robot vs. Biped
Main difference
Industrial Robot: Base bolted to ground
Biped: stance leg only kept in place by friction
Industrial Robot: one actuator per degree of freedom
“Any” trajectory can be followed
Biped: reaction forces on stance foot not directly controllable
Intrinsic dynamics matter
No longer “any trajectory possible”
Norbert Braun Open hardware robotics

17. Simulation: Introduction
Simulate robot using simplified physics models
Goal: develop controllers
Goal: evaluate actuation requirements
Goal: inform design choices
Use dedicated dynamics toolkit plus external engine (Open
Dynamics Engine: ODE, http://www.ode.org/) for
verification
Use a rigid body model
Norbert Braun Open hardware robotics

18. Robot model
x
z
y
0
0
Side view
y
z
x
0
0
Front view
LR
Pelvis/torso
Hip (HZ, HY, HX)
Thigh
Knee (KY)
Shank
Ankle (AY, AX)
Foot
Norbert Braun Open hardware robotics

19. Demo #1: Walking on flat ground
Demo time!
Leg length: 1.0m (all demos)
Step length: 0.6m
Step time: 0.7s
Speed: 0.85 m/s, 3 km/h
Norbert Braun Open hardware robotics

20. Demo #2: Unmodelled uneven terrain
Demo time!
Step length: 0.6m
Step time: 0.7s
Speed: 0.85 m/s, 3 km/h
(as before)
Norbert Braun Open hardware robotics

21. Demo #3: Modelled uneven terrain
Demo time!
Step length: 0.4m
Step time: 0.7s
Speed: 0.57 m/s, 2 km/h
Norbert Braun Open hardware robotics

22. Demo #4: Stairs
Demo time!
0.2m
0.3m
Variable step length: 0.3m - 0.5m
Step time: 0.7s
Norbert Braun Open hardware robotics

23. Control strategy: summary
Control strategy based on contact force management
+ Reasonable performance
o Foot positions fixed in advance
+ Can be used by higher-level controller, e.g. for climbing stairs
− Limits options for push recovery (cannot take sidesteps)
− Leg length constraints not taken into account
Norbert Braun Open hardware robotics

24. . . . to reality
New problems:
Rigid body parameters not exactly known
In fact, not even rigid bodies any longer
Motors have finite max. torque, finite bandwidth
Gears have backlash
External disturbances
. . .
Can be investigated in simulation to some extent, but experiments
required for deeper insight!
Norbert Braun Open hardware robotics

25. Actuation requirements
Ballpark estimates:
Peak joint torque: ∼ 100 Nm
Peak velocity: ∼ 20 rad/s
Peak power: ∼ 250W (per DoF)
Note: can make robot smaller to reduce torque requirements
Current design goal: ∼ 120cm, ∼ 30kg (subject to change)
R/C servos have ∼ 100 Ncm = 1 Nm!
How about R/C brushless motor?
Norbert Braun Open hardware robotics

26. Gear Requirements
Brushless motor easily delivers power, but as low torque at high
speed.
Ballpark estimates:
Peak joint torque in order of 100 Nm
Motor torque ∼ 2 Nm
Needed reduction ∼1:50
Options left:
Gearing: Harmonic Drives, Planetary Gears
Linear actuators: Ball screws, Planetary Roller Screws
Hydraulics
All of these suck to some extent!
Norbert Braun Open hardware robotics

27. Norbert Braun Open hardware robotics

28. Current status/Outlook
Preparatory phase: simulation, study exisiting designs
Workshop (Dingfabrik Cologne) mostly set up: milling
machine (Deckel FP2), small CNC lathe, electronics
Biggest challenge: actuation concept
Ready to start construction after gear question is solved
Norbert Braun Open hardware robotics

29. Thank you!
http://xrpbot.org
I, for one, welcome our robot overlords.
Norbert Braun Open hardware robotics