Gripper Type Taxonomy
The gripper is where the robot meets the world. Choosing the wrong gripper is the single most common cause of low grasp success rates. There are six major gripper categories, each suited to different object geometries, surface properties, and throughput requirements.
| Type | Examples | Force / Stroke | Weight | Price | Best For |
|---|---|---|---|---|---|
| Parallel Jaw (2-finger) | Robotiq 2F-85, OnRobot RG2, Schunk EGP | 20-235 N / 20-85 mm | 0.3-1.0 kg | $1,500-$5,000 | Rigid objects, boxes, cylinders, machine tending |
| Vacuum / Suction | OnRobot VGC10, Schmalz, Piab | 15-150 N holding / N/A | 0.2-0.8 kg | $500-$3,000 | Flat surfaces, boxes, packaging, sheet material |
| Magnetic | Schunk EMH, OnRobot MG10 | 3-15 kg holding / N/A | 0.5-2.0 kg | $1,000-$3,000 | Ferrous metal parts, sheet metal, stamped components |
| Soft / Compliant | Soft Robotics mGrip, RightHand RightPick | 5-30 N / adapts to shape | 0.2-0.5 kg | $2,000-$8,000 | Delicate/irregular items, food, produce, e-commerce |
| 3-Finger Adaptive | Robotiq 3-Finger, Barrett BH8-282 | 15-60 N / 0-155 mm | 1.0-2.3 kg | $5,000-$15,000 | Mixed objects, research, high-variety bin picking |
| Dexterous Hand | Allegro Hand, LEAP Hand, Orca Hand | 2-10 N per finger / 12-24 DOF | 0.5-4.0 kg | $2,000-$120,000 | In-hand manipulation, tool use, dexterity research |
Task-to-Gripper Mapping
| Task | Recommended Gripper | Why |
|---|---|---|
| Pick-and-place (rigid boxes) | Vacuum or Parallel Jaw | Vacuum for top-down picks on flat surfaces; parallel jaw for side grasps |
| Bin picking (mixed objects) | Soft gripper or 3-finger adaptive | Adapts to unknown shapes; tolerates pose uncertainty |
| CNC machine tending | Parallel jaw (long stroke) | Rigid grasp on machined parts; IP67 rating for coolant |
| Food handling | Soft gripper (food-grade silicone) | Gentle grip, FDA-compliant materials, washable |
| Sheet metal handling | Magnetic or vacuum | Magnetic for ferrous; vacuum with flat cups for non-ferrous |
| Research data collection | Parallel jaw (Robotiq 2F-85) | Standard in research; excellent ROS2 support; reproducible results |
| Dexterous manipulation research | Dexterous hand | Required for in-hand rotation, tool use, and fine manipulation |
ROS2 Integration
Most modern grippers provide ROS2 drivers or can be controlled via simple serial/Modbus commands wrapped in a ROS2 node. Key integration patterns:
- Robotiq 2F-85/140: Official
robotiq_driverROS2 package. Publishes gripper state, accepts position/force commands. Works with MoveIt2 grasp pipeline. - OnRobot grippers:
onrobot_driverpackage via TCP/IP. Simple open/close with force feedback. - Vacuum grippers: Typically controlled via digital I/O on the robot controller. ROS2 integration through the robot driver's I/O interface (e.g.,
ur_robot_driverGPIO service). - Custom/3D-printed grippers: Control via servo motor (Dynamixel or hobby servo). Use
dynamixel_sdkROS2 package or direct PWM via GPIO.
For OpenArm 101, we provide pre-tested gripper integration for Robotiq 2F-85 and a custom 3D-printed parallel jaw gripper included in the base package.
Selection Checklist
- What is the maximum object weight? (determines minimum grip force: F = m * g * safety_factor, typically safety_factor = 3-5)
- What is the object size range? (determines required stroke/opening width)
- What surface properties? (smooth/rough, porous/sealed, wet/dry -- affects vacuum and friction grip)
- How many different objects? (1-3: specialized gripper; 10+: adaptive/soft gripper)
- What is the cycle time requirement? (vacuum grippers are fastest: 0.1s grasp; dexterous hands are slowest: 1-5s)
- IP rating needed? (IP40 for clean rooms; IP67 for wet/dusty environments)
- Weight budget at end-effector? (subtract gripper weight from arm payload for usable capacity)
- Communication protocol? (must be compatible with your robot controller)
OpenArm Compatible Grippers
The OpenArm 101 has a standard ISO 9409-1-50 flange and supports these tested gripper configurations:
- Included: Custom 3D-printed parallel jaw (30 mm stroke, servo-driven, 100g weight, 200g grip force)
- Recommended upgrade: Robotiq 2F-85 ($2,500) -- 85 mm stroke, 235 N force, position feedback
- For dexterous research: Orca Hand with Paxini tactile sensors
- For suction tasks: OnRobot VGC10 ($1,800) with vacuum cups