WR BEAR User manual

BEARTM Operation and SDK Manual
Westwood Robotics R
Corporation
v 0.2.6
c
2020 Westwood Robotics
All Rights Reserved
1

Contents
1 Introduction 3
1.1 About This Manual ..................................... 3
1.2 Warnings .......................................... 3
1.3 Know Your BEAR ...................................... 4
2 Using BEAR 10
2.1 Power & Signal ....................................... 10
2.2 Communication ....................................... 14
2.2.1 Control Table .................................... 14
2.2.2 Detailed Description ................................ 16
2.2.3 Error Code ..................................... 17
2.3 Operating Modes ...................................... 18
2.4 PID Tunning ......................................... 20
3 SDK 23
3.1 PyBEAR ........................................... 23
3.2 LabBEAR .......................................... 30
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1 Introduction
1.1 About This Manual
•Type of a data is enclosed with “<>”. For example, <list>is a data type in Python.
•BEAR is also referred to as BEAR motors, BEAR actuators or BEAR modules.
•CAUTION labels contain advises and instructions that, if not properly followed, can possibly
lead to damage or malfunction on your BEARs.
This is an example of CAUTION label.
CAUTION labels contain advises and instructions that, if not properly followed, can
possibly lead to damage or malfunction on your BEARs.
CAUTION
•WARNING labels contain restrictions and instructions that, if not properly followed, will defi-
nitely lead to severe damage on your BEARs, and can result in dangerous situations.
This is an example of WARNING label.
WARNING labels contain restrictions and instructions that, if not properly followed,
will definitely lead to severe damage on your BEARs, and can result in dangerous
situations.
WARNING
1.2 Warnings
To avoid structural deformation, please NEVER clamp your BEAR from the side.
WARNING
To avoid leakage, please do not loosen or tighten the screws on the cooling channel cap or
disassemble the cooling channel cap. The gasket must be replaced once disassembled.
WARNING
3

In Direct Force Mode, the output speed of BEAR is not limited by the limit velocity max
setting.
WARNING
Pay extra attention when changing mode while BEAR is enabled. BEAR will remain enabled
and execute the corresponding goal xxx setting in the new mode immediately.
WARNING
Do not save configurations when the motor is enabled. The motor may not respond when it
is writing flash memory.
WARNING
1.3 Know Your BEAR
a) Koala BEARTM V2 (KB02)
Koala BEAR V2(KB02) is a small actuator designed for highly dynamic applications with rel-
atively low loads, such as all kinds of small mobile robots, robot hands or robot manipulators.
The mechanical and electrical as well as the thermal management features are introduced
as following, with the help of figure 1.
Weight Speed Constant KVTorque Constant KTSupply Voltage
250 g 22 RPM/V 0.35Nm/A 9 ∼33.6V (3 ∼8S)
Stall Torque 15sec Stall Torque 15sec(LC) Stall Torque 1.5sec Reflected Inertia
3.5 Nm 4.2 Nm 14 Nm 1.82 ×10−3kg/m2
Table 1: Koala BEAR V2 Specification1
•Mechanical Features The dimensions and locations of mounting features are anno-
tated as in figure 1. There are six M3 screw holes and six 3mm pin holes on the output
shaft for locating and connecting the payload. The eight M2.5 screw holes, four 2.5mm
pin holes located on the front side as well as the four M3 screw holes and four 2mm
pin holes on three sides can all be used to locate and mount KB02 to its application.
Besides, there are also four M3 screw holes on the back that are axisymmetric about
the output shaft, and these four M3 screw holes can also be used as mounting points
or to mount additional bearings under certain application.
1Stall Torque is the maximum torque BEAR can deliver for more than 10 seconds under given thermal condition; LC
stands for Liquid Cooled.
4

Figure 1: Koala BEAR V2 Specs
When high axial load is expected at the application joint, additional axial support
is required instead of directly use Koala BEAR for the axial support on the joint.
CAUTION
Please refer to Table. 1for overall mechanical and performance properties of KB02.
•Electrical Features KB02 has one XT30 power port, and two Molex PicoBlade 53047
6Pin signal ports. The two signal ports make it convenient to connect multiple BEAR
modules in serial. Power supply voltage for KB02 ranges from 9V to 32V.
When driving the load dynamically, a non-negligible back EMF will be generated
by BEAR upon backdrive or impacts. In such applications, it is highly recom-
mended to use Li-Po batteries as power supply or add a big capacitor to the
power supply circuit as a buffer to protect the power supply.
CAUTION
•Liquid Cooling The headers of the liquid cooling channel on KB02 are push-to-connect
headers for 4mm OD tubes. The applied coolant pressure in the cooling channel can
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be up to 1MPa. It is recommended to use DI water mixed with appropriate amount of
biological inhibitors as coolant. It is not recommended to add other additives or dyes
into the coolant.
. To prevent damage to the circuit from coolant leakage, please apply/replace
PTFE sealant tape on the thread of the cooling channel headers before attaching
them onto your BEAR and check for leakage carefully.
CAUTION
Refrain from using Copper (II) Sulphate (CuSO4) additive – common trade name
“Nuke Cu” or “Biocide Cu” – due to its tendency to react with metals usually found
in the liquid cooling loop, especially radiators (Zn, Cu, Sn) as well as BEAR (Al)
thus promoting corrosion. Using CuSO4also accelerates visually discouraging
copper tarnishing phenomena.
CAUTION
In the case of regularly liquid cooled applications, please check for leakage in the
liquid cooling loop at least weekly.
CAUTION
To avoid leakage, please do not loosen or tighten the screws on the cooling chan-
nel cap or disassemble the cooling channel cap. The gasket must be replaced
once disassembled.
WARNING
b) Panda BEARTM V2 (PB02)
With the right balance of torque, weight, and form factor, Panda BEAR V2(PB02) is our
most versatile unit. Its excellent dynamic performance and payload capability makes it well
suited for diverse applications ranging from legged mobile robots to service and entertain-
ment robots. The mechanical and electrical as well as the thermal management features are
introduced as following, with the help of figure 2.
•Mechanical Features The dimensions and locations of mounting features are anno-
tated as in figure 2. There are eight M3 screw holes and eight 3mm pin holes on the
output shaft for locating and connecting the payload. The eight M3 screw holes and
3mm pin holes located on the front side as well as the six M3 screw holes and six 2mm
pin holes on each of the three sides can all be used to locate and mount PB02 to its
application. Besides, there are also eight M3 screw holes on the back that are axisym-
metric about the output shaft, and these eight M3 screw holes can also be used as
mounting points or to mount additional bearings under certain application.
6

Figure 2: Panda BEAR V2 Specs
When high axial load is expected at the application joint, additional axial support
is required instead of directly use Panda BEAR for the axial support on the joint.
CAUTION
Please refer to Table. 2for overall mechanical and performance properties of PB02.
Weight Speed Constant KVTorque Constant KTSupply Voltage
685 g 10.7 RPM/V 0.67Nm/A 9 ∼50.4V (3 ∼12S)
Stall Torque 15sec Stall Torque 15sec(LC) Stall Torque 1.5sec Reflected Inertia
13.4 Nm 16.8 Nm 33.5 Nm 7.44 ×10−3kg/m2
Table 2: Panda BEAR V2 Overall Mechanical Properties2
•Electrical Features PB02 has one XT60 power port, and two Molex PicoBlade 53047
6Pin signal ports. Pry open the back cap to access the signal ports, as instructed in
figure 3. The two signal ports make it convenient to connect multiple BEAR modules in
serial. Power supply voltage for PB02 ranges from 9V to 48V.
2Stall Torque is the maximum torque BEAR can deliver for more than 10 seconds under given thermal condition; LC
stands for Liquid Cooled.
7

Figure 3: Panda BEAR Signal Ports
When driving the load dynamically, a non-negligible back EMF will be generated
by BEAR upon backdrive or impacts. In such applications, it is highly recom-
mended to use Li-Po batteries as power supply or add a big capacitor to the
power supply circuit as a buffer to protect the power supply.
CAUTION
•Liquid Cooling The headers of the liquid cooling channel on PB02 are push-to-connect
headers for 4mm OD tubes. The applied coolant pressure in the cooling channel can
be up to 1MPa, but it is recommended to regulate your coolant pressure under 0.7MPa
if your system’s coolant is pressurized at all time. It is recommended to use DI water
mixed with appropriate amount of biological inhibitors as coolant. It is not recommended
to add other additives or dyes into the coolant.
. To prevent damage to the circuit from coolant leakage, please apply/replace
PTFE sealant tape on the thread of the cooling channel headers before attaching
them onto your BEAR and check for leakage carefully.
CAUTION
Refrain from using Copper (II) Sulphate (CuSO4) additive – common trade name
“Nuke Cu” or “Biocide Cu” – due to its tendency to react with metals usually found
in the liquid cooling loop, especially radiators (Zn, Cu, Sn) as well as BEAR (Al)
thus promoting corrosion. Using CuSO4also accelerates visually discouraging
copper tarnishing phenomena.
CAUTION
8

In the case of regularly liquid cooled applications, please check for leakage in the
liquid cooling loop at least weekly.
CAUTION
To avoid leakage, please do not loosen or tighten the screws on the front cap or
disassemble the front cap. The gasket inside must be replaced once disassem-
bled.
WARNING
9

2 Using BEAR
2.1 Power & Signal
a) Power
The power port on KB02 is a male XT30 connector and the power port on PB02 is a male
XT60 connector. The power port polarity follows the regular convention of XT30 and XT60
connectors: the pole near flat side is positive and the pole near the rounded/chamfered side
is ground, as shown in fig. 4
Figure 4: BEAR power connector and polarity
Be cautious and never reverse power polarity.
WARNING
Power supply voltage for different BEARs are as listed in Table. 3. Connect BEARs getting
same voltage in parallel when using multiple BEARs.
To avoid fire hazard, please estimate nominal current consumption on each BEAR
when chaining multiple BEAR in parallel and select power cable with appropriate AWG,
especially higher current consumption is expected.
WARNING
Product Name Koala BEAR Panda BEAR
Supply Voltage V 9 ˜ 32 9˜ 48
Connector XT30 XT60
Table 3: BEAR Power Supply Specs
b) Indicator
Each BEAR has an LED indicator on the back side. There are three(3) LEDs with different
colors on the indicator that indicates the status of the actuator: Grean,Blue and Red.
The Grean light comes on once BEAR is powered and initialization is complete; The Blue
LED lights up as soon as the torque output is enabled, and turns off once disabled; The Red
light indicates an existing Error.
c) USB2BEAR
It is recommended to use Westwood Robotics USB2BEARTM high speed RS485 USB dangle
to connect BEARs to your computer.
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