Robotic Dispensing Corner Quality: Approaches and Trade-offs

The landscape

Bead quality at corners and direction changes is a persistent limitation in robotic dispensing. The root cause is a mismatch between the dispensing system's material flow and the robot's TCP speed, compounded by post-corner vibration. Several approaches address this:

Approach	Strengths	Trade-offs
Speed-synchronized dispensing	Matches flow rate to TCP speed in real time	Requires compatible dispensing controller; complex setup; can't compensate for vibration
Reduced corner speed	Simple; universally available	Reduces throughput on corner-heavy geometries
Corner blending / look-ahead	OEM trajectory feature; some improvement	Limited by planner capabilities; may deviate from programmed path
Per-geometry parameter tuning	Can optimize each part independently	Labor-intensive; doesn't scale to high-mix production
Software-based motion compensation	Improves TCP speed consistency and reduces vibration at the source	Requires per-arm calibration; supported command interface required

How motion compensation works for dispensing

Software-based compensation improves the robot's motion quality so the TCP more closely follows the programmed path at more consistent speed:

Vibration compensation shapes trajectory commands to reduce excitation of the arm's flexible modes during direction changes. The TCP exhibits less post-corner oscillation, reducing bead waviness.

Accuracy compensation corrects kinematic errors and dynamic tracking effects. The TCP follows the programmed contour more faithfully, particularly on complex 3D geometries where small positional errors compound.

Key characteristics:

Addresses the motion side of the problem: Doesn't change dispensing parameters — improves the motion the dispensing system has to work with
Compatible with speed-synchronized dispensing: Cleaner motion produces a more predictable speed profile for the dispensing controller to track
No dispensing system modifications: Operates at the robot control level only
Per-arm calibration: Captures the specific vibration and accuracy characteristics of each arm
Feedforward architecture: Compensation applied before commands reach the servo loop; no production sensors required

Demonstrated performance

Greater than 80% vibration reduction — less post-corner bead waviness
Up to 5.7x TCP accuracy improvement — closer path following on complex contours
Real-time compensation at 250 Hz command rate
Compatible with MIG brazing, adhesive dispensing, sealant, conformal coating, and gasket-in-place applications
No permanent sensors or mechanical modifications
Cloud-based model identification; local runtime execution

Evaluation path

Select a dispensing application with known corner quality issues. Calibrate the arm (accelerometer-based, under one hour). Run comparative tests — same part, same dispensing parameters, with and without motion compensation. Evaluate bead width consistency at corners and post-corner waviness using your standard inspection criteria.

Current platform support: Standard Bots, UFACTORY, Trossen, and Denso.

What this means for your product

If corner quality is limiting the throughput or yield of a dispensing application, and the dispensing system itself is performing to spec, the issue is likely in the robot's motion. Software-based compensation is a lower-cost, lower-complexity alternative to upgrading the dispensing controller or adding per-geometry parameter tuning — and it addresses bead waviness (vibration) that dispensing-side solutions cannot.