Test equipment manufacturer, Automotive parts testing, Performance testing, Reliability testing, Durability testing
Rotary actuators can be adapted to form the joints of a robot, providing high levels of mechanical stiffness and torque. They have compact yet heavy-duty designs.
These kinds of actuators can be implemented to yield a torque-to-weight ratio about 10 times higher than a standard motor and Harmonic Drive configuration.
One of the advantages of rotary actuators is that they can be added to a system easily, with a simple insertion between two links. There’s no need for extra parts, such as bearings and gearheads, so joints are guaranteed to have precise and powerful movements, and links have no need for clearance. Their precision makes them ideal not only for robots, but for other industrial applications and for testing.
Position sensor options of varying accuracy (12, 17, 19 bit) can give you greater control of the servo valve, to provide the precision and special capacity needed for certain purposes. Actuators of the same size can also be designed as single-vane or double-vane types, the single-vane allowing for better range of movement and the double-vane providing more torque. This makes rotary actuators suitable for a wide variety of uses.
We are always researching different types of mounts, and we can provide actuators with different levels of power from our standard models 300 Nm (2656 in-lbs), 500 Nm (4426 in-lbs), and 1000 Nm (8853 in-lbs) at 210 bar (3045psi). Also, we have an ongoing interest in developing actuators better equipped for harsh environments, to better fit applications requiring operation underwater, in high temperatures, or in environments with high dust levels.
Our linear actuators have a basic compact design, to make it easier for the user to modify the actuator for specific purposes, when the standard models are not suitable.
Linear actuators can be used for linear movement, or, with an added link, can also provide rotary movement. One advantage of linear actuators is that they can be made smaller and narrower than rotary actuators. The standard power of these actuators is from 5 to 20 kN (1122~4489 lbf) at 210 bar (3045 psi), but they can be specially customized to have appropriate power for many different purposes.
Compared to rotary actuators, linear actuators can come in smaller sizes. However, more attention is required when using linear actuators, as they apply different levels of torque depending on the angle of the links. Pressure, force, and displacement sensors can be used with the servo valve to provide better feedback and control. Single- and double-rod types are available to accommodate control and range of motion needs.
As the adaption of hydraulics for field robots increases, small, lightweight power units are becoming essential technology. A module that is small and easy to use, yet with sufficient fluid rate, is leading the way in the realization of mobile hydraulic robots.
The general problem with HPUs is that they constantly supply more than the necessary fluid rate, which causes a loss of energy efficiency. This constant lost energy produces heat, so in order to maintain proper temperature, larger cooling systems are needed. It also causes the robot to be heavier overall, and to require more battery capacity. In order to deal with these problems, we at KNR developed a mobile power unit that supplies optimum flow to each joint at the moment the joint moves, eliminating the loss of energy and extending battery life.
HAC (Hydraulic Actuator Controller) is an actuator controller that allows the user to control the actuator easily, as if it were a motor. In fact, when you use this controller and a servo valve, it’s rather easy to control an actuator. The standard HAC supports 1-channel analog output (12bit), 7-channel analog input (16bit), 6-channel digital output, and CAN, UART, and SPI (each 1-channel). This makes the open-source controller compatible with analog-voltage displacement sensors, pressures sensors, encoders, etc., so these can be easily implemented to control the actuator speed, displacement, and torque.
The board is also open-source based to benefit the expanding interest in hydraulic robotics. As it’s compatible with Arduino, the Arduino development environment can easily be used for programming. However the HAC framework is made with several performance improvements over a basic Arduino board, including an ARM Cortex M4 processor (96 MHz). The default example code is already installed on the HAC, and its control loop update rate is 5 kHz. It also has compliance control in addition to the basic position, speed, and torque controls, making use easy and automatic for students or other users who are not robotics experts.
In addition, there are several different shield boards that can go on top of the HAC, and users can select the type of shield board that best fits their application. The HAC v2.0 shield board comes in 8 different types all supports serial and CAN interfaces basically. Except for SP, NP and LP shield boards, Others can adopt a wireless Zigbee module (option).
The HAC-B shield board is the Basic board, which supports the basic analog voltage output type position or pressure sensors.
The HAC-P shield board is made to support the basic analog voltage output position sensor, as well as the mV/V-type strain gauge based pressure sensor or load cell.
The HAC-N shield board can support an analog sin/cos-type output encoder, as well as an analog voltage output pressure sensor.
The HAC-L shield board can support an AC output LVDT or RVDT (5-6 wire) displacement sensor, as well as an analog voltage output pressure sensor.
The HAC-S shield board supports an digital output type(SSI, RS422) encoder, as well as an analog voltage output pressure sensor.
The HAC-SP board is a combination of S and P boards. It support a digital output type (SSI, RS422) encoder, as well as the mV/V-type strain gauge based pressure sensor or load cell.
The HAC-NP board is a combination of N and P boards. It support an analog sin/cos-type output encoder, as well as the mV/V-type strain gauge based pressure sensor or load cell.
The HAC-LP board is a combination of L and P boards. It support an AC output LVDT or RVDT (5-6 wire) sensor, as well as the mV/V-type strain gauge based pressure sensor or load cell.
Aside from these boards, when the user needs a shield board with other functions, we offer I/O pin mapping so the user can custom-build his or her own board for the relevant application.
(* KNR Systems can’t guarantee support for boards that users have made or customized themselves. Please see the forum for information regarding help with customization.)
At KNR, we’ve developed and optimized our own nozzle-flapper-type servo valve, specifically for use on small hydraulic robots. It operates at a bandwidth of over 60Hz (special model 90Hz), and has its own controller, which allows for control of compliance, force, and displacement. Compared to imported products, this valve is economically priced, and we provide modeling information to help improve control performance. Using this valve and other components, we are leading the way in customizing robots for specific purposes.
