Robot Arm Kit for Romi Robot

  • Brand: Pololu Electronics
  • Product Code: 3550
  • Stock

    Warehouse Stock Status Location
    Centurion In Stock US06
    Stellenbosch New Product Arriving Soon
  • R1,098.00 (price excl. VAT)

Robot Arm Kit for Romi Robot

This Robot Arm Kit is an accessory for the Romi Chassis that allows it to manipulate small objects around it. The kit includes a micro gripper with paddles that can slide up to 32 mm apart, arm linkages for supporting the gripper, and a platform to mount everything to. The assembly is actuated by three included servos that are specially modified to provide access to their feedback potentiometers through a fourth (green) wire, which lets you detect if something is interfering with their ability to get to their commanded positions. This feedback also enables more complex closed-loop control of the arm from your main controller.


The Romi arm mounts on the rear half of the Romi chassis, just above the motors, using the included aluminum standoffs. Two standard-size servos sit at the base of the arm and control the height and tilt angle of the micro gripper while a micro servo is housed inside the gripper to actuate the paddles themselves. The larger lift and tilt servos can briefly draw up to around 1.8 A each when commanded to move abruptly, but the typical current draw should be under an amp each. The stall current of the micro gripper servo is approximately 0.8 A at 6 V. All three servos are intended to be powered from 4.8 V to 6 V (nominal) battery packs or a suitable power supply in that general range. For each servo, there is an approximately 1:1 correspondence between the servo position in milliseconds and the feedback voltage in millivolts, so for example, the feedback voltage will be around 1.5 V at the position corresponding to 1.5 ms servo pulses.


The gripper, which can be mounted to the end of the arm in either a horizontal (scoop) or vertical (crane) orientation, uses a rack and pinion design with the pinion gear mounted to the servo spline and opposing racks to keep the gripper paddles synchronized and parallel to each other throughout the range of motion.


Product Video




Shipping List


  • 1 X Micro Gripper with Position Feedback Servo
    • 1 X micro servo with position feedback
    • 1 X top micro gripper case
    • 1 X bottom micro gripper case
    • 1 X micro gripper plate
    • 1 X micro gripper pinion gear
    • 1 X micro gripper paddles with rack
  • 1 X Romi expansion platform
  • 1 X main arm
  • 1 X rear tilt arm
  • 1 X front tilt arm
  • 1 X pivot stand
  • 2 X servo mounting brackets
  • 1 X short linkage
  • 2 X pivot transfer linkages
  • 1 X tilt servo horn
  • 1 X lift servo horn
  • 1 X alternate tilt servo horn attachment
  • 1 X alternate life servo horn attachment
  • 2 X standard-sized servos with position feedback
  • 6 X 20 mm nylon spacers, 4 mm OD, 2.7 mm ID
  • 3 X 6 mm nylon spacers, 4 mm OD, 2.7 mm ID
  • 2 X 1.5″ aluminum standoffs, #2-56 thread, M-F
  • 2 X 1″ aluminum standoffs, #2-56 thread, M-F
  • 6 X 1″ #2-56 Machine screws
  • 3 X 3/8″ #2-56 machine screws
  • 4 X 1/4″ #2-56 machine screws
  • 13 X #2-56 hex nuts
  • 9 X #2 washers
  • 6 X 8 mm M3 machine screws
  • 6 X M3 hex nuts

Tags: robot, arm, kit, romi, claw

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