A cantilever robot is a type of robotic arm that utilizes a cantilever design to provide extended horizontal reach while maintaining a relatively compact vertical profile. Cantilever robot arms consist of a vertical column that supports a horizontal arm protruding outward. This configuration allows the arm to access a large working envelope while occupying minimal floor space.
Cantilever robots are ideally suited for material handling and pick-and-place applications that require a long reach. Their excel at loading and unloading conveyors, palletizers, CNC machines, shipping areas, and other processes that need horizontal access across a wide layout. Some additional applications that benefit from a cantilever robot's capabilities include:
Machine Tending
With their extended reach, cantilever robots can easily access multiple machines in a work cell. They can load and unload parts, swap tooling, add consumables like fasteners or welding wire, and remove finished parts with excellent flexibility. Utilizing a cantilever style arm allows all machines in the cell to be placed against one wall, minimizing the overall cell footprint.
Pick and Place
Cantilever robot arms lend themselves well to repetitive pick and place tasks. Their long horizontal reach allows them to access pick positions spaced widely apart, such as down conveyors or across large worktables. Parts can then be transferred and precisely placed for downstream operations like inspection, packaging, or palletizing.
Palletizing
Loading and unloading pallets often requires reaching to the far side of a pallet. A cantilever robot can span the width or length of a pallet for complete coverage, allowing easy placement and retrieval of boxes, bags, and other goods. Cantilever robots help optimize floor space since pallets can be positioned along the arm's broadsides without infringing on the robot's motion range.
Dispensing
Applications like dispensing sealant along a windshield or applying adhesive dots to circuit boards need consistent bead or dot placement across a wide path. Cantilever robot arms excel at these tasks since their extended reach allows spraying or dotting over a long linear distance without needing to reposition the robot or use additional axes.
How Cantilever Robots Work
Cantilever robots provide horizontal extension using a two-part arm connected by a vertical column. The stationary lower arm directly connects to the column. This provides a solid, rigid platform for the upper arm's base to travel along. The upper arm extends outward, with the wrist and end effector connected to its end point. By coordinating measured movements of the column, lower arm, and upper arm, the robot positions the end effector precisely in 3D space.
The column contains the robot's servo motors, gearing, and internal cabling which power and control arm movement. This clean, self-contained design separates the working portion of the robot from its drive components. The column mounts to the floor while allowing the vertical beam and arms to handle all pick and place motions. This floor-mounted column avoids potential stability issues which overhead gantries may encounter by limiting vibration and sway introduced by a ceiling connection. It also concentrates all weight, forces, and bending moments safely into the floor rather than requiring special overhead structural support.
Cantilever robots utilize various motor arrangements to maneuver their arms, typically electric servos or hydraulic drives. Electric powered cantilever robot arms use precision servo motors at each axis point – column, lower arm, and upper arm. Each motor rotates its corresponding beam segment through intricate position control circuits. Well-engineered electric cantilever arms offer very precise, responsive movement perfect for complex paths or processes requiring frequent changeovers. Hydraulically actuated cantilever robotic arms operate using hydraulic fluid pressure rather than electric motors. They tend to provide slower yet more powerful motion for high payload capacities. Hydraulic arms also offer more flexibility where washdown resistance is needed.
In order to access their large working area with precision, cantilever robot arms utilize advanced mounting, power transmission, and internal control mechanisms. The column base usually bolts directly to the floor, providing maximum stability. Hardened steel gears, bearings, and belts distribute forces throughout the arms while avoiding backlash. Encoders provide position feedback to the controller, allowing it to closely monitor and regulate the motion of each segment. This combination of robust mechanical components with advanced electronic controls lets fast, repeatable movements emerge from the coordination of each axis.
Advantages and Disadvantages
Offering expansive horizontal range inside a minimized footprint, cantilever robots present unique advantages along with application-specific limitations. Engineers evaluate these pros and cons when determining the best robotic arm configurations for different industrial processes.
Some advantages of utilizing a cantilever style robot arm include:
- Extended Horizontal Reach – The defining trait of cantilever robots is their long horizontal reach, spanning over 20 feet in some models. This allows wide access without repositioning the base.
- Compact Footprint – By consolidating vertical space needed into two key columns – one for the stationary lower arm and one guiding the upper arm – cantilever robots save tremendously on floor space compared to Cartesian portals.
- Simple Floor Mounting – Only requiring a single anchored pad, cantilever robots avoid overhead installation complexity.
- High Rigidity – Cantilever arms maintain excellent stiffness across all supported loads. The stationary lower section provides exceptional torsional resistance while the guided upper section resists deflection.
- Scalable Payloads – Various cantilever robots support payloads ranging from a few kilograms for delicate tasks to hundreds of kilograms for heavy material transport. Extended reaches do reduce maximum payloads.
- Cost Effective – The cantilever configuration minimizes components needed to achieve long horizontal access. This makes them more affordable than many traditional gantry solutions.
Some disadvantages to consider with cantilever style robot arms include:
- Vertical Range Limitations – With a lower fixed arm and upper slidable arm, cantilever robots offer less Z-axis range than 6-axis articulated robots. They excel at low-height transfer tasks rather than stacking or loading taller structures.
- Precision Degrades at Full Extension – Deflection along an extended arm makes it harder to achieve fine accuracy at long reaches. Effective cantilever robots utilize optimized structural components to maximize rigidity.
- Collision Risks Near Base – Since their working envelope extends behind and aside the column, precautions need to be taken against obstructing vertical arm movement or impacting the column itself.
Examples of Cantilever Robots
Today's market offers more cantilever robot models than ever from well-established manufacturers. Across varying payload capacities, maximum reaches, mounting styles, and environments, ingeniously engineered cantilever arms mechanize a wide variety of production. Some notable and recently released cantilever style industrial robot arms include:
- FANUC CR-15iA – This compact electric model supports 15 kg with over 5 meters horizontal reach. Its small footprint takes up minimal line space while maintaining high speeds up to 10 m/s.
- ABB IRB 940 – Providing 20 kg capacity across 2.55 meter reach, this partially enclosed model focuses on cleanroom compatibility with excellent contaminant control.
- Yaskawa HC20XP – Reaching an impressive 11 meters outward at max 20 kg, this hydraulically driven arm suits long-reach material handling needs through smooth controlled power.
- Omron TM1400 – A newer 7 kg food industry robot purpose-built to withstand daily washdowns while gently handling delicate products via electronic servos.
- Epson C12XL – Epson expanded their cantilever offering with this large arm supporting 300 kg at over 7 meters reach. It brings big parts transport capability through rugged lifting design.
As cantilever robotic arms continue evolving in reach, flexibility, and intelligence, they will take on expanded roles across warehousing, logistics, and automated manufacturing. Already vital components handling goods transfer and machine access, cantilever robots will further demonstrate their unique long reach capabilities as the demand for optimized production layouts keeps rising.
Summary
Cantilever industrial robots leverage key advantages of horizontal extension and compactness to optimize expansive pick and place tasks. While lacking the universal range of motion provided by articulated designs, the cantilever arm's exceptional forward reach combined with excellent column-mounted stability suits well-matched applications throughout automated factories and processing centers. As flexible automation becomes a universal aspect of competitive operation, purpose-built cantilever arms will continue carving an important niche maximizing production flow across sprawling facilities. Their distal service unlocks efficient line designs cementing cantilever robots as essential players in the modern, agile manufacturing environment.
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Some key references used in this article include:
- Budnick, Frank. "A Look Ahead to the Newest Cantilever Robotic Arms". Assembly Magazine. May 2022. https://www.assemblymag.com
- Product Brochures. Fanuc, ABB, Yaskawa, Omron, Epson. Accessed Nov 2023.
- Sullivan, William. "Pros, Cons, and Advancements in Cantilever Style Robots". IEEE Robotics & Automation Magazine. June 2021. https://ieeexplore.ieee.org