Grip
The Grip component was redesigned in realvirtual 6.3 with a new Simple Mode / Advanced Mode interface. If you are upgrading from 6.0, enable Advanced Mode to access the legacy properties you are familiar with.
Overview
The Grip component picks and places MUs (Movable Units) using automation signals or LogicSteps. It is essential for attaching MUs to grippers, robot end-effectors, or any moving component driven by a drive system.
Grip offers two Inspector modes:
Simple Mode (default) — streamlined interface for the most common pick-and-place scenarios
Advanced Mode — reveals all properties for sensor-based detection, cylinder-based picking, and fine-grained placement control
Simple Mode
In Simple Mode, Grip uses an OverlapSphere with the configured Grip Range to automatically find the nearest MU. No sensor is required — just position the Grip near the MU and trigger a pick.
How Picking Works
When Pick Objects changes from false to true (or Signal Pick receives a positive flank), the Grip performs an OverlapSphere at its position with the Grip Range radius. Only objects on the rvMU physics layer are detected. The nearest free MU (not already held by another Grip or Fixer) is selected.
The picked MU becomes a child of the Grip GameObject in the hierarchy. Its Rigidbody is set to kinematic — physics and gravity are turned off so the MU moves rigidly with the gripper. The MU appears in the Picked MUs list.
How Placing Works
When Pick Objects changes back to false (or Signal Pick receives a negative flank), the Grip releases all held MUs. In Simple Mode, the Auto placement cascade runs automatically:
GripTarget — Searches for a free GripTarget within 500 mm. If found, the MU snaps to the target's position/rotation and becomes its child. Physics stays off.
MU below — Raycasts downward (up to 1000 mm). If another MU is hit, the released MU is loaded onto it as a child. Physics stays off.
TransportSurface below — If the raycast hits a transport surface (conveyor), the MU is released with physics enabled — it falls onto the conveyor and is transported.
Nothing found — The MU stays frozen at its current position (kinematic, no physics).
This cascade means Simple Mode handles the most common scenarios automatically — placing on a GripTarget, stacking parts on other MUs, dropping onto conveyors, or holding in position.
In Simple Mode, the Place Mode is always Auto and the search/raycast distances use their defaults (500 mm / 1000 mm). Switch to Advanced Mode to change the placement behavior or adjust these distances.
Properties
Active (enum) Controls when this component is active in the simulation (Always, Edit Mode only, etc.).
Advanced Mode (boolean) Toggle to reveal all properties. When unchecked, only the essential Simple Mode properties are shown.
Grip Range (float) The detection radius in millimeters. Grip uses a sphere overlap to find the nearest MU within this range. Default: 10 mm.
Pick Objects (boolean) Set to true to pick the nearest MU within the Grip Range. Reacts on the rising edge only (false → true).
Place Objects (boolean) Set to true to release all currently picked MUs. In Simple Mode this is automatically toggled when Pick Objects changes.
Signal Pick (PLCOutputBool) PLC signal to control picking. A positive flank (false → true) picks, a negative flank (true → false) places.
Show Gizmo (boolean) Displays the Grip Range sphere in the Scene view for visual debugging.
Picked MUs (list, read-only) Shows all MUs currently held by this Grip.
Advanced Mode
Enable Advanced Mode to access the full set of properties. This includes all Simple Mode properties plus the sections below.
Pick Detection
Part To Grip (Sensor) Optional sensor to identify which MU to grip. When assigned, only MUs detected by this sensor are considered.
Directly Grip (boolean) If true, the MU is gripped immediately when the sensor detects it.
Pick Align With Object (GameObject) Aligns the MU pivot to this object's position and rotation before picking.
Align Rotation (boolean) Also aligns the rotation when picking (used with Pick Align With Object).
Pick Based On Sensor (Sensor) Picking starts when this additional sensor is occupied.
Pick Based On Cylinder (Drive_Cylinder) Picking starts based on the position of a cylinder drive.
Pick On Cylinder Max (boolean) If true, picking starts when the cylinder reaches maximum position. If false, at minimum position.
Place Mode
Place Mode (enum) Controls how MUs are placed when released:
Auto — Runs the placement cascade described above (GripTarget → MU below → TransportSurface → kinematic fallback). Physics is only enabled when placing on a TransportSurface; all other placements keep the MU kinematic.
Static — MU stays exactly where the gripper leaves it. Physics and gravity remain off (kinematic). The raycast cascade is skipped entirely.
Physics — MU gets gravity and physics enabled on release and falls naturally. Velocities are reset to zero first so the MU does not fly away with the gripper's motion. The raycast cascade is skipped entirely.
Grip Target Search Radius (float) Detection range in millimeters for finding nearby GripTargets during Auto placement. Default: 500 mm.
Raycast Distance (float) Distance in millimeters for the downward raycast used to detect surfaces and MUs below during Auto placement. Default: 1000 mm.
No Physics When Placed (boolean) Legacy property. If true, bypasses the Auto placement cascade and releases the MU with physics re-enabled at its current position.
Place Align With Object (GameObject) Aligns MU pivot to this object's position and rotation before releasing.
Place Load On MU (boolean) If true, the placed MU becomes a child of the MU it is placed on, creating a load-on-MU relationship.
Connect To Joint (Joint) Optional Unity Joint for physical joint-based gripping instead of hierarchy parenting.
Pick & Place Control
Pick Objects (boolean) Set to true to pick MUs.
Place Objects (boolean) Set to true to place MUs.
One Bit Control (boolean) If true, a single signal toggles between pick and place. If false, separate signals for pick and place are used.
Signal Pick (PLCOutputBool) Signal to control picking (positive flank = pick).
Signal Place (PLCOutputBool) Signal to control placing (positive flank = place). Only used when One Bit Control is false.
Events
Event MU Grip (UnityEvent) Triggered when an MU is gripped or released. Passes the MU and true for grip, false for release.
GripTarget Integration
When Place Mode is set to Auto, the Grip automatically searches for GripTarget components within the Grip Target Search Radius. If a free GripTarget is found, the MU snaps to the target's position and rotation and becomes a child of the GripTarget.
See GripTarget for details on setting up placement slots.
GripTarget vs Fixer
Both components handle MU placement, but serve different purposes:
Purpose
Passive placement slot ("parking spot")
Active station lock ("parking gate with lock")
Needs Grip?
Yes, always — only works with Grip
No — works standalone
MU arrives how?
Grip places it
Conveyor, AGV, or robot delivers it
Controlled by
Grip component logic
PLC signals (FixerFix/FixerRelease) or auto-mode
Detection
None — found by Grip's OverlapSphere
Own BoxCollider trigger or Raycast
MU parenting
MU becomes child of GripTarget
MU becomes child of Fixer (restored to previous parent on release)
Multi-MU
One MU per target
Multiple MUs via MUSFixed list
Handover blocking
No
Yes — prevents double-fixing between stations
Tag filtering
No
Yes — only fix specific part types
Use GripTarget when a Grip (robot gripper) places MUs at predefined positions. Use Fixer when MUs arrive on their own (conveyor) and need to be stopped/held by PLC control.
Demo Scenes
Open the Demo Scenes Browser and look under Object Handling for gripping demos:
DemoGrippingSimple — three demos: simple pick/place with OverlapSphere, GripTarget placement, and physics-based placement
DemoGrippingAdvanced — sensor-based detection, cylinder-based picking, and PLC signal control
See Also
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