Test & measurement
improVing how Data accelerates autonomous
Vehicle technology
including a first-of-its-kind advanced driver- assistance systems (ADAS) record offering. The announcement was made during NI Connect, the test and measurement company’s premiere digital event for engineers. The new ADAS record offering combines
N In this case, both vertical-axis and horizontal-
axis accelerometers are used to determine the angular acceleration due to gravity. By constantly monitoring the tilt angle and angular velocity of the pendulum, a PD (proportional-derivative) control system can be used to drive the wheels forwards or backwards to maintain balance. Adopting a similar approach in their own
control system, Ishikawa’s students needed to design and integrate what was effectively a three-part solution, comprising tilt-angle sensing, control logic and motor drive circuitry. When designing PCBs for this control application, small size and low weight is crucial for integration within the handlebars. PCB architectures have been optimised to ensure that all the required functionality is delivered in the smallest package size.
Solution
The PCB control board sits at the top of the pendulum, inside the handlebars, and carries all the electronic circuitry required, including a solid-state gyroscope, microcontroller, DC motor drive and power management components. In the wheeled platform, at the bottom, there
are two axles: a horizontal axle linking the wheels and a vertical axle driven by a compact DC motor. Simple bevel gearing at the intersection between the axles enables the
motor to drive the wheels in either direction. For effective control, the system must maintain
orientation within a small range of angles that are nearly vertical. If the vehicle tilts by more than 30 degrees in either direction, stability might be lost. To maintain balance, the wheels must be driven continuously with carefully calculated acceleration and speed. To achieve the required level of motion
control performance, the students needed a high-resolution position encoder to enable monitoring and regulation of the motor output. It also had to be small and light enough to be accommodated within the vehicle's slim vertical structure. After much consideration, the solution came
in the shape of the RM08 rotary magnetic encoder from RLS, a Renishaw associate company. This non-contact, frictionless rotary magnetic encoder weighs just 2 g, including cabling, and features an aluminium sensor housing measuring 8 mm in diameter with a thickness of only 3 mm. The students designed a narrow nylon collar, to
act as a mechanical linkage between the motor shaft and the magnetic actuator of the RM08 encoder, which added less than 0.5 g to the assembly. The RM08 encoder produces a 12-bit resolution output (4,096 steps per revolution), is suitable for high-speed operation up to 30,000 rpm and delivers an accuracy of ±0.3 º.
ReSultS
By using the RM08 high-speed rotary magnetic encoder to measure angular rotation at 12-bit resolution, the Tokyo Denki University students were able to design a motion control scheme for a two-wheeled robotic vehicle capable of self-balancing and staying upright. The RM08 encoder is IP68-rated and
designed for integration into a wide range of high-reliability, high-volume OEM applications. Importantly, the rotary magnetic encoder also
addressed the vehicle’s demanding physical design constraints. Being a highly compact and lightweight component, it helped the students overcome both space and load-carrying limitations. The success of this project has given the
students the confidence to explore other advanced robotics projects.
Renishaw Instrumentation Monthly September 2021
www.renishaw.com
NI’s high performance in-vehicle data logging systems with Seagate’s data transfer and edge storage services, enabling original equipment manufacturers (OEMs) and suppliers to efficiently leverage data to ensure the safety and reliability of the next generation of autonomous vehicles. The latest autonomous vehicles require
more real road data than ever before, making efficient data storage all the more important. With this innovative ADAS record offering, OEMs and suppliers can modernise their data storage strategy from self-managed to storage as a service (StaaS), leading to reduced costs and efficient storage. The offering combines NI’s Data Record System AD in-vehicle data logger for ADAS and autonomous vehicles with Seagate’s Lyve Mobile edge data transfer services.
I and Seagate Technology Holdings are to collaborate to enhance data storage and transfer services,
“Seagate’s Lyve Mobile helps avoid lengthy lead
times and added cost for edge data storage hardware by moving from a CapEx to an OpEx model,” says Chad Chesney, NI senior vice president and general manager of the Transportation Business Unit. “As we announced at NI Connect, this collaboration with Seagate is a key component of how NI will accelerate the product life cycle for ADAS components and autonomous vehicles. Our open, partner-driven approach connects experts across an entire workflow to improve quality, speed and outcomes on the path to Vision Zero.” Seagate’s Lyve Mobile accelerates access to
the data collected by autonomous vehicles for analysis and algorithm optimisation. Lyve Mobile Array can be directly mounted to the vehicle’s trunk and can store all the data in real time. After the data logging ride has been completed, it can be transported to the closest edge data centre and can directly transfer the data for immediate use.
NI
www.ni.com 31
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