perm filename DOC.S[1,VDS] blob sn#150175
filedate 1975-03-11 generic text, type C, neo UTF8
COMMENT ⊗ VALID 00011 PAGES
C REC PAGE DESCRIPTION
C00003 00002 MOTOR CURRENT SPECIFICATIONS FOR STANFORD ARMS
C00008 00003 MOTOR SPECIFICATIONS FOR STANFORD ARM
C00013 00004 GEAR RATIOS AND GEARING DETAILS FOR STANFORD ARM
C00015 00005 LITERATURE ON THE STANFORD ARM
C00016 00006 MOTORS
C00018 00007 ARM PROGRAMS
C00030 00009 Bearings required on arm
C00031 00010 SPECIFICATIONS FOR THE MODEL "STANFORD" ARM
C00036 00011 THE CARE AND FEEDING OF THE STANFORD ARM
MOTOR CURRENT SPECIFICATIONS FOR STANFORD ARMS
This file lists the specifications for the motors on the
mechanical arms. Arms are named by color or proposed color
and joints are numbered starting at the base and working out
to the hand..
NOTE: When it says max. current limit it means that the motor
must NEVER see a current exceeding this value even for one
Also, for sufficient maximum arm velocity, the power amps
should put out a maximum 24-28 volts d.c., bipolar.
GOLD ARM (built in 1969)
Joint #1- U9M4 motor (Photocircuits Corp.)- .84ohms, no max current limit.
design for 15-20 amps pulse (100-1000 ms.) and 6 amps cont.
Joint #2- U9M4 motor- same as Joint #1.
Joint #3- E-576-01 motor(Electrocraft)-1.55ohms, 24 amps max.current limit
design for 10-15 amps pulse and 4 amps cont.
←oint #5- same as Joint #4
Hand- NT-0739-C motor(Inland Motor Corp.)-16.7ohms, 1.55 amps max.current limit.
BLUE ARM (built in 1972)
Joint #1-U9M4 motor- see above
Joint #2-U12M4 motor- .75 ohms, no max current limit, but can design for
10-15 amps pulse(100-1000ms) and 7.5 amps continuous (5-10 secs.)
Jount #3- 3069-255 motor(Magnetic Technology)- 5 ohms,5.06 amps max. current limit.
Joint #4- BYLM-
Joint #5 BYLM-
Joint #6 Globe -
Hand- NT-0739-C See above
RED ARM (built in 1974)
Joint #1- U9M4- See Above
Joint #2- U12M4- See Above
Joint #3- 402-14(Magnedyne)- 2.6ohms, 7.5 amps max. current limit.
Joint #4- 1937D-100(Magnetic Technology)-16.7ohms, 1.4 amps. max. current limit.
Joint #5- 1937D-100- See above
Joint #6- NT-0741-C See above.
Hand NT-0741-C See Above.
MOTOR SPECIFICATIONS FOR STANFORD ARM
Feb. 22, 1975
Printed Motors Inc.- Model U9M4T ( Motor-Tachometer in single unit)
Cont Torque- 20 inoz
Max. Cont. Stall Current- 6.2 Amps
Terminal Res. .84ohms @ 25Deg. C, 1.21 ohms @ 150 deg. C.
Torque Constant- 6.1 oz-in/amp
EMF Const.- 4.5 V/1000rpm
Damping Const.- 1.2 oz-in/1000 rpm
Total Inertia- .008 oz-in sec sec.
Regulation@ const voltage- 41.6 rpm/in-oz.
Armature Inductance- <100micro-henries.
Average Friction torque- 6 oz-in.
Mecchanical Time Const.- .035 sec.
Output Gradient- 2.25v/1000rpm
Output impedance 1 ohm.
Printed Motors Inc.- Model U12M4T ( Motor-Tachometer in single unit)
Cont Torque- 66 in-oz
Max. Cont. Stall Current- 7.6 Amps
Terminal Res. .75ohms @ 25Deg. C, 1.07 ohms @ 150 deg. C.
Torque Constant-14.4 oz-in/amp
EMF Const.-10.6 V/1000rpm
Damping Const.- 4.5 oz-in/1000 rpm
Total Inertia- .033 oz-in sec sec.
Regulation@ const voltage- 6.77 rpm/in-oz.
Armature Inductance- <100micro-henries.
Average Friction torque- 6 oz-in.
Mechanical Time Const.- .023 sec.
Output Gradient- 5.30v/1000rpm
Output impedance 1 ohm.
Magnedyne Inc.- Model 402-14 (20vdc winding)
Peak Torque-300 in-oz
Max. Stall Current- 7.5 Amps
Terminal Res.2.75ohms @ 25Deg. C.
Torque Constant-40 oz-in/amp
EMF Const.-.3 V/rad/sec.
Damping Const.- 4.4 ozin/rad/sec.
Total Inertia- .029 oz-in sec sec.
Average Friction torque- 9 oz-in.
Mechanical Time Const.- .007 sec.
Electrical Time Const.- .0016 secs.
Max. continuous stalled current- 3.5 amps.
Tachometer Constants (Separate Unit) Servo-Tek, Inc.
Output Gradient- 7.0v/1000rpm
Output impedance 100 ohm.
Joints 4 and 5
Magnetic Technology Inc. Model 1937D-100-043
Peak Torque-20 in-oz
Max. Stall Current- 2.8 Amps
Terminal Res.4.3ohms @ 25Deg. C.
EMF Const.-.05 V/rad/sec.
Damping Const.- .093 ozin/rad/sec.
Total Inertia- .0015 oz-in sec sec.
Average Friction torque- 1.5oz-in.
Electrical Time Const.- .0005 secs.
Max. continuous stalled current- 1.5 amps.
Joint 6 and Hand
Inland Motors, Inc. Model NT-0741-C
Peak Torque-6.6 in-oz
Max. Stall Current- 1.55 Amps
Terminal Res.16.7 ohms @ 25Deg. C.
Torque Constant-4.5 oz-in/amp
EMF Const.-.03 V/rad/sec.
Damping Const.- .0086 ozin/rad/sec.(zero Z source)
Total Inertia- .00013 oz-in sec sec.
Average Friction torque- .35 oz-in.
Electrical Time Const.- .0004 secs.
Motor Constant- 1.10 in-oz/(watts↑.5)
Max. continuous stalled current- .7 amps.
GEAR RATIOS AND GEARING DETAILS FOR STANFORD ARM
Feb. 22, 1975
Joints 1 and 2
USM Corp. Harmonic Drives - Model 5C-100-2-BL
Reduction Ratio- 100/1
Moment of Inertia (Seen at input)-.007 oz-in sec sec
Approx. Average Spring Const.- 130,000 in-lbs/radian
Maximum Backlash- 3 minutes of arc .
Maximum output torque- 800 in-lbs.(Harmonic Drive limit)
Motor Pinion gear drives rack- 3 inches/turn.
Joints 4 and 5
USM Corp. Harmonic Drives- Model 1C-72-2
Reduction Ratio 72/1.
Moment of Inertia seen at input end-.00047 oz-in sec.sec.
Approx. Average Spring Const- 19,000 in-lbs/radian
Maximum Backlash- 5 minutes of arc.
Maximum output torque-100 in-lbs.(Drive limit)
Two stages of spur gear reduction- 80/1 overall
One stage of spur gears, and rack and pinion on output.
LITERATURE ON THE STANFORD ARM
MSPECS.S Motor current specs for the motors on all the Stanford arms.
SPECS.S General Specifications sheet on the current model Stanford arm.
ARM1.S The Care and Feeding of the Stanford Arm (Installation and early operation).
AL Report- An Automation Language.
Lou Pauls Report- Arm Trajectories, and Servo Equations- 1972-1973 stuff.
ARM.PAL [11,BES] - Shimano's PDP 11/45 arm servo routines.
REFS.DOC - Useful References on control and operation of the arms.
Globe motor details.
Typical demagnetization results
As delivered - back emf equals 9.2
Take out magnets and replace- back emf goes to 8.2
Take out magnets and press like poles together until they touch-
back emf drops to 6.2 or so.
So we see the potential torque loss due to dissassembly.
Careful disassembly gives only a 157 torque loss, but fooling
around results in up to 50% torque loss.
A good test for fully charged globe motor magnets is to see if it cogs. If it
does, then the magnets are at least 75% charged. If it doesnt, then you
have weak magnets.
Placing the poles of a globe motor between the poles of a large alnico magnet
seems to properly recharge the magnets. As an example- recharging the motor above
in this manner yeilded a back emf of 9.6. Higher than the original number- but no
doubt, when put to use, the magnets can be expected to discharge a bit in the
presence of demagentizing armature current induced fields.
As a furthur note- testing the motor with the large charging magnet between the
poles gives an emf of over 15.
TO create a macro type
THEN THE INSTRUCTIONS
TERMINATE WITH A BLANK LINE
TO EXECUTE, TYPE
TO SAVE A FILE TYPE
TO EXECUTE A FILE TYPE
Parts list for Stanford Arm
U9M4 Motor- Photocircuits Corp. Glen Cove, N.Y.
FS11-00-04-5-014 Brake. General Time, Torrington Conn.
HDC-5C-100-2-BL (2 tooth difference model) Harmonic Drive-USM Corp.,Wakefield,Mass.
030/105 Tachometer- Micro Mo Electronics, Cleveland, Ohio.
KA 040 XP3 Bearing-Prec. 3- Kaydon Bearing- Muskegon, Mich.
KB 040 XP3 Prec. 3. Bearing- Kaydon.
Potentiometer Element Material- order from New England Instrument Co.
Natick, Mass. (One sheet 3" x 18" of 100 ohms per square Resistofilm
material will make all the pot elements.)
U12M4 Motor- Photocircuits Corp.
FS11-00-04-5-014 Brake- General Time.
HDC-5C-100-2-BL- (2 tooth difference model) Harmonic Drive, USM Corp.
030/105 Tachometer- Micro Mo Electronics
KA 040 XP3 Prec. 3 Bearings 2 Required- Kaydon.
402-14 (20 vdc winding) Motor , Magnedyne Inc. Carlsbad, Ca.
FS17-00-06-5-014 Brake - General Time Co.
8103-R5K-L.10-LT Potentiometer- Beckman Helipot. Palo Alto, Ca.
477501 Bearing, New Departure
MFS3KDD Bearing- Fafnir
2112N913 N- Tachometer- HICO. , Menlo Park, Ca.
G176 Spur Gear- Boston Gear.
G583-4 Rack- Boston Gear.
34KDD Bearing- 16 reqd. -Fafnir.
1937D-100-12v. Motor- Magnetic Technology, Canoga Park, Ca.
HDC-1C-72-2 Harmonic Drive. USM Corp.
2112N913 N - Tachometer- HICO
FG2-1078-902 Brake Armature- General Time
3TKR-10-14U Bearing- Split Ball Bearing Div., MPB Bearing Corp. Lebanon, N. H.
B544DD Bearing- Fafnir
B542DD Bearing- Fafnir
P120A5-150 Gear- Winfred M. Berg Inc. 499 Ocean Av. East Rockaway, N.Y.
P120A7-52 Gear- Winfred M. Berg.
1937D-100-12v Motor- Magnetic Technology
2112N913 N Tachometer- HICO
FS08-00-04-5-014 Brake- General Time
HDC-1C-72-2 Harmonic Drive- USM Corp.
KAA10XL0 Bearing- Kaydon
MFS3KDD Bearing- Fafnir (.3750x.8750 flanged,double shields, prec. 3 or better)
MFS1KDD7 Bearing- Fafnir (.2500 x .6250 flanged, double shields-prec. 3 or better)
B541DD Bearing- Fafnir
NT-0741-C Motor- Inland Motor Corp. Radford, Va.
050/004 Tachometer- Micro-Mo Electronics
FS08-00-02-5-014 Brake - General Time
B538DD Bearing- Fafnir
B539DD Bearing - Fafnir
AVF8K20 Bearing 2 reqd.-Fafnir (or S518FC-MPB)
AVF8K16 Bearing 1 reqd.-Fafnir (or S418FC- MPB)
AVF12K20 Bearing 1 reqd.-Fafnir (or S5632FC- MPB)
P64A21-100 Gear- Winfred M. Berg.
YWS6412 Pinion Wire- Boston Gear (1 foot req'd)
P120A5-126 Gear- Berg
PS120S2-12 Gear- Berg
NT-0741-C Motor- Inland Motor Corp.
FS08-00-02-5-014 Brake- General Time
78CSB502 Potentiometer- New England Instruments
P120A10-130 Gear- Winfred M. Berg
P120S9-32 Gear- Berg
P96A5-90 Gear- Berg
PS96S4-16 s.s. pinion shaft- Berg (96dp, 16teeth)
R2-14 Rack-Berg, 1 piece reqd., 64 dp, 11 inches long.
S1-10 precision rod- Berg (.1562 dia., 24 inches long, 303 stainless steel rod)
YWS6410 Pinion Wire- 6 inches- Boston Gear (64dp, 10 teeth)
B25-4 Oilite bushing- Boston- 1 piece reqd.
S6316FCHH Bearing- MPB Corp.- 1 reqd.
S418FC- Bearing- MPB Corp. - 1 reqd.
Electrical Components Required (preliminary)
Tape Cable- Burndy or Hughes
Main Connector -Amphenol 57-40500 and 57-30500 -one each
Tape Cable Connectors- Cinch- 50-30-C10 - Four req'd.
#4 brake- #40 gauge nyclad wire- 1/4 lb. spool is enough.
Hand connector- Augat 14 pin 3m cable connector and low profile dip socket
to match- one each req'd.
3M Flex Cable
Shielded Cable- Micro Cable Corp.
Notes: Most bearing brands are interchangeable- substitutions are OK.
Gears from PIC, Sterling, Berg are interchangeable, sometimes
different bore sizes or hub styles are acceptable in case of
a particular number being out of stock.
All parts (or equivalents) listed above are supplied in the standard
proposed kit of parts for the arm. Some assemblies will be included,
where necessary. Encoder version has encoders substituting for pots
on the first three joints.
Bearings required on arm
S418FC - 2 ea
S518FC - 2 ea
S5632FC- 1 ea
S6316FCHH- 1 ea
SR6FRHH -2 ea (or Fafnir MFS3KDD .375x.875 FDD, prec. 3)
SR4FCHH - 1 ea ( or Fafnir MFS1KDD7 .250x.625 FDD, prec. 3)
3TKR 10-14U (.625x.875 x.156, prec. 1 or better)
B538DD - 1 EA
B539DD -1 EA
B541DD - 1 EA
B542DD - 1EA
B544DD - 1EA
34KDD - 16 EA
477501 - 1 EA
KA040XP0 - 3 EA
KB040XP0 - 1 EA
KAA010XL0 - 1 EA
SPECIFICATIONS FOR THE MODEL "STANFORD" ARM
LIMITS OF MOTION-EACH JOINT
#1- 300degrees total rotation
#2- 200 degrees (optional 300 degrees)
#3- 75 cm. total linear motion
#4- 330 degrees- (optional 600 degrees)
#5- 220 degrees
#6- 330 degrees- (optional 600 degrees)
Hand- 10.5 cm. maximum opening.
MAX SPEED EACH JOINT
JOINT # UNLOADED LOADED WITH 2.2 KG.- AGAINST GRAVITY
1 4 rad/sec 2 rad/sec
2 2 rad/sec 1 rad/sec
3 1.0 m/sec .5 m/sec
4 5 rad/sec 2 rad/sec
5 5 rad/sec 2 rad/sec
6 8 rad/sec 3 rad/sec
Hand 8 cm/sec 3 cm/sec
Within the defined workspace, which is a 50 centimeter
diameter hemisphere centered on a point on the same plane as the arm
base and 40 centimeters from the centerline of the base plate, the
arm will lift a rough steel block having a mass of 4.5 kg.
Maximum reach of the arm is about 1 meter. Thus the arm can
access points within a 2 meter diameter hemisphere.
ACCURACY AND PRECISION
Within the defined workspace, the arm has an accuracy of 5
millimeters and a repeatability of 2.5 mm when using potentiometer
calibration tables and 12 bit resolution a/d. With encoders on the
first three joints, the accuracy is 3 mm and the repeatability is 1.5
mm. Resolution is equal to the repeatability.
The arm runs on 120vac supply voltage.A power supply provides
+ and- 30 vdc for the servo motors and brakes.The seven d.c. motors
are controlled through linear current amplifiers which require a +-
10 volt signal range from a DAC (8 bits min.). A cable from the arm
provides the feedback signals to the computer and/or manual
controller. This cable also powers all the motors and brakes. For
the potentiometers and tachometers a reference power supply and a
minimum of a 16 channel, 12 bit a/d is required. For the encoders, a
quadrature decoder and up-down counter for each encoder is
required.The encoder electronics interface directly to the i/o buss.
TORQUE, FORCE AND DUTY CYCLE LIMITS
JOINT# MAX.CONTINUOUS TORQUE MAX.TORQUE(10%DUTY CYCLE-MAX. 10 SECS)
1 200 kg-cm 400 kg-cm
2 400 kg-cm 800 kg-cm
3 3.2 kg 7 kg
4 35 kg-cm 70 kg-cm (1 kg-cm approx. equals 1 in-lb)
5 35 kg-cm 70 kg-cm
6 10 kg-cm 20 kg-cm
Hand 2.3 kg 4.5 kg
THE CARE AND FEEDING OF THE STANFORD ARM
BY VIC SCHEINMAN
This paper explains some of the operating and maintainence
details of the Stanford Arm.
INSTALLING THE ARM
The arm must be bolted to a solid table surface or other
suitable mounting plate. The 1/2 inch screw threads on the bottom of
the base plate are for this purpose. Use them all! The wires running
down the side of the main column indicate the out of range area of
motion for joint #1, thus, these should be placed away from the
workspace. The supply cable for joint #1 can exit either thru a hole
cut in the table surface, or thru the slot cut in the base of the
arm. The two wide cables running to the other joints should be strain
relieved in such a way that they do not get in the way of the arm
when it is operating in its normal workspace. A little
experimentation will easily show where a suitable clamping point
Place the power amplifier and control box such that all the
cables from the arm will reach the box. Do not add extender cables to
the arm, as this will increase the overall resistance of the motor
drive cables and will result in slower motions and increased response
times. A typical location for the amp. box is under the table with
the cables being fed thru the table surface. Plug the amp. box into
the power supply. Again, do not attempt to extend the cable length.
The power supply plugs into 117 v.a.c. and is fused for 8 amps. An
extension cord can be used here if necessary. For semi-portable
applications, where the arm is mounted on a dolly or cart, the amp.
box, and the power supply should be mounted on the same device.
The manual control box plugs into the front of the amplifier
box, with the cable orientation colorcoded as is the case with the
cables to the arm. DO NOT PLUG THE CABLES IN BACKWARDS OR CONFUSE
THEIR ORDER! If the hand held control box is not plugged in, the arm
will not operate as the "OFF" mode is automatically selected in this
Plug the computer into the computer plug using a 50 pin 3M
ribbon connector wired to the A-D channels and DAC channels as
described later. This cable need not be plugged in if the arm is to
be used in manual mode only.
OPERATION IN MANUAL MODE
Set the manual control switch to OFF, either one will do.
Turn on the power supply, indicated by the pilot light. Place all the
brake switches in the ON or LOCK position. To grab and place the arm
somewhere, release the brakes on the proper joints, grab the arm and
move it to where you want it. Then LOCK the brakes. To move the arm
remotely, Put all the brakes in the LOCK position and then select
which joint you want to move with the joint select switch on the
manual controller. Now turn the speed and direction control knob and
the selected joint will move slowly. If anything goes wrong, release
the knob immediately and it will return to center, turning off the
servo and locking the joint. DO NOT ATTEMPT TO INCREASE THIS MAXIMUM
VELOCITY-IT IS SET LOW FOR YOUR OWN PROTECTION. If the joint stalls
under too great a load or because it has hit its own stop (joints 3-7
only) do not hold the knob on any longer than necessary, as this may
cause excessive motor heating and possible motor damage.
To operate the arm in computer mode, the arm must first be
properly interfaced with the computer. Thirteen A/D channels, 7 DAC
channels , 7 brake bit outputs and 7 enable channel outputs are the
minimum interface requirements. For more than 300 degree rotation of
joints #4 and #6 you must have two more A/D channels. A potentiometer
element power supply is also necessary. The paralleled resistance of
all the pot elements is about 200 ohms, so a 10 volt supply must be
capable of supplying at least 50 ma. To reduce precision requirements
of this supply, it helps to use an extra A/D channel to read the
supply voltage. The tachometers have bi-polar outputs, with one side
common. Should your A/D be single ended you will have to provide an
offset voltage to keep them within A/D range. You may also want to
install external tach op. amps. to set the tach gain to provide full
scale A/D signals(see table of tach maximum output signals).
The output from the DAC must be limited to less than + and -
15vdc. If you have a single ended output, an offset must be provided.
It is best to do this in an output op. amp. Some means of clamping
the output to less than 15 vdc. should be installed to insure that
the motor current limits are never exceeded, even in the event of DAC
amplifier saturation or catastrophic failure. The power amplifier
input impedance is 10k ohms. Full scale current is 15 volts input,
for each joint.
The brake drivers require a TTL driver output. A low signal
turns the brakes off. To enable the power amplifiers, FET switch
gates are provided. These, too, require TTL high level logic signals
from the computer.
To operate the arm in computer mode, the manual control box
must be plugged in and the mode selector knob set in "COMPUTER" mode.
On the present model, the only built in way of stopping the arm in
emergency is to turn the mode select knob to OFF. The computer and
manual brake switches are ORed together. Thus the manual switches
should be in LOCK position when operating the arm in computer mode.
Likewise, the computer gates should be low when operating in manual
The arm should only be operated in computer mode with a
carefully debugged program. Some sort of duty cycle protection must
be included in the program to prevent overheating of the motors. This
will normally not be a worrysome problem, but if the arm stalls up
against a surface, or else holds a large load against gravity for too
long a time, motor heating can be damaging. Prevent this by putting a
timeout in the control routine. Experience has shown that no one
trajectory should take longer than 5 seconds.
The power amplifiers are current drivers. This means that
they provide a current proportional to DAC voltage. The servo motors
are very sensitive to overcurrents. Thus it is imperative that the 15
volt dac output level never be exceeded, otherwise demagnetization of
the field magnets will result with an associated reduced torque
constant (torque/current). Because of the freeness of all the joints,
current is proportional to joint torque. Thus, the computer command
can be interpreted as a joint torque command. This should be kept in
mind when developing the servo routines.
There are no stops on several of the joints. Thus, various
protection features must be built into the software. It is also
suggested that one hand always be kept on the mode select knob when
debugging programs, to permit almost instant emergency switch off. A
separate emergency stop button connected to the I-O bus of the
computer is a valuable accessory, as the mode select switch will only
turn the power drivers off. It will not insure that the brakes are
switched to LOCK position. This can only be done in the computer on
the present version of the hand controller.
No doubt there will come a time when you will want to do
something physical to the arm. Resist this temptation mightily!! But,
if the poor arm requires maintenance, and no one in the know is
around, proceed with great caution. What follows are some general
guidelines. Sometime in the great future, a service manual of sorts
will be issued. No promises as to when!
The first point to remember is to keep your eyes open. Look
over the situation very carefully and try to diagnose the possible
problem before opening things up or removing anything. Look at the
layout drawings carefully.
The second point to remember is that everything should come
apart easily- it went together that way! If you have to use force,
you probably haven't removed all the screws, or else you are not
supposed to be taking it apart there. The motors must never be taken
apart. This means that you must not remove the armatures from within
the fields of the open motors, or open the cases of the housed
motors. To do this will result in instant demagnetization,and
resulting torque constant reduction. Don't open the arm up just to
see how it works- you don't do it on your own arms, so take the
The third point to remember is that there are lots of wires
running around the arm. Be careful not to break too many of these
when taking things apart or you'll really have a mess on your hands.
Oh yes, if you must fool with the pots, keep your cottonpicking hands
off the elements unless you have some lilly white cotton gloves on.
And do things gently, the wiper elements are fragile and bend out of
shape easily-especially during assembly or disassembly.
Fourth- you probably will have no difficulty assuring
yourself that you can maintain the arm. In case you didn't measure it
when you took it apart, the brake armature spacing is about.010-.020
inches. Also, gears run smoother if there is a little bit of backlash
(free play) rather than none. Harmonic drives can accidentally be
installed anodal. This means that the flexible inner gear which has
two less teeth than the outer ring gear has been installed with all
the difference on one side, rather than one tooth difference on each
side. You can tell that something is wrong because it will be hard to
push the wave generator (the ball bearing like thing on the motor
shaft) into place, and then the drive will be hard to back drive.
That's about it for now, I hope you have read this far before
doing anything important. Actually, if you did read all the way thru
to here-congratulations, you are one of the few people who ever
bothers to completely read anybody's instructions before plugging in
a new "toy".