A Look at Leading Global Robotics Research:

Direct Drive Servo Motor

Robotic Finger

Edward Neff

President

SMAC Moving Coil Actuators

Man vs. Machine

Something is missing.

The Need for

Robotic Fingers and Hands

• There is a need for robotic fingers and hands that can perform the same work as human hands do.

• Why?

• Because most work done by humans is done with their hands.

Foxconn’s Disappointments

• Foxconn spent $20,000-$25,000 per robot (according to Singularity HUB) in hopes of replacing 1.5 million assembly workers. According to The Wall Street Journal, Foxconn would have to spend anywhere from $2.1 billion to over $10 billion for fully automated plants, depending on the type of robots used. Foxconn's traditional capital spending is below $3 billion.

• Since these robots were equipped with grippers they could not manipulate tools and parts in a way that could emulate human hands. According to the news stories the robots turned out to be unusable.

Underwriters Labs

• UL - a recent visit to UL (Underwriter's Labs) resulted in their asking for a Robot finger that can swipe a touch screen like a human and can feed back information about the work.

• SMAC moving coil actuators can Soft-Land on a surface and then lightly push but not in the way a finger does.

• Most important is the slide action.

• They said such a device does not exist - but is needed.

Why No Robotic Fingers?

• This inability to copy the work done by

human hands has slowed considerably the

expansion of robots in the factory.

• What has been the problem?

Forces

• The human finger can push with a force at the finger tip of around 10N. The finger is small - with joints in the 20 -30mm diameter range. The finger also can vary forces -including delicate ones.

Flexibility

• The finger is also flexible and is able to

absorb and adjust to external forces

without breaking - until it reaches the end

of motion.

Geared Motor Solution?

• A very good solution for a robot finger

would be a very powerful - small - direct

drive servo motor. A geared motor is not a

good solution since it can be easily

damaged by external forces operating on

it. Direct drive is compliant.

Developing Powerful, Small Motors

• The problem is developing a torque high enough in a small package. The “D” motor

shown here is a very good commercial direct drive motor - Swiss made - that puts

out 60mNm at 48 volts and 3 amps. The only problems are:

– The lowest torque joint - the 3rd (or PIP) - requires about 200mNm in order to put

out a resultant 10N force at the finger tip - approximately 30mm from the joint.

– The motor needs to be in the 20 - 25mm diameter range.

AB

CD

Developing Powerful, Small Motors

• A solution to this problem has been in development at

SMAC. We have progressed starting from a 35mm motor

“A” generating the same torque as the large Swiss

manufacturer of the 3rd motor from the left.

AB

CD

Developing Powerful, Small Motors

• The “C” motor shown here has a diameter

of 25mm. It runs on 48 volts using a max

current of 1.5 amps.

AB

CD

Development

• It has a torque of 140mNm and so exerts a resultant force of about 7N at the finger tip.

• The motor is the 3rd integration and is based on SMAC's moving coil design. It has a working arc of 90 degrees.

Motors

• The motor is a servo "partial" motor and is equipped with an SMAC rotary encoder

with 15.5K counts per revolution. It achieves a high torque/diameter ratio due to the

proprietary magnetic circuit design as well as the coil design. Intellectual property

rights have been addressed.

• Another - larger motor (35MM) acts as the 2nd joint (MCP FLex). It puts out a torque

of 630 mNm and thus can exert a resultant force of 7N at the tip. Both motors

move +/- 45 degrees - as the human joints do.

• The 3rd motor operates as the first joint (MCP Abd). This is the joint that moves side

to side. This motion is based on SMAC’s moving coil linear design and already meets

the required parameters.

• These motors have been integrated into a structure that allows them to operate and

cover the same movement capability as a human’s finger. The structure weighs

approximately 350 grams and is physically about 1.5 x larger than the average male

finger.

SMAC Corporation

• SMAC Corporation has had a long history of development of its MCA (Moving Coil Actuator) technology. During this time patented "Soft-Land" and Programmable force technology has been developed and are now being used around the world by major Consumer Electronic -Electronic automation, automotive, packaging, and medical companies.

• This technology can be directly applied to the finger and later the hand. So soft bumping into materials can be realized as well as programmed applied force.

Smaller and Smaller

• What happens next? Toyota's robotics group has viewed the motor and mentioned that Japanese joints are more on the order of 20MM. (I was a manager at a large Japanese components supplier to Toyota - so this comment was expected).

• That is a challenge.

• We are in the midst of the 4th and 5th FUMO (functioning model) designs which will again increase torque by 50-60% (actually, the fourth iteration just gave us another 35%). This should allow us to shrink the motors so that we can approach the actual size of even a Japanese woman's finger. (We have several of these in my family by the way). We also must drop current to the 500-750 mAmps range.

• Eventually, our targets are motors producing the correct torque (so that we can produce the required 10N at the tip) using a maximum 600 mAmps/DC current at 48 VDC.

Thumb and Controllers

• We are also busily laying out the thumb. That’s an added rotational axis.

• A multi-axis controller based on very small slave controller/amp - which is a SMAC commercial product already and a Master Controller are in early test. The MC will eventually handle up to 50 axis - there are 16 basic axis in our proposed SMAC hand.

• So- by the fall a finger/thumb combination controlled by our MC/CBC will be operating and doing work inside SMAC. Our target is to produce a "hand" with controllers - at a price of around $5000. Time will tell if this is achievable - although a good indicator is that a current single axis SMAC actuator with built in controller can be purchased for around $600 vs $3000 15 years ago.

The Future

• Fast programming technology is needed. Copy movement programming is commonplace. We are investigating other methods - such as tracking via glove and non contact tracking. Advances are being made.

• The possibility of a user-friendly prosthetic hand is real. This can be programmed to accomplish many common day actions. IP is out on this.

• And - the technology opens up the possibility for very small SCARA like robots - much better suited for small component assembly - which takes us back to the Foxconn reference in the beginning.

Conclusion

• A key hurdle holding back the application of robots in the factory has been the lack of technically capable robotic fingers and hands.

• It is now quite possible that this hurdle can be overcome. If this proves true the expansion of robots into work areas hitherto barred by the lack of robot dexterity will take place. That is a big step.

Questions?

Ed NeffPresident

SMAC Moving Coil Actuators5807 Van Allen Way

Carlsbad, Ca

USA

Phone: 760-929-7575

Email: info@smac-mca.com

www.smac-mca.com