Gripper Options & Specs

MSG gripper stroke variants

General specs

Power supply: 24V
Idle power: 0.5W
Operating temperature: -5 to 65 °C
Communication interface: CAN bus
CAN baud rate: 1 Mbit/s
Material: PETG plastic
Stroke: 3 options: 55 mm, 105 mm, and 155 mm

Gripper stroke

MSG gripper with a 150 mm rail

The image shows an MSG gripper with a 105 mm stroke using a 150 mm rail. Other options are:

With a 100 mm rail, stroke is 55 mm
With a 200 mm rail, stroke is 155 mm

Gripper force options

Another modular option is support for different stepper sizes. A larger stepper provides more torque but increases gripper weight. Options are:

21.5mm stepper
40mm stepper
60mm stepper

Grasps

The gripper can perform 2 types of grasps:

External grasp – Used to hold objects by applying pressure from the outside.
Internal grasp - Allows you to grasp hollow objects by applying pressure from the inside

Pinout and connection

MSG gripper pinout and connector diagram

The gripper is powered and controlled with a single cable that carries CAN bus communication and a 24V power supply.

Voltages

To power the gripper, use 24V. You can send commands to the gripper using a 5V CAN bus.

3D model

Link to the STEP model

MSG gripper 3D model render

Torque curves

Coming soon!

As shown in the plot, the relationship between current and applied force is linear. The unit of current is ampere [A], and the unit of force is newton [N].

Torque curve

This plot only applies to grippers bought from Source Robotics that use BLDC motors with a fine-tuned Kt of 0.325. If you build your own gripper, this value might be different.

CAN bus termination

CAN termination switch on the MSG gripper

You can adjust this by flipping the switch to "ON" to enable 120 ohm CAN bus termination and to "1" to disable it.

STEPFOC driver config

Config

If you bought the gripper, it comes preconfigured and calibrated.

If you are building the gripper, send the following commands over serial to place the BLDC controller in gripper mode and enable the thermistor:

#Gripper 1
#Term 1
#Kiiq 0.3
#Kpiq 3
#Save
#Clear
#Gripcal

Gripper linear speed calculation

Gripper minimum and maximum speed are commanded and returned in 0-255 format. In STEPFOC firmware, these values are mapped to ticks/s: 255 = 60000 ticks/s while 0 = 500 ticks/s. Use this formula to calculate linear speed of the gripper jaws:

r = 0.0083 m, C is the commanded speed from 0–255

\[ \text{ticks_per_s} = 500 + \left(\frac{60000 - 500}{255}\right) \times C \]

\[ \omega = \frac{\text{ticks_per_s}}{2^{14}} \times 2\pi \]

\[ v = \omega \times r \]

Gripper force calculation

You can find your Kt value for your specific motor using the UART command #Kt.

Iq units

Units of Iq are in mA. Convert to A before calculations.

\[ T = K_t \times I_q \]

\[ F = \frac{T}{r} \]