Hardware Specifications

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Baxter is a humanoid, anthropomorphic robot sporting two seven degree-of-freedom arms and state-of-the-art sensing technologies, including force, position, and torque sensing and control at every joint, cameras in support of computer vision applications, integrated user input and output elements such as a head-mounted display, buttons, knobs and more.

The Baxter Robot was designed for continuous operation and can run 24/7 for expended periods of time without the risk of damaging the hardware of the robot. It is recommended that the robot be connected to an uninterruptible power when running continuously in order to prevent hard drive corruption in the event of a power outage that can cause an improper shutdown of the robot. If the hard drive of the robot becomes corrupt due to an improper shut down, a fresh install (or factory reset on robots running v1.2 or later) will be required.

Baxter Arm Specifications

Joint Names

Baxter's joint names are mentioned a number of times in this documentation. A labeled diagram can be found below (S=Shoulder, E=Elbow, W=Wrist)

Baxter Joint Names.png

Link Lengths

Link lengths for Baxter's joints are measured in mm, from the center of one joint to the center of the next. They can be found in the image below.

Baxter Link Lengths.png

Range of Motion - Bend Joints

The range of motion for each bend joint is presented below. The table shows the measurements in degrees and radians

Baxter RangeMotion 1.png

Joint Range Table (Bend Joints)
Joint (Degrees) Min limit Max limit Range (Radians) Min limit Max limit Range
S1 -123 +60 183 -2.147 +1.047 3.194
E1 -2.864 +150 153 -0.05 +2.618 2.67
W1 -90 +120 210 -1.5707 +2.094 3.6647

Range of Motion - Twist Joints

The range of motion for each twist joint is presented below. The table shows the measurements in degrees and radians.

Baxter RangeMotion 2.png

Joint Range Table (Twist Joints)
Joint (Degrees) Min limit Max limit Range (Radians) Min limit Max limit Range
S0 -97.494 +97.494 194.998 -1.7016 +1.7016 3.4033
E0 -174.987 +174.987 349.979 -3.0541 +3.0541 6.1083
W0 -175.25 +175.25 350.5 -3.059 +3.059 6.117
W2 -175.25 +175.25 350.5 -3.059 +3.059 6.117

Maximum Joint Speeds

Maximum Joint Speeds (rad/sec)
Joint Maximum Speed
S0 2.0
S1 2.0
E0 2.0
E1 2.0
W0 4.0
W1 4.0
W2 4.0

Joint Flexure Stiffness

Flexure Stiffness (K)
Joint Stiffness
Small Flexures (W0, W1, W2) 3.4deg @ 15Nm (~250Nm/rad)
Large Flexures (S0, S1, E0, E1) 3.4deg @ 50Nm (~843Nm/rad)

S1 Spring Specifications

S1 Spring Specs
Description Spec
Spring Type JIS standard die spring: ASF 35 X 200
Free Length 200 mm
Stiffness (K) 9.6 N/mm
Operating length 101 mm - 154 mm

Joint Sensor Resolution

  • The resolution for the joint sensors is 14 bits (over 360 degrees); so 360/(2^14) = 0.021972656 degrees per tick resolution.
  • All of the joints have a sinusoidal non-linearity, giving a typical accuracy on the order of +/-0.10 degrees, worst case +/-0.25 degrees accuracy when approaching joint limits. In addition, there may be an absolute zero-offset of up to +/-0.10 degree when the arm is not calibrated properly. Be sure to tare and calibrate the arms if you're trying to minimize accuracy errors in the joint sensors.

Note: The performance of the joint controllers is a separate matter; ultimately, the accuracy of the controller is only limited by the accuracy of the sensors. In a case where joint position controllers are included, we use a threshold to determine when the joint states are "close enough" to the commanded joint angles to call it acceptable. In the baxter_interface for the RSDK, we use a default threshold of: JOINT_ANGLE_TOLERANCE = 0.00872664626 radians (0.5 degrees), which is set in settings.py and used by the limb interface and the joint_position examples. If you want to improve the accuracy, you can write your own controller to adjust the setpoint and to overcome any steady-state error in the internal low-level controllers. Even when the joint controller is slightly off the target position, it always knows exactly how far off it is, via the joint position sensors.

Peak Torque

The peak torque specification refers to the maximum amount of torque that can be applied to each joint.

Peak Torque Per Joint
Joint Peak Torque
S0,S1,E0,E1 50Nm
W0,W1,W2 15Nm

Other Hardware Specifications

Camera Specifications

Description Spec
Max Resolution 1280 x 800 pixels
Effective Resolution 640 x 400 pixels
Frame Rate 30 frames per second
Focal Length 1.2mm

On Board CPU

Description Spec
Processor 3rd Gen Intel Core i7-3770 Processor (8MB, 3.4GHz) w/HD4000 Graphics
Memory 4GB, NON-ECC, 1600MHZ DDR3
Hard Drive 128GB Solid State Drive

Component Weights

Description Spec
Total weight (with pedestal) 298 lbs / 135.2 kg
One Arm 47 lbs / 21.3 kg
Torso 70 lbs / 31.8 kg
Pedestal 134 lbs / 60.8 kg

Electrical Power

Description Spec
Battery Operation DC-to-120V AC Inverter (Note: the Baxter robot has an internal PC, which cannot be powered directly off of 24V DC)
Interface Standard 120VAC power. Robot power bus and internal PC both have “universal” power supplies and support  90 - 264V AC (47 - 63Hz)
Max Consumption 6A at 120V AC, 720W max per unit
Electrical Efficiency 87% to 92%
Power Supply Uses medical-grade DC switching power supply for robot power bus
Tolerance to sags Sags tolerated to 90V. Sustained interruption will require manual power-up
Voltage Flicker Holdup time 20mS
Voltage Unbalance Single phase operation only

Miscellaneous Specifications

Description Spec
Screen Resolution 1024 x 600 pixels
Positional Accuracy +/- 5 mm
Max Payload (including end-effector) 5 lb / 2.2 kg
Gripping Force (max) 35N or 8 lbs
Infrared Sensor Range 1.5 – 15 in / 4 – 40 cm