Use Of Force Sensors Research Articles

Use of force sensors to detect and analyse lameness in dairy cows

Force sensors were used to detect lameness in dairy cows in two trials. In the first trial, leg weights were recorded during approximately 12,000 milkings with balances built into the...

Estimation of Elbow-Induced Wrist Force With EMG Signals Using Fast Orthogonal Search

In many studies and applications that include direct human involvement-such as human-robot interaction, control of prosthetic arms, and human factor studies-hand force is needed for monitoring or control purposes. The use of inexpensive and easily portable active electromyogram (EMG) electrodes and position sensors would be advantageous in these applications compared to the use of force sensors, which are often very expensive and require bulky frames. Multilayer perceptron artificial neural networks (MLPANN) have been used commonly in the literature to model the relationship between surface EMG signals and muscle or limb forces for different anatomies. This paper investigates the use of fast orthogonal search (FOS), a time-domain method for rapid nonlinear system identification, for elbow-induced wrist force estimation. It further compares the forces estimated using FOS with the forces estimated by MLPANN for the same human anatomy under an ensemble of operational conditions. In this paper, the EMG signal readings from upper arm muscles involved in elbow joint movement and sensed elbow angular position and velocity are utilized as inputs. A single degree-of-freedom robotic experimental testbed has been constructed and used for data collection, training and validation.

Hybrid velocity/force control for robot navigation in compliant unknown environments

We combine a “hybrid” force-/position-control scheme with a potential field approach into a novel method for collision recovery and navigation in unknown environments. It can be implemented both on manipulators and mobile robots. The use of force sensors allows us to locally sense the environment and design a dynamic control law. Multiple Lyapunov functions are used to establish asymptotic stability of the closed-loop system. The switching conditions and stability criteria are established under reasonable assumptions on the type of obstacles present in the environment. Extensive simulation results are presented to illustrate the system behavior under the designed control scheme, and verify its stability, collision recovery, and navigation properties.

Study on the Automation of Boulder Breakage by Use of Force Sensors and Image Processing

In this study, the automatic system for boulder breakage by use of force sensors and image processing was investigated. In order to carry out the full automation of the boulder breakage, the following three subtasks have to be automated: 1)detection of the boulder, 2)control of the chisel to move to the boulder and 3)carrying out the boulder breakage. In this paper, two algorithms to automate the 3) task were proposed by use of force sensors and image processing. One is the algorithm to detect the chisel sliding while pressing the boulder by the chisel. This algorithm is based on the rate of strain change measured by strain gauges which were attached beside the chisel. The other one is the algorithm to detect the boulder breakage by use of the features from the signals of strain gauges and ones from image processing. It was confirmed through the experiments that these algorithms proposed here worked well.

力覚を用いた大岩小割作業の自動化に関する基礎的研究

The automation of breaking task of huge rocks consists of 1) automatic detection of huge rocks, 2) automatic control to make the breaker tip move to the surface of the huge rocks, and 3) carrying out the breaking task. In the previous study, the image processing to detect the huge rocks and to measure the three dimensional information of huge rock position were investigated. In this study, the algorithm to judge the breaking is proposed by use of force sensors. The strain gauges were attached on the chisel of the hydraulic breaker, and signals from the strain gauges were measured. Through the experiments of rock breaking, it was found that large compressive or tensile strain were obtained at the moment of rock breaking. The utilization of the neural network was proposed in this study to construct the algorithm to judge the rock breaking. It was confirmed that this algorithm works well from the experiments.

天井走行型ロボットアームによる高齢者の自立移動支援システムの研究 （第１報） 力センサによる支援動作の制御

Since our society is rapidly aging, equipment to assist daily living of the elderly becomes important. Rehabilitation robotics or mechatronics is one solution to realize such equipment. This paper describes a prototype development of an overhead robot arm to assist walking of elderly persons. For effective use in Japanese houses, the arm is mounted on a rail. Because of the rigid construction of this arm, the user can grasp the arm and recover his/her posture to prevent falling down. Force sensors are used both to provide an easy-to-use interface and to realize safety. The sensors can detect forces both horizontally and vertically. Thresholds of forces were determined to detect the user's intention to move as well as for safety considerations. Preliminary experiments resulted that the arm could follow the standing up, walking and sitting down of the subject. It was proved that the use of force sensors was effective to control the system.

Force Control of a Single-Link Flexible Arm Using Sliding-Mode Theory

Motivated by the relation between a force acting on a flexible arm and the resultant bending deflection, this paper presents a force control technique simply via position control. The dynamic equations of a flexible arm with tip position placed on a fixed horizontal plane are modeled by an approach similar to the finite element method. Based on this model, the constraint force on the horizontal plane can be directly estimated from the motor's angle and the bending deflection, and thus the use of force sensor is no longer needed. The controller structure consists of two nested feedback loops in which the inner loop is designed for the motor's angle by a PD control algorithm and the outer loop deals with the constraint force by sliding-mode control. Experimental results are included to demonstrate the success of the developed controller.

Model Based Cutting Force Control for Milling Operations Using Position Sensors

Cutting force control is an important method to improve productivity in the milling operation. Constant load of the milling tool independent from changes in the cutting process are highly desirable. Costs and reliability prevent the use of force sensors for the industrial application. Therefore, as controlled variable the cutting force is not measured directly but is calculated by using a dynamic model based on the signals of the position sensors. The manipulated variable is the feed speed having the largest influence on the cutting force. A low order model of the milling process is estimated with force and speed signals. The control system adapts to process parameter changes. Experimental results are shown.

A new approach to the robust coordinated control of two robotic manipulators without using direct force measurements

A new approach to the robust motion and internal force control of two manipulators grasping a common object is presented. It incorporates a chatterless sliding mode control law with an internal force control scheme in which direct force feedback signals are not required. The new control law retains the simplicity and robustness of sliding mode controllers whilst the chattering problem associated with this type of controller is completely eliminated. It can be implemented without the use of force sensors thus significantly reducing the hardware costs. Simulations demonstrate the effectiveness of the new approach.